,transcrib]'s notes3 ,9 ! *emical equations1 sup]scripts are indicat$ ) a & subscripts are indicat$ ) a 4 ,! affect$ item is enclos$ 9 curly brackets 4 ,examples are ,h = hydrog5 ion & ,h#b,o = wat]4 ,s9ce ! und]score is already be+ us$ 9 ?is project1 italics are designat$ by an exclamation po9t be=e & aft] ! italiciz$ ^w or phrase4 ,,an ,,introductory ,,c\rse ,,( ,,quantitative ,,*emical ,,analysis ,,) ,,explanatory ,,notes ,,by ,,h5ry ,p4 ,,talbot ,,pr(essor ,,( ,,inorganic ,,*emi/ry ,,at ,,! ,,massa*usetts ,,in/itute ,,( ,,te*nology ,,six? ,,edition1 ,,completely ,,rewritt5 ,,preface ,?is ,introductory ,c\rse ( ,quantitative ,analysis has be5 prep>$ to meet ! ne$s ( /ud5ts :o are j ent]+ ^u ! subject1 aft] a c\rse ( qualitative analysis4 ,x is prim>ily int5d$ to enable ! /ud5t to "w successfully & intellig5tly )\t ! necessity = a l>g] measure ( p]sonal assi/ance & sup]vision ?an c reasonably be giv5 to ea* memb] ( a l>ge class4 ,to ?is end ! directions are giv5 9 su* detail t !re is v little opportunity = ! /ud5t to g a/ray2 b ! manual is n1 ! au?or believes1 on ?is acc\nt less adapt$ = use ) small classes1 :]e ! in/ructor1 by great] p]sonal influ5ce1 c /imulate indep5d5t ?\ght on ! "p ( ! pupil4 ,! me?od ( pres5tation ( ! subject is t sugge/$ by ,pr(essor ,a4,a4 ,noyes' excell5t manual ( ,qualitative ,analysis4 ,= ea* analysis ! proc$ure is giv5 9 consid]able detail1 & ?is is accompani$ by explanatory notes1 :i* are believ$ to be suffici5tly exp&$ to enable ! /ud5t to und]/& fully ! und]ly+ reason = ea* /ep prescrib$4 ,! use ( ! book %\ld1 nev]!less1 be supplem5t$ by classroom in/ruction1 ma9ly ( ! "* ( recitations1 & ! /ud5t %\ld be taught to consult l>g] works4 ,! g5]al directions are int5d$ to emphasize ^? matt]s ^u :i* ! beg9n] 9 quantitative analysis mu/ be/[ special c>e1 & to (f] helpful sugge/ions4 ,! /ud5t c h>dly be expect$ to appreciate ! =ce ( all ! /atem5ts conta9$ 9 ^! directions1 or1 inde$1 to reta9 !m all 9 ! memory aft] a s+le read+2 b ! in/ructor1 by frequ5t ref]5ce to special p>agraphs1 z suitable occasion pres5ts itself1 c soon r5d] !m famili> to ! /ud5t4 ,! analyses select$ = practice are ^? compris$ 9 ! fir/ c\rse ( quantitative analysis at ! ,massa*usetts ,in/itute ( ,te*nology1 & h be5 *os51 aft] an exp]i5ce ( ye>s1 z af=d+ ! be/ prep>ation = m advanc$ "w1 & z satisfactory types ( gravimetric & volumetric me?ods4 ,f ! latt] po9t ( view1 !y also seem to furni% ! be/ insight into quantitative analysis = ^? /ud5ts :o c devote b a limit$ "t to ! subject1 & :o may nev] ext5d _! /udy beyond ! field cov]$ by ?is manual4 ,! au?or has _h opportunity to te/ ! effici5cy ( ! c\rse = use ) su* /ud5ts1 & has f\nd ! results satisfactory4 ,9 place ( ! usual cu/om ( select+ simple salts z mat]ial = prelim9>y practice1 x has be5 f\nd advantage\s to sub/itute1 9 mo/ in/ances1 approximately pure samples ( appropriate m9]als or indu/rial products4 ,! difficulties are n greatly enhanc$1 :ile ! /ud5t ga9s 9 practical exp]i5ce4 ,! analytical proc$ures describ$ 9 ! foll[+ pages h be5 select$ *iefly ) ref]5ce to _! usefulness 9 tea*+ ! subject1 & ) ! purpose ( af=d+ z wide a v>iety ( processes z is practicable )9 an introductory c\rse ( ?is "*4 ,! scope ( ! manual precludes any ext5d$ attempt to indicate alt]native proc$ures1 except ?r\gh g5]al ref]5ces to l>g] works on analytical *emi/ry4 ,! au?or is indebt$ to ! /&>d works = _m sugge/ions = :i* x is impracticable to make specific ackn[l$gm5t2 no consid]able cr$it is claim$ by him = orig9ality ( proc$ure4 ,= _m ye>s1 z a matt] ( conv5i5ce1 ! classes = :i* ?is text 0 orig9ally prep>$ 7 divid$1 "o "p beg9n+ ) gravimetric processes & ! o!r ) volumetric analyses4 ,aft] a c>eful review ( ! exp]i5ce ?us ga9$ ! conclusion has be5 rea*$ t volumetric analysis (f]s ! bett] approa* to ! subject4 ,accord+ly ! arrangem5t ( ! pres5t 7! six?7 edition ( ?is manual has be5 *ang$ to introduce volumetric proc$ures fir/4 ,tea*]s :o are famili> ) e>li] editions w1 h[ev]1 f9d t ! ord] ( pres5tation ( ! mat]ial "u ! v>i\s divisions is ne>ly ! same z t previ\sly foll[$1 & ^? :o may /ill pref] to beg9 ! c\rse ( in/ruction ) gravimetric processes w1 x is believ$1 be able to foll[ t ord] )\t difficulty4 ,proc$ures = ! det]m9ation ( sulphur 9 insoluble sulphates1 = ! det]m9ation ( copp] 9 copp] ores by iodometric me?ods1 = ! det]m9ation ( iron by p]manganate 9 hydro*loric acid solutions1 & = ! /&>dization ( potassium p]manganate solutions us+ sodium oxalate z a /&>d1 & ( ?iosulphate solutions us+ copp] z a /&>d1 h be5 add$4 ,! det]m9ation ( silica 9 silicates decomposable by acids1 z a sep>ate proc$ure1 has be5 omitt$4 ,! explanatory notes h be5 re>rang$ to br+ !m into clos] association ) ! proc$ures to :i* !y relate4 ,! numb] ( problems has be5 consid]ably increas$4 ,! au?or wi%es to r5ew 8 expressions ( appreciation ( ! k9dly reception accord$ ! e>li] editions ( ?is manual4 ,he has receiv$ helpful sugge/ions f s _m ( 8 colleagues )9 ! ,in/itute1 & fri5ds else:]e1 t 8 s5se ( obligation mu/ be express$ to !m collectively4 ,he is "u special obligations to ,pr(essor ,l4,f4 ,hamilton = assi/ance 9 ! prep>ation ( ! pres5t edition4 ,,h5ry ,p4 ,,talbot 6,massa*usetts ,in/itute ( ,te*nology1 ,septemb]1 #aiba64 ,,cont5ts ,,"p ,i4 ,,introduction ,,subdivisions ,,( ,,analytical ,,*emi/ry ,,g5]al ,,directions ,accuracy & ,economy ( ,"t2 ,notebooks2 ,reag5ts2 ,wa%-bottles2 ,transf] ( ,liquids ,,"p ,,ii4 ,,volumetric ,,analysis ,,g5]al ,,discussion ,subdivisions2 ,! ,analytical ,balance2 ,weights2 ,burettes2 ,calibration ( ,measur+ ,devices ,,g5]al ,,directions ,/&>d & ,normal ,solutions 6,i4 ,neutralization ,me?ods6 ,,alkalimetry ,,& ,,acidimetry ,prep>ation & ,/&>dization ( ,solutions2 ,indicators ,,/&>dization ,,( ,,hydro*loric ,,acid ,,det]m9ation ,,( ,,total ,,alkal9e ,,/r5g? ,,( ,,soda ,,a% ,,det]m9ation ,,( ,,acid ,,/r5g? ,,( ,,oxalic ,,acid 6,,ii4 ,oxidation ,processes6 ,,g5]al ,,discussion ,,bi*romate ,,process ,,= ,,! ,,det]m9ation ,,( ,,iron ,,det]m9ation ,,( ,,iron ,,9 ,,limonite ,,by ,,! ,,bi*romate ,,process ,,det]m9ation ,,( ,,*romium ,,9 ,,*rome ,,iron ,,ore ,,p]manganate ,,process ,,= ,,! ,,det]m9ation ,,( ,,iron ,,det]m9ation ,,( ,,iron ,,9 ,,limonite ,,by ,,! ,,p]manganate ,,process ,,det]m9ation ,,( ,,iron ,,9 ,,limonite ,,by ,,! ,,zimm]mann-,,re9h>dt ,,process ,,det]m9ation ,,( ,,! ,,oxidiz+ ,,p[] ,,( ,,pyrolusite ,,iodimetry ,,det]m9ation ,,( ,,copp] ,,9 ,,ores ,,det]m9ation ,,( ,,antimony ,,9 ,,/ibnite ,,*lorimetry ,,det]m9ation ,,( ,,available ,,*lor9e ,,9 ,,blea*+ ,,p[d] 6,,iii4 ,precipitation ,me?ods6 ,,det]m9ation ,,( ,,silv] ,,by ,,! ,,?iocyanate ,,process ,,"p ,,iii4 ,,gravimetric ,,analysis ,,g5]al ,,directions ,precipitation2 ,funnels & ,filt]s2 ,filtration & ,wa%+ ( ,precipitates2 ,desiccators2 ,crucibles & _! ,prep>ation = ,use2 ,ignition ( ,precipitates ,,det]m9ation ,,( ,,*lor9e ,,9 ,,sodium ,,*loride ,,det]m9ation ,,( ,,iron ,,& ,,( ,,sulphur ,,9 ,,f]r\s ,,ammonium ,,sulphate ,,det]m9ation ,,( ,,sulphur ,,9 ,,b>ium ,,sulphate ,,det]m9ation ,,( ,,phosphoric ,,anhydride ,,9 ,,apatite ,,analysis ,,( ,,lime/one ,det]m9ation ( ,moi/ure2 ,insoluble ,matt] & ,silica2 ,f]ric ,oxide & ,alum9a2 ,calcium2 ,magnesium2 ,c>bon ,dioxide ,,analysis ,,( ,,brass ,electrolytic ,sep>ations2 ,det]m9ation ( ,lead1 ,copp]1 ,iron & ,z9c4 ,,det]m9ation ,,( ,,silica ,,9 ,,silicates ,,"p ,,iv4 ,,/oi*iometry ,,solutions ,,( ,,typical ,,problems ,,problems ,,app5dix ,,electrolytic ,,dissociation ,,!ory ,,fold+ ,,( ,a ,,filt] ,,pap] ,,sample ,,notebook ,,pages ,,/r5g? ,,( ,,reag5ts ,,d5sities ,,& ,,volumes ,,( ,,wat] ,,corrections ,,= ,,*ange ,,( ,,temp]ature ,,( ,,/&>d ,,solutions ,,atomic ,,weights ,,log>i?m ,,tables ,,quantitative ,,*emical ,,analysis ,,"p ,i ,,introduction ,,subdivisions ,,( ,,analytical ,,*emi/ry ,a complete *emical analysis ( a body ( unkn[n composition involves ! recognition ( its compon5t p>ts by ! me?ods ( 6qualitative analysis61 & ! det]m9ation ( ! proportions 9 :i* ^! compon5ts are pres5t by ! processes ( 6quantitative analysis64 ,a prelim9>y qualitative exam9ation is g5]ally indisp5sable1 if intellig5t & prop] provisions are to be made = ! sep>ation ( ! v>i\s con/itu5ts "u su* conditions z w insure accurate quantitative e/imations4 ,x is assum$ t ! op]ations ( qualitative analysis are famili> to ! /ud5t1 :o w f9d t ! reactions made use ( 9 quantitative processes are frequ5tly ! same z ^? employ$ 9 qualitative analyses ) respect to bo? precipitation & sy/ematic sep>ation f int]f]+ sub/ances2 b x %\ld be not$ t ! conditions mu/ n[ be regulat$ ) great] c>e1 & 9 su* a mann] z to insure ! mo/ complete sep>ation possible4 ,= example1 9 ! qualitative detection ( sulphates by precipitation z b>ium sulphate f acid solution x is n necess>y1 9 mo/ in/ances1 to take into acc\nt ! solubility ( ! sulphate 9 hydro*loric acid1 :ile 9 ! quantitative det]m9ation ( sulphates by ?is reaction ?is solubility becomes an important consid]ation4 ,! op]ations ( qualitative analysis are1 !re=e1 ! m accurate ! ne>] !y are made to con=m to quantitative conditions4 ,! me?ods ( quantitative analysis are subdivid$1 accord+ to _! nature1 into ^? ( 6gravimetric analysis1 volumetric analysis61 & 6colorimetric analysis64 ,9 6gravimetric6 processes ! con/itu5t to be det]m9$ is sometimes isolat$ 9 elem5t>y =m1 b m commonly 9 ! =m ( "s comp\nd possess+ a well-e/abli%$ & def9ite composition1 :i* c be readily & completely sep>at$1 & weigh$ ei!r directly or aft] ignition4 ,f ! weight ( ?is sub/ance & its kn[n composition1 ! am\nt ( ! con/itu5t 9 "q is det]m9$4 ,9 6volumetric6 analysis1 in/ead ( ! f9al weigh+ ( a def9ite body1 a well-def9$ reaction is caus$ to take place1 :]e9 ! reag5t is add$ f an app>atus s design$ t ! volume ( ! solution employ$ to complete ! reaction c be accurately measur$4 ,! /r5g? ( ?is solution 7& h5ce its value = ! reaction 9 "q7 is accurately kn[n1 & ! volume employ$ s]ves1 !re=e1 z a measure ( ! sub/ance act$ ^u4 ,an example w make cle> ! di/9ction betwe5 ^! two types ( analysis4 ,! p]c5tage ( *lor9e 9 a sample ( sodium *loride may be det]m9$ by dissolv+ a weigh$ am\nt ( ! *loride 9 wat] & precipitat+ ! *loride ions z silv] *loride1 :i* is !n sep>at$ by filtration1 ignit$1 & weigh$ 7a 6gravimetric6 process72 or ! sodium *loride may be dissolv$ 9 wat]1 & a solution ( silv] nitrate conta9+ an accurately kn[n am\nt ( ! silv] salt 9 ea* cubic c5timet] may be cauti\sly add$ f a measur+ device call$ a burette until precipitation is complete1 :5 ! am\nt ( *lor9e may be calculat$ f ! numb] ( cubic c5timet]s ( ! silv] nitrate solution involv$ 9 ! reaction4 ,?is is a 6volumetric6 process1 & is equival5t to weigh+ )\t ! use ( a balance4 ,volumetric me?ods are g5]ally m rapid1 require less app>atus1 & are frequ5tly capable ( great] accuracy ?an gravimetric me?ods4 ,!y are p>ticul>ly useful :5 _m det]m9ations ( ! same sort are requir$4 ,9 6colorimetric6 analyses ! sub/ance to be det]m9$ is conv]t$ into "s comp\nd :i* imp>ts to its solutions a di/9ct color1 ! int5sity ( :i* mu/ v>y 9 direct proportion to ! am\nt ( ! comp\nd 9 ! solution4 ,su* solutions are comp>$ ) respect to dep? ( color ) /&>d solutions conta9+ kn[n am\nts ( ! color$ comp\nd1 or ( o!r simil> color-produc+ sub/ance :i* has be5 f\nd acceptable z a color /&>d4 ,colorimetric me?ods are1 9 g5]al1 re/rict$ to ! det]m9ations ( v small quantities1 s9ce only 9 dilute solutions are accurate comp>isons ( color possible4 ,,g5]al ,,directions ,! foll[+ p>agraphs %\ld be read c>efully & ?\ghtfully4 ,a prime ess5tial = success z an analy/ is att5tion to details & ! avoidance ( all conditions :i* c\ld de/roy1 or ev5 less51 confid5ce 9 ! analyses :5 complet$4 ,! sugge/ions "h giv5 are ! outcome ( mu* exp]i5ce1 & _! adoption w t5d to insure p]man5tly "w ( a high grade1 :ile neglect ( !m w (t5 lead to disappo9tm5t & loss ( "t4 ,,accuracy ,,& ,,economy ,,( ,,"t ,! fundam5tal conception ( quantitative analysis implies a necessity = all possible c>e 9 gu>d+ aga9/ loss ( mat]ial or ! introduction ( =eign matt]4 ,! laboratory desk1 & all app>atus1 %\ld be scrupul\sly neat & clean at all times4 ,a sponge %\ld always be ready at h&1 & desk & filt]-/&s %\ld be kept dry & 9 good ord]4 ,funnels %\ld nev] be all[$ to drip ^u ! base ( ! /&4 ,glassw>e %\ld always be wip$ ) a clean1 l9tless t[el j be=e use4 ,all filt]s & solutions %\ld be cov]$ to protect !m f du/1 j z f> z is practicable1 & e drop ( solution or p>ticle ( precipitate mu/ be reg>d$ z invaluable = ! success ( ! analysis4 ,an economical use ( laboratory h\rs is be/ secur$ by acquir+ a ?or\gh k ( ! "* ( ! "w to be done be=e und]tak+ x1 & !n by s arrang+ ! "w t no "t %all be wa/$ dur+ ! evaporation ( liquids & l "t-consum+ op]ations4 ,to ?is end ! /ud5t %\ld read ?\ghtfully n only ! 6entire6 proc$ure1 b ! explanatory notes z well1 be=e any /ep is tak5 9 ! analysis4 ,! explanatory notes furni%1 9 g5]al1 ! reasons = p>ticul> /eps or precautions1 b !y also occasionally conta9 details ( manipulation n incorporat$1 = v>i\s reasons1 9 ! proc$ure4 ,^! notes foll[ ! proc$ures at frequ5t int]vals1 & ! exact po9ts to :i* !y apply are indicat$ by ref]5ces4 ,! /ud5t %\ld realize t a 6failure to /udy ! notes w inevitably lead to mi/akes1 loss ( "t1 & an inadequate und]/&+ ( ! subject64 ,all analyses %\ld be made 9 duplicate1 & 9 g5]al a close agreem5t ( results %\ld be expect$4 ,x %\ld1 h[ev]1 be rememb]$ t a close concordance ( results 9 *eck analyses is n conclusive evid5ce ( ! accuracy ( ^? results1 al?\gh ! probability ( _! accuracy is1 ( c\rse1 consid]ably enhanc$4 ,! satisfaction 9 obta9+ *eck results 9 su* analyses mu/ nev] be all[$ to int]f]e ) ! critical exam9ation ( ! proc$ure employ$1 nor mu/ !y ev] be reg>d$ z 9 any measure a sub/itute = absolute tru? & accuracy4 ,9 ?is connection x mu/ also be emphasiz$ t only ! op]ator himself c "k ! :ole hi/ory ( an analysis1 & only he c "k :e!r 8 "w is wor?y ( full confid5ce4 ,no "w %\ld be cont9u$ = a mom5t aft] su* confid5ce is lo/1 b %\ld be resolutely disc>d$ z soon z a cause = di/ru/ is fully e/abli%$4 ,! /ud5t %\ld1 h[ev]1 det]m9e to put =? 8 be/ ef=ts 9 ea* analysis2 x is well n to be too ready to condone failures & to beg9 aga91 z mu* "t is lo/ 9 ^! fruitless attempts4 ,no?+ less ?an 6absolute integrity6 is or c be dem&$ ( a quantitative analy/1 & any disreg>d ( ?is pr9ciple1 h[ev] slight1 is z fatal to success z lack ( *emical k or inaptitude 9 manipulation c possibly be4 ,,notebooks ,notebooks %\ld conta91 beside ! record ( obs]vations1 descriptive notes4 ,all records ( weights %\ld be plac$ ^u ! "r-h& page1 :ile t on ! left is res]v$ = ! notes1 calculations ( factors1 or ! am\nt ( reag5ts requir$4 ,! neat & sy/ematic arrangem5t ( ! records ( analyses is ( ! fir/ importance1 & is an evid5ce ( c>eful "w & an excell5t cr$5tial4 ,( two notebooks 9 :i* ! results may be1 9 fact1 ( equal value z legal evid5ce1 t "o :i* is neatly arrang$ w c>ry ) x great] weight4 ,all records %\ld be dat$1 & all obs]vations %\ld be record$ at once 9 ! notebook4 ,! mak+ ( records ^u loose pap] is a practice to be deprecat$1 z is also t ( copy+ orig9al entries into a second notebook4 ,! /ud5t %\ld accu/om himself to ord]ly entries at ! "t ( obs]vation4 ,sev]al sample pages ( sy/ematic records are to be f\nd 9 ! ,app5dix4 ,^! are bas$ ^u exp]i5ce2 b o!r arrangem5ts1 if cle> & ord]ly1 may prove equally s]viceable4 ,! /ud5t is advis$ to foll[ ! sample pages until he is 9 a position to plan out a sy/em ( 8 own4 ,,reag5ts ,! habit ( c>efully te/+ reag5ts1 includ+ di/ill$ wat]1 _c be too e>ly acquir$ or too con/antly practic$2 =1 9 spite ( all reasonable precaution>y measures1 inf]ior *emicals w occasionally f9d _! way into ! /ock room1 or errors w be made 9 fill+ reag5t bottles4 ,! /ud5t %\ld rememb] t :ile !re may be o!rs :o %>e ! responsibility = ! purity ( mat]ials 9 ! laboratory ( an in/itution1 ! responsibility w lat] be "o :i* he mu/ individually assume4 ,! /opp]s ( reag5t bottles %\ld nev] be laid ^u ! desk1 unless ^u a clean wat*-glass or pap]4 ,! neck & m\? ( all su* bottles %\ld be kept scrupul\sly clean1 & c>e tak5 t no confusion ( /opp]s occurs4 ,,wa%-,,bottles ,wa%-bottles = di/ill$ wat] %\ld be made f flasks ( ab\t #gej cc4 capacity & be provid$ ) gracefully b5t tubes1 :i* %\ld n be too long4 ,! jet %\ld be connect$ ) ! tube ent]+ ! wa%-bottle by a %ort piece ( rubb] tub+ 9 su* a way z to be flexible1 & %\ld deliv] a /ream ab\t "o millimet] 9 diamet]4 ,! neck ( ! flask may be w\nd ) cord1 or cov]$ ) wa%-lea!r1 = great] com=t :5 hot wat] is us$4 ,x is well to provide sev]al small wa%-bottles = liquids o!r ?an di/ill$ wat]1 :i* %\ld inv>iably be cle>ly label$4 ,,transf] ,,( ,,liquids ,liquids %\ld nev] be transf]r$ f "o vessel to ano!r1 nor to a filt]1 )\t ! aid ( a /irr+ rod held firmly aga9/ ! side or lip ( ! vessel4 ,:5 ! vessel is provid$ ) a lip x is n usually necess>y to use o!r means to prev5t ! loss ( liquid by runn+ d[n ! side2 :5ev] loss seems imm95t a 6v ?96 lay] ( vasel9e1 appli$ ) ! f+] to ! edge ( ! vessel1 w prev5t x4 ,! /irr+ rod d[n :i* ! liquid runs %\ld nev] be drawn upw>d 9 su* a way z to all[ ! solution to collect on ! "u side ( ! rim or lip ( a vessel4 ,! numb] ( transf]s ( liquids f "o vessel to ano!r dur+ an analysis %\ld be z small z possible to avoid ! risk ( slight losses4 ,ea* vessel mu/1 ( c\rse1 be completely wa%$ to insure ! transf] ( all mat]ial2 b x %\ld be rememb]$ t ?is c be accompli%$ bett] by ! use ( successive small portions ( wa%-wat] 7p]haps #e-aj cc471 if ea* wa%-wat] is all[$ to dra9 away = a few seconds1 ?an by ! addition ( l>ge am\nts :i* unnecess>ily increase ! volume ( ! solutions1 caus+ loss ( "t 9 subsequ5t filtrations or evaporations4 ,all /irr+ rods employ$ 9 quantitative analyses %\ld be r\nd$ at ! ends by hold+ !m 9 ! flame ( a burn] until !y beg9 to s(t54 ,if ?is is n done1 ! rods w scrat* ! inn] surface ( beak]s1 caus+ !m to crack on subsequ5t heat+4 ,,evaporation ,,( ,,liquids ,! greate/ c>e mu/ be tak5 to prev5t loss ( solutions dur+ processes ( evaporation1 ei!r f too viol5t ebullition1 f evaporation to dryness & spatt]+1 or f ! evolution ( gas dur+ ! heat+4 ,9 g5]al1 evaporation ^u ! /eam ba? is to be pref]r$ to o!r me?ods on acc\nt ( ! impossibility ( loss by spatt]+4 ,if ! /eam ba?s are well protect$ f du/1 solutions %\ld be left )\t cov]s dur+ evaporation2 b solutions :i* are boil$ ^u ! hot plate1 or f :i* gases are escap+1 %\ld inv>iably be cov]$4 ,9 any case a wat*-glass may be support$ above ! vessel by means ( a glass triangle1 or o!r simil> device1 & ! dang] ( loss ( mat]ial or contam9ation by du/ ?us be avoid$4 ,x is obvi\s t evaporation is promot$ by ! use ( vessels :i* admit ( ! exposure ( a broad surface to ! air4 ,liquids :i* conta9 susp5d$ matt] 7precipitates7 %\ld always be cauti\sly heat$1 s9ce ! pres5ce ( ! solid matt] is frequ5tly ! occasion ( viol5t bump+1 ) consequ5t risk to app>atus & analysis4 ,,"p ,,ii ,,volumetric ,,analysis ,! processes ( volumetric analysis are1 9 g5]al1 simpl] ?an ^? ( gravimetric analysis & accord+ly s]ve be/ z an introduction to ! practice ( quantitative analysis4 ,= _! execution !re are requir$1 fir/1 an accurate balance ) :i* to weigh ! mat]ial = analysis2 second1 graduat$ in/rum5ts 9 :i* to measure ! volume ( ! solutions employ$2 ?ird1 /&>d solutions1 t is1 solutions ! value ( :i* is accurately kn[n2 & f\r?1 indicators1 :i* w furni% accurate evid5ce ( ! po9t at :i* ! desir$ reaction is complet$4 ,! nature ( ! indicators employ$ w be expla9$ 9 connection ) ! diff]5t analyses4 ,! process :]eby a 6/&>d solution6 is br\ght into reaction is call$ 6titration61 & ! po9t at :i* ! reaction is exactly complet$ is call$ ! 6end-po9t64 ,! 6indicator6 %\ld %[ ! 6end-po9t6 ( ! 6titration64 ,! volume ( ! /&>d solution us$ !n furni%es ! measure ( ! sub/ance to be det]m9$ z truly z if t sub/ance _h be5 sep>at$ & weigh$4 ,! processes ( volumetric analysis are easily classifi$1 accord+ to _! "*1 into3 ,i4 ,,neutralization ,,me?ods2 su*1 = example1 z ^? ( acidimetry & alkalimetry4 ,,ii4 ,,oxidation ,,processes2 z exemplifi$ 9 ! det]m9ation ( f]r\s iron by its oxidation ) potassium bi*romate4 ,,iii4 ,,precipitation ,,me?ods2 ( :i* ! titration = silv] ) potassium ?iocyanate solution is an illu/ration4 ,f a some:at diff]5t /&po9t ! me?ods 9 ea* case may be subdivid$ into 7a7 ,,direct ,,me?ods1 9 :i* ! sub/ance to be measur$ is directly det]m9$ by titration to an end-po9t ) a /&>d solution2 & 7b7 ,,indirect ,,me?ods1 9 :i* ! sub/ance itself is n measur$1 b a quantity ( reag5t is add$ :i* is kn[n to be an excess ) respect to a specific reaction1 & ! unus$ excess det]m9$ by titration4 ,examples ( ! latt] class w be po9t$ out z !y occur 9 ! proc$ures4 ,,measur+ ,,in/rum5ts ,,! ,,analytical ,,balance ,= a complete discussion ( ! physical pr9ciples und]ly+ ! con/ruction & use ( balances1 & ! v>i\s me?ods ( weigh+1 ! /ud5t is ref]r$ to l>g] manuals ( ,quantitative ,analysis1 su* z ^? ( ,fres5ius1 or ,treadwell-,hall1 & p>ticul>ly to ! admirable discussion ( ?is topic 9 ,morse's 6,ex]cises 9 ,quantitative ,*emi/ry64 ,! /atem5ts & rules ( proc$ure :i* foll[ are suffici5t = ! intellig5t use ( an analytical balance 9 connection ) processes prescrib$ 9 ?is introductory manual4 ,x is1 h[ev]1 imp]ative t ! /ud5t %\ld make himself famili> ) ^! ess5tial features ( ! balance1 & its use4 ,he %\ld fully realize t ! analytical balance is a delicate in/rum5t :i* w r5d] excell5t s]vice "u c>eful treatm5t1 b su* treatm5t is an ess5tial condition if its accuracy is to be dep5d$ ^u4 ,he %\ld also und]/& t no set ( rules1 h[ev] complete1 c d away ) ! necessity = a s5se ( p]sonal responsibility1 s9ce by c>elessness he c r5d] inaccurate n only 8 own analyses1 b ^? ( all o!r /ud5ts us+ ! same balance4 ,be=e mak+ any weigh+s ! /ud5t %\ld seat himself be=e a balance & obs]ve ! foll[+ details ( con/ruction3 #a4 ,! balance case is m\nt$ on ?ree brass legs1 :i* %\ld pref]ably re/ 9 glass cups1 back$ ) rubb] to prev5t slipp+4 ,! front legs are adju/able z to height & are us$ to level ! balance case2 ! re> leg is ( p]man5t l5g?4 #b4 ,! front ( ! case may be rais$ to give access to ! balance4 ,9 "s makes doors are provid$ also at ! ends ( ! balance case4 #c4 ,! balance beam is m\nt$ ^u an upright 9 ! c5t] ( ! case on ! top ( :i* is an inlaid agate plate4 ,to ! c5t] ( ! beam !re is atta*$ a /eel or agate knife-edge on :i* ! beam oscillates :5 x re/s on ! agate plate4 #d4 ,! balance beam1 ext5d+ to ! "r & left1 is graduat$ along its upp] edge1 usually on bo? sides1 & has at its extremities two agate or /eel knife-edges f :i* are susp5d$ /irrups4 ,ea* ( ^! /irrups has an agate plate :i*1 :5 ! balance is 9 action1 re/s ^u ! correspond+ knife-edge ( ! beam4 ,! balance pans are susp5d$ f ! /irrups4 #e4 ,a po9t] is atta*$ to ! c5t] ( ! beam1 & z ! beam oscillates ?is po9t] moves 9 front ( a scale ne> ! base ( ! po/4 #f4 ,at ! base ( ! po/1 usually 9 ! re>1 is a _s-level4 #g4 ,)9 ! upright is a me*anism1 controll$ by a knob at ! front ( ! balance case1 :i* is s arrang$ z to raise ! entire beam slightly above ! level at :i* ! knife-edges are 9 contact ) ! agate plates4 ,:5 ! balance is n 9 use ! beam mu/ be support$ by ?is device s9ce1 o!rwise1 ! con/ant j>r+ to :i* a balance is inevitably subject$1 w soon dull ! knife-edges1 & less5 ! s5sitiv5ess ( ! balance4 #h4 ,a small weight1 or bob1 is atta*$ to ! po9t] 7or sometimes to ! beam7 by :i* ! c5t] ( gravity ( ! beam & its atta*m5ts may be regulat$4 ,! c5t] ( gravity mu/ lie v slightly bel[ ! level ( ! agate plates to secure ! desir$ s5sitiv5ess ( ! balance4 ,?is is provid$ = :5 ! balance is set up & v r>ely requires alt]ation4 ,! /ud5t %\ld nev] attempt to *ange ?is adju/m5t4 #i4 ,bel[ ! balance pans are two pan-arre/s op]at$ by a button f ! front ( ! case4 ,^! arre/s ex]t a v slight upw>d pressure ^u ! pans & m9imize ! displacem5t ( ! beam :5 objects or weights are be+ plac$ ^u ! pans4 #aj4 ,a movable rod1 op]at$ f "o end ( ! balance case1 ext5ds ov] ! balance beam & c>ries a small wire weight1 call$ a rid]4 ,by means ( ?is rod ! rid] c be plac$ ^u any desir$ division ( ! scale on ! balance beam4 ,ea* numb]$ division on ! beam corresponds to "o milligram1 & ! use ( ! rid] obviates ! plac+ ( v small fractional weights on ! balance pan4 ,if a new rid] is pur*as$1 or an old "o replac$1 c>e mu/ be tak5 t its weight corresponds to ! graduations on ! beam ( ! balance on :i* x is to be us$4 ,! weight ( ! rid] 9 milligrams mu/ be equal to ! numb] ( l>ge divisions 7#e1 #f1 #aj1 or #ab7 betwe5 ! c5tral knife-edge & ! knife-edge at ! end ( ! beam4 ,x %\ld be not$ t on "s balances ! la/ division be>s no numb]4 ,ea* new rid] %\ld be te/$ aga9/ a #e or #aj-milligram weight4 ,9 "s ( ! mo/ rec5t =ms ( ! balance a *a9 device replaces ! small] weights & ! use ( ! rid] z j describ$4 ,be=e us+ a balance1 x is always be/ to te/ its adju/m5t4 ,?is is absolutely necess>y if ! balance is us$ by sev]al work]s2 x is always a wise precaution "u any conditions4 ,= ?is purpose1 bru% (f ! balance pans ) a s(t camel's hair bru%4 ,!n note 7#a7 :e!r ! balance is level2 7#b7 t ! me*anism = rais+ & l[]+ ! beams works smoo?ly2 7#c7 t ! pan-arre/s t\* ! pans :5 ! beam is l[]$2 & 7#d7 t ! ne$le sw+s equal di/ances on ei!r side ( ! z]o-po9t :5 set 9 motion )\t any load on ! pans4 ,if ! latt] condition is n fulfill$1 ! balance %\ld be adju/$ by means ( ! adju/+ screw at ! end ( ! beam unless ! v>iation is n m ?an "o division on ! scale2 x is (t5 bett] to make a prop] all[ance = ?is small z]o error ?an to di/urb ! balance by an attempt at correction4 ,unless a /ud5t ?or\ghly und]/&s ! con/ruction ( a balance he %\ld nev] attempt to make adju/m5ts1 b %\ld apply to ! in/ructor 9 *>ge4 ,! object to be weigh$ %\ld be plac$ on ! left-h& balance pan & ! weights ^u ! "r-h& pan4 ,e sub/ance :i* c\ld attack ! metal ( ! balance pan %\ld be weigh$ ^u a wat*-glass1 & all objects mu/ be dry & cold4 ,a w>m body gives rise to air curr5ts :i* vitiate ! accuracy ( ! weigh+4 ,! weights %\ld be appli$ 9 ! ord] 9 :i* !y occur 9 ! weight-box 7n at haphaz>d71 beg9n+ ) ! l>ge/ weight :i* is app>5tly requir$4 ,aft] a weight has be5 plac$ ^u ! pan ! beam %\ld be l[]$ ^u its knife-edges1 &1 if necess>y1 ! pan-arre/s depress$4 ,! movem5t ( ! po9t] w !n indicate :e!r ! weight appli$ is too great or too small4 ,:5 ! weight has be5 asc]ta9$1 by ! successive addition ( small weights1 to ! ne>e/ #e or #aj milligrams1 ! weigh+ is complet$ by ! use ( ! rid]4 ,! correct weight is t :i* causes ! po9t] to sw+ an equal numb] ( divisions to ! "r & left ( ! z]o-po9t1 :5 ! po9t] trav]ses n less ?an five divisions on ei!r side4 ,! balance case %\ld always be clos$ dur+ ! f9al weigh+1 :ile ! rid] is be+ us$1 to protect ! pans f ! effect ( air curr5ts4 ,be=e ! f9al det]m9ation ( an exact weight ! beam %\ld always be lift$ f ! knife-edges & aga9 l[]$ into place1 z x frequ5tly happ5s t ! scale pans are1 9 spite ( ! pan-arre/s1 slightly twi/$ by ! impact ( ! weights1 ! beam be+ !reby virtually l5g!n$ or %ort5$4 ,lift+ ! beam re/ores ! prop] alignm5t4 ,! beam %\ld nev] be set 9 motion by l[]+ x =cibly ^u ! knife-edges1 nor by t\*+ ! pans1 b r by lift+ ! rid] 7unless ! balance be provid$ ) "s ( ! new] devices = ! purpose71 & ! sw+ %\ld be arre/$ only :5 ! ne$le approa*es z]o on ! scale1 o!rwise ! knife-edges become dull4 ,= ! same reason ! beam %\ld nev] be left ^u its knife-edges1 nor %\ld weights be remov$ f or plac$ on ! pans )\t support+ ! beam1 except 9 ! case ( ! small fractional weights4 ,:5 ! process ( weigh+ has be5 complet$1 ! weight %\ld be record$ 9 ! notebook by fir/ not+ ! vacant spaces 9 ! weight-box1 & !n *eck+ ! weight by aga9 not+ ! weights z !y are remov$ f ! pan4 ,?is practice w (t5 detect & avoid errors4 ,x is obvi\s t ! weights %\ld always be return$ to _! prop] places 9 ! box1 & be h&l$ only ) p9c]s4 ,x %\ld be borne 9 m9d t if ! me*anism ( a balance is d]ang$ or if any sub/ance is spill$ ^u ! pans or 9 ! balance case1 ! damage %\ld be report$ at once4 ,9 _m in/ances s]i\s h>m c be av]t$ by prompt action :5 delay might ru9 ! balance4 ,samples = analysis are commonly weigh$ 9 small tubes ) cork /opp]s4 ,s9ce ! /opp]s are likely to *ange 9 weight f ! v>y+ am\nts ( moi/ure absorb$ f ! atmosph]e1 x is necess>y to confirm ! record$ weight ( a tube :i* has be5 unus$ = "s "t be=e weigh+ out a new portion ( sub/ance f x4 ,,weights ,! sets ( weights commonly us$ 9 analytical *emi/ry range f #bj grams to #e milligrams4 ,! weights f #bj grams to #a gram are usually ( brass1 lacqu]$ or gold plat$4 ,! fractional weights are ( ,g]man silv]1 gold1 plat9um or alum9ium4 ,! rid] is ( plat9um or alum9ium wire4 ,! sets ( weights pur*as$ f reputable deal]s are usually suffici5tly accurate = analytical "w4 ,x is n necess>y t su* a set %\ld be /rictly exact 9 comp>ison ) ! absolute /&>d ( weight1 provid$ !y are relatively correct among !mselves1 & provid$ ! same set ( weights is us$ 9 all weigh+s made dur+ a giv5 analysis4 ,! analy/ %\ld assure himself t ! weights 9 a set previ\sly unfamili> to him are relatively correct by a few simple te/s4 ,= example1 he %\ld make sure t 9 8 set two weights ( ! same d5om9ation 7i4e41 two #aj-;gram weights1 or ! two #ajj-milligram weights7 are actually equal & int]*angeable1 or t ! #ejj-milligram weight is equal to ! sum ( ! #bjj1 #ajj1 #ajj1 #ej1 #bj1 #bj & #aj-milligram weights comb9$1 & s on4 ,if discrepancies ( m ?an a few t5?s ( a milligram 7dep5d+ ^u ! total weight involv$7 are f\nd1 ! weights %\ld be return$ = correction4 ,! rid] %\ld also be comp>$ ) a #e or #aj-milligram weight4 ,9 an in/ructional laboratory appreciable errors %\ld be report$ to ! in/ructor 9 *>ge = 8 consid]ation4 ,:5 ! highe/ accuracy is desir$1 ! weights may be calibrat$ & corrections appli$4 ,a calibration proc$ure is describ$ 9 a pap] by ,t4,w4 ,ri*>ds1 6,j4 ,am4 ,*em4 ,soc461 #bb1 #add1 & 9 _m l>ge text-books4 ,weights are inevitably subject to corrosion if n prop]ly protect$ at all times1 & are liable to damage unless h&l$ ) great c>e4 ,x is obvi\s t any?+ :i* alt]s ! weight ( a s+le piece 9 an analytical set w introduce an error 9 e weigh+ made 9 :i* t piece is us$4 ,?is s\rce ( error is (t5 extremely obscure & difficult to detect4 ,! only safegu>d aga9/ su* errors is to be f\nd 9 scrupul\s c>e 9 h&l+ & protection on ! "p ( ! analy/1 & an equal insi/5ce t if sev]al analy/s use ! same set ( weights1 ea* %all realize 8 responsibility = ! "w ( o!rs z well z 8 own4 ,,burettes ,a burette is made f a glass tube :i* is z uni=mly cyl9drical z possible1 & ( su* a bore t ! divisions :i* are et*$ ^u its surface %all correspond closely to actual cont5ts4 ,! tube is contract$ at "o extremity1 & t]m9ates 9 ei!r a glass /opcock & deliv]y-tube1 or 9 su* a mann] t a piece ( rubb] tub+ may be firmly atta*$1 connect+ a deliv]y-tube ( glass4 ,! rubb] tub+ is clos$ by means ( a glass bead4 ,burettes ( ! latt] type w be ref]r$ to z pla9 burettes4 ,! graduations are usually numb]$ 9 cubic c5timet]s1 & ! latt] are subdivid$ into t5?s4 ,"o burette ( ea* type is desirable = ! analytical proc$ures :i* foll[4 ,,prep>ation ,,( ,a ,,burette ,,= ,,use ,! inn] surface ( a burette mu/ be ?or\ghly clean$ 9 ord] t ! liquid z drawn out may dra9 away completely1 )\t leav+ drops ^u ! sides4 ,?is is be/ accompli%$ by treat+ ! inside ( ! burette ) a w>m solution ( *romic acid 9 conc5trat$ sulphuric acid1 appli$ z foll[s3 ,if ! burette is ( ! pla9 type1 fir/ remove ! rubb] tip & =ce ! l[] end ( ! burette into a m$ium-siz$ cork /opp]4 ,ne>ly fill ! burette ) ! *romic acid solution1 close ! upp] end ) a cork /opp] & tip ! burette backw>d & =w>d 9 su* a way z to br+ ! solution into contact ) ! entire inn] surface4 ,remove ! /opp] & p\r ! solution into a /ock bottle to be kept = fur!r use1 & r9se out ! burette ) wat] sev]al times4 ,unless ! wat] !n runs freely f ! burette )\t leav+ drops adh]+ to ! sides1 ! process mu/ be repeat$ 7,note #a74 ,if ! burette has a glass /opcock1 ?is %\ld be remov$ aft] ! clean+ & wip$1 & also ! inside ( ! gr\nd jo9t4 ,! surface ( ! /opcock %\ld !n be sme>$ ) a ?9 coat+ ( vasel9e & replac$4 ,x %\ld be atta*$ to ! burette by means ( a wire1 or ela/ic b&1 to less5 ! dang] ( breakage4 ,fill ! burettes ) di/ill$ wat]1 & all[ ! wat] to run out ?r\gh ! /opcock or rubb] tip until conv9c$ t no air bubbles are inclos$ 7,note #b74 ,fill ! burette to a po9t above ! z]o-po9t & draw (f ! wat] until ! m5iscus is j bel[ t m>k4 ,x is !n ready = calibration4 ,note #a3 ,! inn] surface ( ! burette mu/ be absolutely clean if ! liquid is to run (f freely4 ,*romic acid 9 sulphuric acid is usually f\nd to be ! be/ cleans+ ag5t1 b ! mixture mu/ be w>m & conc5trat$4 ,! solution c be prep>$ by p\r+ ov] a few cry/als ( potassium bi*romate a little wat] & !n add+ conc5trat$ sulphuric acid4 ,note #b3 ,x is always necess>y to insure ! abs5ce ( air bubbles 9 ! tips or /opcocks4 ,! treatm5t describ$ above w usually accompli% ?is1 b1 9 ! case ( pla9 burettes x is sometimes bett] to all[ a little ( ! liquid to fl[ out ( ! tip :ile x is b5t upw>ds4 ,any air :i* may be entrapp$ !n rises ) ! liquid & escapes4 ,if air bubbles escape dur+ subsequ5t calibration or titration1 an error is introduc$ :i* vitiates ! results4 ,,read+ ,,( ,a ,,burette ,all liquids :5 plac$ 9 a burette =m :at is call$ a m5iscus at _! upp] surfaces4 ,9 ! case ( liquids su* z wat] or aque\s solutions ?is m5iscus is concave1 & :5 ! liquids are transp>5t accurate read+s are be/ obta9$ by obs]v+ ! position on ! graduat$ scales ( ! l[e/ po9t ( ! m5iscus4 ,?is c be/ be done z foll[s3 ,wrap ar\nd ! burette a piece ( color$ pap]1 ! /raight1 smoo? edges ( :i* are held ev5ly toge!r ) ! color$ side next to ! burette 7,note #a74 ,hold ! pap] ab\t two small divisions bel[ ! m5iscus & raise or l[] ! level ( ! eyes until ! edge ( ! pap] at ! back ( ! burette is j hidd5 f ! eye by t 9 front 7,note #b74 ,note ! position ( ! l[e/ po9t ( ! curve ( ! m5iscus1 e/imat+ ! t5?s ( ! small divisions1 ?us read+ its position to hundr$?s ( a cubic c5timet]4 ,note #a3 ,! ends ( ! color$ pap] us$ z an aid to accurate read+s may be fa/5$ toge!r by means ( a gumm$ label4 ,! pap] may !n rema9 on ! burette & be ready = imm$iate use by slid+ x up or d[n1 z requir$4 ,note #b3 ,to obta9 an accurate read+ ! eye mu/ be v ne>ly on a level ) ! m5iscus4 ,?is is secur$ by ! use ( ! pap] z describ$4 ,! /ud5t %\ld obs]ve by trial h[ a read+ is affect$ :5 ! m5iscus is view$ f above or bel[4 ,! eye soon becomes accu/om$ to e/imat+ ! t5?s ( ! divisions4 ,if ! pap] is held z direct$1 two divisions bel[ ! m5iscus1 "o :ole division is visible to correct ! judgm5t4 ,x is n well to attempt to br+ ! m5iscus exactly to a division m>k on ! burette4 ,su* read+s are usually less accurate ?an ^? 9 :i* ! t5?s ( a division are e/imat$4 ,,calibration ,,( ,,glass ,,measur+ ,,devices ,if accuracy ( results is to be atta9$1 ! correctness ( all measur+ in/rum5ts mu/ be te/$4 ,none ( ! app>atus (f]$ = sale c be implicitly reli$ ^u except ^? m exp5sive in/rum5ts :i* are accompani$ by a c]tificate f ! 6,national ,bureau ( ,/&>ds6 at ,wa%+ton1 or o!r equally au!ntic s\rce4 ,! bore ( burettes is subject to accid5tal v>iations1 & s9ce ! graduations are appli$ by ma*9e )\t reg>d to su* v>iations ( bore1 local errors result4 ,! process ( te/+ ^! in/rum5ts is call$ 6calibration64 ,x is usually accompli%$ by comp>+ ! actual weight ( wat] conta9$ 9 ! in/rum5t ) its app>5t volume4 ,!re is1 un=tunately1 no uni=m /&>d ( volume :i* has be5 adopt$ = g5]al use 9 all laboratories4 ,x has be5 v>i\sly propos$ to consid] ! volume ( #ajjj grams ( wat] at #d1 #ae4e1 #af1 #ag4e1 & ev5 #bj;,c41 z a lit] = practical purposes1 & to consid] ! cubic c5timet] to be "o "o-?\s&? ( t volume4 ,! true lit] is ! volume ( #ajjj grams ( wat] at #d;,c42 b ?is is obvi\sly a l[] temp]ature ?an t commonly f\nd 9 laboratories1 & involves ! con/ant use ( corrections if tak5 z a laboratory /&>d4 ,_m laboratories use #ae4e;,c4 7#fj ,f47 z ! work+ /&>d4 ,x is pla9 t any temp]ature :i* is deem$ mo/ conv5i5t might be *os5 = a p>ticul> laboratory1 b x _c be too /rongly emphasiz$ t all measur+ in/rum5ts1 includ+ burettes1 pipettes1 & flasks1 %\ld be calibrat$ at t temp]ature 9 ord] t ! cont5ts ( ea* burette1 pipette1 etc41 %all be comp>able ) t ( e o!r in/rum5t1 ?us p]mitt+ g5]al int]*ange & sub/itution4 ,= example1 x is obvi\s t if x is desir$ to remove exactly #ej cc4 f a solution :i* has be5 dilut$ to #ejj cc4 9 a graduat$ flask1 ! #ej cc4 flask or pipette us$ to remove ! fractional portion mu/ give a correct read+ at ! same temp]ature z ! #ejj cc4 flask4 ,simil>ly1 a burette us$ = ! titration ( ! #ej cc4 ( solution remov$ %\ld be calibrat$ "u ! same conditions z ! measur+ flasks or pipettes employ$ ) x4 ,! /ud5t %\ld also keep con/antly 9 m9d ! fact t all volumetric op]ations1 to be exact1 %\ld be c>ri$ out z ne>ly at a con/ant temp]ature z is practicable4 ,! spot select$ = su* "w %\ld !re=e be subject to a m9imum ( temp]ature v>iations1 & %\ld h z ne>ly ! av]age temp]ature ( ! laboratory z is possible4 ,9 all "w1 :e!r ( calibration1 /&>dization1 or analysis1 ! temp]ature ( ! liquids employ$ mu/ be tak5 into acc\nt1 & if ! temp]ature ( ^! liquids v>ies m ?an #c or #d f ! /&>d temp]ature *os5 = ! laboratory1 corrections mu/ be appli$ = errors due to expansion or contraction1 s9ce volumes ( a liquid measur$ at diff]5t times are comp>able only "u l conditions z to temp]ature4 ,data to be us$ = ?is purpose are giv5 9 ! ,app5dix4 ,neglect ( ?is correction is frequ5tly an avoidable s\rce ( error & annoyance 9 o!rwise excell5t "w4 ,! temp]ature ( all solutions at ! "t ( /&>dization %\ld be record$ to facilitate ! application ( temp]ature corrections1 if su* are necess>y at any lat] "t4 ,,calibration ,,( ,,! ,,burettes ,two burettes1 "o at lea/ ( :i* %\ld h a glass /opp]1 are requir$ ?r\gh\t ! volumetric "w4 ,bo? burettes %\ld be calibrat$ by ! /ud5t to :om !y are assign$4 ,,proc$ure4--,weigh a #ej cc41 flat-bottom$ flask 7pref]ably a light-weight flask71 :i* mu/ be dry on ! outside1 to ! ne>e/ c5tigram4 ,record ! weight 9 ! notebook4 7,see ,app5dix = sugge/ions z to records47 ,place ! flask "u ! burette & draw out into x ab\t #aj cc4 ( wat]1 remov+ any drop on ! tip by t\*+ x aga9/ ! inside ( ! neck ( ! flask4 ,d n attempt to /op exactly at ! #aj cc4 m>k1 b d n v>y m ?an #j4a cc4 f x4 ,note ! "t1 & at ! expiration ( ?ree m9utes 7or long]7 read ! burette accurately1 & record ! read+ 9 ! notebook 7,note #a74 ,mean:ile weigh ! flask & wat] to c5tigrams & record its weight 7,note #b74 ,draw (f ! liquid f #aj cc4 to ab\t #bj cc4 into ! same flask )\t empty+ x2 weigh1 & at ! expiration ( ?ree m9utes take ! read+1 & s on ?r\gh\t ! l5g? ( ! burette4 ,:5 x is complet$1 refill ! burette & *eck ! fir/ calibration4 ,! diff]5ces 9 read+s repres5t ! app>5t volumes1 ! diff]5ces 9 weights ! true volumes4 ,= example1 if an app>5t volume ( #aj4je cc4 is f\nd to weigh #aj4jc grams1 x may be assum$ ) suffici5t accuracy t ! error 9 t #aj cc4 am\nts to -#j4jb cc41 or -#j4jjb = ea* cubic c5timet] 7,note #c74 ,9 ! calculation ( corrections ! temp]ature ( ! wat] mu/ be tak5 into acc\nt1 if ?is v>ies m ?an #d;,c4 f ! laboratory /&>d temp]ature1 consult+ ! table ( d5sities ( wat] 9 ! ,app5dix4 ,f ! f9al data1 plot ! corrections to be appli$ s t !y may be easily read = ea* cubic c5timet] ?r\gh\t ! burette4 ,! total correction at ea* #aj cc4 may also be writt5 on ! burette ) a diamond1 or et*+ ink1 = p]man5ce ( record4 ,note #a3 ,a small quantity ( liquid at fir/ adh]es to ! side ( ev5 a clean burette4 ,?is sl[ly unites ) ! ma9 body ( liquid1 b requires an appreciable "t4 ,?ree m9utes is a suffici5t int]val1 b n too long1 & %\ld be adopt$ 9 e in/ance ?r\gh\t ! :ole volumetric practice be=e f9al read+s are record$4 ,note #b3 ,a comp>atively r\gh balance1 capable ( weigh+ to c5tigrams1 is suffici5tly accurate = use 9 calibrations1 = a mom5t's reflection w %[ t x w\ld be useless to weigh ! wat] ) an accuracy great] ?an t ( ! read+s tak5 on ! burette4 ,! latt] _c exce$ #j4ja cc4 9 accuracy1 :i* corresponds to #j4ja gram4 ,! /ud5t %\ld cle>ly und]/& t 6all o!r weigh+s61 except ^? = calibration1 %\ld be made accurately to #j4jjja gram1 unless special directions are giv5 to ! contr>y4 ,corrections = temp]ature v>iations ( less ?an #d;,c4 are negligible1 z !y am\nt to less ?an #j4ja gram = ea* #aj grams ( wat] )drawn4 ,note #c3 ,%\ld ! error discov]$ 9 any int]val ( #aj cc4 on ! burette exce$ #j4aj cc41 x is advisable to weigh small portions 7ev5 #a cc47 to locate ! position ( ! v>iation ( bore 9 ! tube r ?an to di/ribute ! correction uni=mly ov] ! correspond+ #aj cc4 ,! latt] is ! usual c\rse = small corrections1 & x is conv5i5t to calculate ! correction correspond+ to ea* cubic c5timet] & to record x 9 ! =m ( a table or calibration c>d1 or to plot a curve repres5t+ ! values4 ,burettes may also be calibrat$ by draw+ (f ! liquid 9 successive portions ?r\gh a #e cc4 pipette :i* has be5 accurately calibrat$1 z a sub/itute = weigh+4 ,if _m burettes are to be te/$1 ?is is a m rapid me?od4 ,,pipettes ,a 6pipette6 may consi/ ( a n>r[ tube1 9 ! middle ( :i* is bl[n a bulb ( a capacity a little less ?an t :i* x is desir$ to measure by ! pipette2 or x may be a m9iature burette1 )\t ! /opcock or rubb] tip at ! l[] extremity4 ,9 ei!r case1 ! fl[ ( liquid is regulat$ by ! pressure ( ! f+] on ! top1 :i* gov]ns ! admission ( ! air4 ,pipettes are usually already graduat$ :5 pur*as$1 b !y require calibration = accurate "w4 ,,calibration ,,( ,,pipettes ,,proc$ure4--,clean ! pipette4 ,draw di/ill$ wat] into x by suck+ at ! upp] end until ! wat] is well above ! graduation m>k4 ,quickly place ! =ef+] ov] ! top ( ! tube1 ?us prev5t+ ! entrance ( air & hold+ ! wat] 9 ! pipette4 ,cauti\sly admit a little air by releas+ ! pressure ( ! f+]1 & all[ ! level ( ! wat] to fall until ! l[e/ po9t ( ! m5iscus is level ) ! graduation4 ,hold ! wat] at t po9t by pressure ( ! f+] & !n all[ ! wat] to run out f ! pipette into a small t>$1 or weigh$1 beak] or flask4 ,aft] a def9ite "t int]val1 usually two to ?ree m9utes1 t\* ! end ( ! pipette aga9/ ! side ( ! beak] or flask to remove any liquid adh]+ to x 7,note #a74 ,! increase 9 weight ( ! flask 9 grams repres5ts ! volume ( ! wat] 9 cubic c5timet]s deliv]$ by ! pipette4 ,calculate ! necess>y correction4 ,note #a3 ,a def9ite int]val mu/ be all[$ = dra9+1 & a def9ite practice adopt$ ) respect to ! removal ( ! liquid :i* collects at ! end ( ! tube1 if ! pipette is design$ to deliv] a specific volume :5 empti$4 ,?is liquid may be remov$ at ! end ( a def9ite int]val ei!r by t\*+ ! side ( ! vessel or by g5tly bl[+ out ! la/ drops4 ,ei!r practice1 :5 adopt$1 mu/ be uni=mly adh]$ to4 ,,flasks 6,graduat$ or measur+ flasks6 are simil> to ! ord9>y flat-bottom$ flasks1 b are provid$ ) long1 n>r[ necks 9 ord] t slight v>iations 9 ! position ( ! m5iscus ) respect to ! graduation %all repres5t a m9imum volume ( liquid4 ,! flasks mu/ be ( su* a capacity t1 :5 fill$ ) ! specifi$ volume1 ! liquid rises well into ! neck4 ,,graduation ,,( ,,flasks ,x is a g5]al cu/om to pur*ase ! flasks ungraduat$ & to graduate !m = use "u /&>d conditions select$ = ! laboratory 9 "q4 ,!y may be graduat$ = cont5ts or deliv]y4 ,:5 graduat$ = cont5ts !y conta9 a specifi$ volume :5 fill$ to ! graduation at a specifi$ temp]ature1 & require to be wa%$ out 9 ord] to remove all ( ! solution f ! flask4 ,flasks graduat$ = deliv]y w deliv] ! specifi$ volume ( a liquid )\t r9s+4 ,a flask may1 ( c\rse1 be graduat$ = bo? cont5ts & deliv]y by plac+ two graduation m>ks ^u x4 ,,proc$ure4--,to calibrate a flask = 6cont5ts61 proce$ z foll[s3 ,clean ! flask1 us+ a *romic acid solution1 & dry x c>efully outside & inside4 ,t>e x accurately2 p\r wat] into ! flask until ! weight ( ! latt] c\nt]balances weights on ! opposite pan :i* equal 9 grams ! numb] ( cubic c5timet]s ( wat] :i* ! flask is to conta94 ,remove any excess ( wat] ) ! aid ( filt] pap] 7,note #a74 ,take ! flask f ! balance1 /opp] x1 place x 9 a ba? at ! desir$ temp]ature1 usually #ae4e or #ag4e;,c41 & aft] an h\r m>k on ! neck ) a diamond ! location ( ! l[e/ po9t ( ! m5iscus 7,note #b74 ,! m>k may be et*$ ^u ! flask by hydr(luoric acid1 or by ! use ( an et*+ ink n[ commonly sold on ! m>ket4 ,to graduate a flask :i* is design$ to 6deliv]6 a specifi$ volume1 proce$ z foll[s3 ,clean ! flask z usual & wipe all moi/ure f ! outside4 ,fill x ) di/ill$ wat]4 ,p\r out ! wat] & all[ ! wat] to dra9 f ! flask = ?ree m9utes4 ,c\nt]balance ! flask ) weights to ! ne>e/ c5tigram4 ,add weights correspond+ 9 grams to ! volume desir$1 & add di/ill$ wat] to c\nt]balance ^! weights4 ,an excess ( wat]1 or wat] adh]+ to ! neck ( ! flask1 may be remov$ by means ( a /rip ( clean filt] pap]4 ,/opp] ! flask1 place x 9 a ba? at #ae4e;,c4 or #ag4e;,c4 &1 aft] an h\r1 m>k ! location ( ! l[e/ po9t ( ! m5iscus1 z describ$ above4 ,note #a3 ,! all[able error 9 c\nt]balanc+ ! wat] & weights v>ies ) ! volume ( ! flask4 ,x %\ld n exce$ "o t5-?\s&? ( ! weight ( wat]4 ,note #b3 ,o!r me?ods are employ$ :i* involve ! use ( calibrat$ app>atus f :i* ! desir$ volume ( wat] may be run into ! dry flask & ! position ( ! m5iscus m>k$ directly ^u x4 ,= a description ( a proc$ure :i* is mo/ conv5i5t :5 _m flasks are to be calibrat$1 ! /ud5t is ref]r$ to ! 6,am4 ,*em ,j461 #af1 #dgi4 ,,g5]al ,,directions ,,= ,,volumetric ,,analyses ,x _c be too /rongly emphasiz$ t = ! success ( analyses uni=mity ( practice mu/ prevail ?r\gh\t all volumetric "w ) respect to ^? factors :i* c influ5ce ! accuracy ( ! measurem5t ( liquids4 ,= example1 :atev] conditions are impos$ dur+ ! calibration ( a burette1 pipette1 or flask 7notably ! "t all[$ = dra9+71 mu/ also prevail :5ev] ! flask or burette is us$4 ,! /ud5t %\ld also be con/antly wat*ful to insure p>allel conditions dur+ bo? /&>dization & analy/ ) respect to ! f9al volume ( liquid 9 :i* a titration takes place4 ,! value ( a /&>d solution is only accurate "u ! conditions :i* prevail$ :5 x 0 /&>diz$4 ,x is pla9 t ! /&>d solutions mu/ be scrupul\sly protect$ f conc5tration or dilution1 aft] _! value has be5 e/abli%$4 ,accord+ly1 great c>e mu/ be tak5 to ?or\ghly r9se out all burettes1 flasks1 etc41 ) ! solutions :i* !y are to conta91 9 ord] to remove all traces ( wat] or o!r liquid :i* c\ld act z a dilu5t4 ,x is be/ to wa% out a burette at lea/ ?ree times ) small portions ( a solution1 all[+ ea* to run out ?r\gh ! tip be=e assum+ t ! burette is 9 a condition to be fill$ & us$4 ,x is1 ( c\rse1 possible to dry measur+ in/rum5ts 9 a hot closet1 b ?is is t$i\s & unnecess>y4 ,to ! same end1 all solutions %\ld be kept /opp]$ & away f direct sunlight or heat4 ,! bottles %\ld be %ak5 be=e use to collect any liquid :i* may h di/ill$ f ! solution & cond5s$ on ! sides4 ,! /ud5t is aga9 rem9d$ t v>iations 9 temp]ature ( volumetric solutions mu/ be c>efully not$1 & c>e %\ld always be tak5 t no s\rce ( heat is suffici5tly ne> ! solutions to raise ! temp]ature dur+ use4 ,mu* "t may be sav$ by e/imat+ ! approximate volume ( a /&>d solution :i* w be requir$ = a titration 7if ! data are obta9able7 be=e beg9n+ ! op]ation4 ,x is !n possible to run 9 rapidly approximately ! requir$ am\nt1 aft] :i* x is only necess>y to det]m9e ! end-po9t sl[ly & ) accuracy4 ,9 su* cases1 h[ev]1 ! k ( ! approximate am\nt to be requir$ %\ld nev] be all[$ to influ5ce ! judgm5t reg>d+ ! actual end-po9t4 ,,/&>d ,,solutions ,! /r5g? or value ( a solution = a specific reaction is det]m9$ by a proc$ure call$ 6,/&>dization61 9 :i* ! solution is br\ght into reaction ) a def9ite weight ( a sub/ance ( kn[n purity4 ,= example1 a def9ite weight ( pure sodium c>bonate may be dissolv$ 9 wat]1 & ! volume ( a solution ( hydro*loric acid necess>y to exactly neutralize ! c>bonate accurately det]m9$4 ,f ^! data ! /r5g? or value ( ! acid is kn[n4 ,x is !n a 6/&>d solution64 ,,normal ,,solutions ,/&>d solutions may be made ( a purely empirical /r5g? dictat$ solely by conv5i5ce ( manipulation1 or ! conc5tration may be *os5 ) ref]5ce to a sy/em :i* is applicable to all solutions1 & bas$ ^u *emical equival5ts4 ,su* solutions are call$ 6,normal ,solutions6 & conta9 su* an am\nt ( ! react+ sub/ance p] lit] z is equival5t 9 its *emical action to "o gram ( hydrog51 or eight grams ( oxyg54 ,solutions conta9+ "o half1 "o t5?1 or "o "o-hundr$? ( ?is quantity p] lit] are call$1 respectively1 half-normal1 t5?-normal1 or hundr$?-normal solutions4 ,s9ce normal solutions ( v>i\s reag5ts are all ref]r$ to a common /&>d1 !y h an advantage n possess$ by empirical solutions1 namely1 t !y are exactly equival5t to ea* o!r4 ,?us1 a lit] ( a normal solution ( an acid w exactly neutralize a lit] ( a normal alkali solution1 & a lit] ( a normal oxidiz+ solution w exactly react ) a lit] ( a normal r$uc+ solution1 & s on4 ,beside ! advantage ( uni=mity1 ! use ( normal solutions simplifies ! calculations ( ! results ( analyses4 ,?is is p>ticul>ly true if1 9 connection ) ! normal solution1 ! weight ( sub/ance = analysis is *os5 ) ref]5ce to ! atomic or molecul> weight ( ! con/itu5t to be det]m9$4 7,see problem #bf47 ,! prep>ation ( an 6exactly6 normal1 half-normal1 or t5?-normal solution requires consid]able "t & c>e4 ,x is usually c>ri$ out only :5 a l>ge numb] ( analyses are to be made1 or :5 ! analy/ has "s o!r specific purpose 9 view4 ,x is1 h[ev]1 a comp>atively easy matt] to prep>e /&>d solutions :i* diff] b slightly f ! normal or half-normal solution1 & ^! h ! advantage ( practical equality2 t is1 two approximately half-normal solutions are m conv5i5t to "w ) ?an two :i* are widely diff]5t 9 /r5g?4 ,x is1 h[ev]1 true t "s ( ! advantage :i* p]ta9s to ! use ( normal solutions z reg>ds simplicity ( calculations is lo/ :5 us+ ^! approximate solutions4 ,! application ( ^! g5]al /atem5ts w be made cle> 9 connection ) ! use ( normal solutions 9 ! v>i\s types ( volumetric processes :i* foll[4 ,i4 ,,neutralization ,,me?ods ,,alkalimetry ,,& ,,acidimetry ,,g5]al ,,discussion 6,/&>d ,acid ,solutions6 may be prep>$ f ei!r hydro*loric1 sulphuric1 or oxalic acid4 ,hydro*loric acid has ! advantage ( =m+ soluble comp\nds ) ! alkal9e e>?s1 b its solutions _c be boil$ )\t dang] ( loss ( /r5g?2 sulphuric acid solutions may be boil$ )\t loss1 b ! acid =ms insoluble sulphates ) ?ree ( ! alkal9e e>?s2 oxalic acid c be accurately weigh$ = ! prep>ation ( solutions1 & its solutions may be boil$ )\t loss1 b x =ms insoluble oxalates ) ?ree ( ! alkal9e e>?s & _c be us$ ) c]ta9 ( ! indicators4 6,/&>d ,alkali ,solutions6 may be prep>$ f sodium or potassium hydroxide1 sodium c>bonate1 b>ium hydroxide1 or ammonia4 ,( sodium & potassium hydroxide1 x may be said t !y c be us$ ) all indicators1 & _! solutions may be boil$1 b !y absorb c>bon dioxide readily & attack ! glass ( bottles1 !reby los+ /r5g?2 sodium c>bonate may be weigh$ directly if its purity is assur$1 b ! pres5ce ( c>bonic acid f ! c>bonate is a disadvantage ) _m indicators2 b>ium hydroxide solutions may be prep>$ :i* are entirely free f c>bon dioxide1 & su* solutions imm$iately %[ by precipitation any contam9ation f absorption1 b ! hydroxide is n freely soluble 9 wat]2 ammonia does n absorb c>bon dioxide z readily z ! cau/ic alkalies1 b its solutions _c be boil$ nor c !y be us$ ) all indicators4 ,! *oice ( a solution mu/ dep5d ^u ! nature ( ! "w 9 h&4 ,a 6normal acid solution6 %\ld conta9 9 "o lit] t quantity ( ! reag5t :i* repres5ts #a gram ( hydrog5 replaceable by a base4 ,= example1 ! normal solution ( hydro*loric acid 7,h,cl7 %\ld conta9 #cf4df grams ( gase\s hydrog5 *loride1 s9ce t am\nt furni%es ! requisite #a gram ( replaceable hydrog54 ,on ! o!r h&1 ! normal solution ( sulphuric acid 7,h#b,,s#d7 %\ld conta9 only #di4jc grams1 i4e41 "o half ( its molecul> weight 9 grams4 ,a 6normal alkali solution6 %\ld conta9 suffici5t alkali 9 a lit] to replace #a gram ( hydrog5 9 an acid4 ,?is quantity is repres5t$ by ! molecul> weight 9 grams 7#dj4ja7 ( sodium hydroxide 7,na,o,h71 :ile a sodium c>bonate solution 7,na#b;,,co#c7 %\ld conta9 b "o half ! molecul> weight 9 grams 7i4e41 #ec4j grams7 9 a lit] ( normal solution4 ,half-normal or t5?-normal solutions are employ$ 9 mo/ analyses 7except 9 ! case ( ! less soluble b>ium hydroxide74 ,solutions ( ! latt] /r5g? yield m accurate results :5 small p]c5tages ( acid or alkali are to be det]m9$4 ,,indicators ,x has already be5 po9t$ out t ! purpose ( an indicator is to m>k 7usually by a *ange ( color7 ! po9t at :i* j en\gh ( ! titrat+ solution has be5 add$ to complete ! *emical *ange :i* x is int5d$ to br+ ab\t4 ,9 ! neutralization processes :i* are employ$ 9 ! measurem5t ( alkalies 76alkalimetry67 or acids 76acidimetry67 ! end-po9t ( ! reaction %\ld1 9 pr9ciple1 be t ( complete neutrality4 ,express$ 9 t]ms ( ionic reactions1 x %\ld be ! po9t at :i* ! ,h ions f an acid,note #a unite ) a correspond+ numb] ( ,,oh- ions f a base to =m wat] molecules1 z 9 ! equation ,h1 ,cl- ,na1 ,,oh- -- ,na1 ,cl- 7,h#b,o74 ,x is n usually possible to realize ?is condition ( exact neutrality1 b x is possible to approa* x ) suffici5t exactness = analytical purposes1 s9ce sub/ances are kn[n :i*1 9 solution1 und]go a %>p *ange ( color z soon z ev5 a m9ute excess ( ,h or ,,oh- ions are pres5t4 ,"s1 z w be se51 react %>ply 9 ! pres5ce ( ,h ions1 & o!rs ) ,,oh- ions4 ,^! sub/ances employ$ z indicators are usually organic comp\nds ( complex /ructure & are closely alli$ to ! dye/uffs 9 "*4 ,note #a3 ,a k on ! "p ( ! /ud5t ( ! ionic !ory z appli$ to aque\s solutions ( electrolytes is assum$4 ,a brief outl9e ( ! m important applications ( ! !ory is giv5 9 ! ,app5dix4 ,,behavior ,,( ,,organic ,,indicators ,! indicators 9 mo/ common use = acid & alkali titrations are me?yl orange1 litmus1 & ph5olph?ale94 ,9 ! foll[+ discussion ( ! pr9ciples und]ly+ ! behavior ( ! indicators z a class1 me?yl orange & ph5olph?ale9 w be tak5 z types4 ,x has j be5 po9t$ out t indicators are bodies ( complicat$ /ructure4 ,9 ! case ( ! two indicators nam$1 ! *anges :i* !y und]go h be5 c>efully /udi$ by ,/ieglitz 76,j4 ,am4 ,*em4 ,soc461 #be1 #aaab7 & o!rs1 & x appe>s t ! *anges involv$ are ( two sorts3 ,fir/1 a re>rangem5t ( ! atoms )9 ! molecule1 su* z (t5 occurs 9 organic comp\nds2 &1 second1 ionic *anges4 ,! int]molecul> *anges _c appropriately be discuss$ "h1 z !y involve a some:at detail$ k ( ! classification & g5]al behavior ( organic comp\nds2 !y w1 !re=e1 be m]ely allud$ to1 & only ! ionic *anges foll[$4 ,me?yl orange is a repres5tative ( ! gr\p ( indicators :i*1 9 aque\s solutions1 behave z weak bases4 ,! yell[ color :i* x imp>ts to solutions is ascrib$ to ! pres5ce ( ! undissociat$ base4 ,if an acid1 su* z ,h,cl1 is add$ to su* a solution1 ! acid reacts ) ! indicator 7neutralizes x7 & a salt is =m$1 z indicat$ by ! equation3 7,m4o471 ,,oh- ,h1 ,cl- -- 7,m4o47 ,cl- 7,h#b,o74 ,?is salt ionizes into 7,m4o47 7us+ ?is abbreviation = ! positive complex7 & ,cl-2 b simultane\sly ) ?is ionization !re appe>s to be an int]nal re>rangem5t ( ! atoms :i* results 9 ! production ( a cation :i* may be designat$ z 7,m'4o'471 & x is ?is :i* imp>ts a *>act]i/ic r$ color to ! solution4 ,z ^! *anges occur 9 ! pres5ce ( ev5 a v small excess ( acid 7t is1 ( ,h ions71 x s]ves z ! desir$ index ( _! pres5ce 9 ! solution4 ,if1 n[1 an alkali1 su* z ,na,o,h1 is add$ to ?is r$d5$ solution1 ! rev]se s]ies ( *anges takes place4 ,z soon z ! free acid pres5t is neutraliz$1 ! slighte/ excess ( sodium hydroxide1 act+ z a /rong base1 sets free ! weak1 little-dissociat$ base ( ! indicator1 & at ! mom5t ( its =mation x rev]ts1 because ( ! re>rangem5t ( ! atoms1 to ! yell[ =m3 ,,oh- 7,m'4o'47 -- ,m'4o'4,,oh -- ,m4o4,,oh4 ,ph5olph?ale91 on ! o!r h&1 is a v weak1 little-dissociat$ acid1 :i* is colorless 9 neutral aque\s solution or 9 ! pres5ce ( free ,h ions4 ,:5 an alkali is add$ to su* a solution1 ev5 9 slight excess1 ! anion ( ! salt :i* has =m$ f ! acid ( ! indicator und]goes a re>rangem5t ( ! atoms1 & a new ion1 7,ph'71 is =m$1 :i* imp>ts a p9k color to ! solution3 ,h1 7,ph7- ,na1 ,,oh- -- 7,h#b,o7 ,na1 7,ph7- -- ,na1 7,ph'7- ,! addition ( ! slighte/ excess ( an acid to ?is solution1 on ! o!r h&1 occasions fir/ ! rev]sion to ! colorless ion & !n ! sett+ free ( ! undissociat$ acid ( ! indicator3 ,h1 7,ph'7- -- ,h1 7,ph7- -- 7,h,ph74 ,( ! common indicators me?yl orange is ! mo/ s5sitive t[>d alkalies & ph5olph?ale9 t[>d acids2 ! o!rs occupy int]m$iate positions4 ,t me?yl orange %\ld be mo/ s5sitive t[>d alkalies is evid5t f ! foll[+ consid]ations3 ,me?yl orange is a weak base &1 !re=e1 b little dissociat$4 ,x %\ld1 !n1 be =m$ 9 ! undissociat$ condition z soon z ev5 a slight excess ( ,,oh- ions is pres5t 9 ! solution1 & !re %\ld be a prompt *ange f r$ to yell[ z outl9$ above4 ,on ! o!r h&1 x %\ld be an unsatisfactory indicator = use ) weak acids 7acetic acid1 = example7 because ! salts :i* x =ms ) su* acids are1 l all salts ( t type1 hydrolyz$ to a consid]able ext5t4 ,?is hydrolytic *ange is illu/rat$ by ! equation3 7,m4o47 ,c#b;,h#c,o#b- ,h1 ,,oh- -- ,m4o4,,oh ,h1 ,c#b;,h#c,o#b-4 ,comp>ison ( ?is equation ) t on page #cj w make x pla9 t hydrolysis is j ! rev]se ( neutralization & mu/1 accord+ly1 int]f]e ) x4 ,salts ( me?yl orange ) weak acids are s f> hydrolyz$ t ! end-po9t is unc]ta91 & me?yl orange _c be us$ 9 ! titration ( su* acids1 :ile ) ! v weak acids1 su* z c>bonic acid or hydrog5 sulphide 7hydrosulphuric acid71 ! salts =m$ ) me?yl orange are1 9 effect1 completely hydrolyz$ 7i4e41 no neutralization occurs71 & me?yl orange is accord+ly sc>cely affect$ by ^! acids4 ,?is expla9s its usefulness1 z ref]r$ to lat]1 = ! titration ( /rong acids1 su* z hydro*loric acid1 ev5 9 ! pres5ce ( c>bonates or sulphides 9 solution4 ,ph5olph?ale91 on ! o!r h&1 %\ld be1 z x is1 ! be/ ( ! common indicators = use ) weak acids4 ,=1 s9ce x is itself a weak acid1 x is v little dissociat$1 & its ne>ly undissociat$1 colorless molecules are promptly =m$ z soon z !re is any free acid 7t is1 free ,h ions7 9 ! solution4 ,?is indicator _c1 h[ev]1 be successfully us$ ) weak bases1 ev5 ammonium hydroxide2 =1 s9ce x is weak acid1 ! salts :i* x =ms ) weak alkalies are easily hydrolyz$1 & z a consequ5ce ( ?is hydrolysis ! *ange ( color is n %>p4 ,?is indicator c1 h[ev]1 be successfully us$ ) /rong bases1 because ! salts :i* x =ms ) su* bases are mu* less hydrolyz$ & because ! excess ( ,,oh- ions f ^! bases also dim9i%es ! hydrolytic action ( wat]4 ,?is indicator is affect$ by ev5 s weak an acid z c>bonic acid1 :i* mu/ be remov$ by boil+ ! solution be=e titration4 ,x is ! indicator mo/ g5]ally employ$ = ! titration ( organic acids4 ,9 g5]al1 x may be /at$ t :5 a /rong acid1 su* z hydro*loric1 sulphuric or nitric acid1 is titrat$ aga9/ a /rong base1 su* z sodium hydroxide1 potassium hydroxide1 or b>ium hydroxide1 any ( ^! indicators may be us$1 s9ce v little hydrolysis ensues4 ,x has be5 not$ above t ! color *ange does n occur exactly at !oretical neutrality1 f :i* x foll[s t no two indicators w %[ exactly ! same end-po9t :5 acids & alkalis are br\ght toge!r4 ,x is pla91 !re=e1 t ! same indicator mu/ be employ$ = bo? /&>dization & analysis1 & t1 if ?is is done1 accurate results are obta9able4 ,! foll[+ table 7,note #a7 illu/rates ! v>iations 9 ! volume ( an alkali solution 7t5?-normal sodium hydroxide7 requir$ to produce an alkal9e end-po9t :5 run into #aj cc4 ( t5?-normal sulphuric acid1 dilut$ ) #ej cc4 ( wat]1 us+ five drops ( ea* ( ! diff]5t indicator solutions4 ,,indicator ,n_/#aj ,n_/#aj ,,color ,,9 ,,acid,,color ,,9 ,,alka- ,h#b,,s#d ,na,o,h ,,solution ,,l9e ,,solution cc4 cc4 cc4 ,me?yl orange #aj #i4ij ,r$ ,yell[ ,lacmoid #aj #aj4jj ,r$ ,blue ,litmus #aj #aj4jj ,r$ ,blue ,rosalic acid #aj #aj4jg ,yell[ ,p9k ,ph5olph?ale9 #aj #aj4aj ,colorless ,p9k ,x %\ld also be /at$ t !re are occasionally second>y *anges1 o!r ?an ^? outl9$ above1 :i* dep5d ^u ! temp]ature & conc5tration ( ! solutions 9 :i* ! indicators are us$4 ,^! *anges may influ5ce ! s5sitiv5ess ( an indicator4 ,x is important1 !re=e1 to take pa9s to use approximately ! same volume ( solution :5 /&>diz+ t is likely to be employ$ 9 analysis2 & :5 x is necess>y1 z is (t5 ! case1 to titrate ! solution at boil+ temp]ature1 ! /&>dization %\ld take place "u ! same conditions4 ,x is also obvi\s t s9ce "s acid or alkali is requir$ to react ) ! indicator itself1 ! am\nt ( indicator us$ %\ld be uni=m & n excessive4 ,usually a few drops ( solution w suffice4 ,! =ego+ /atem5ts ) respect to ! behavior ( indicators pres5t ! subject 9 its simple/ t]ms4 ,_m sub/ances o!r ?an ^? nam$ may be employ$1 & !y h be5 c>efully /udi$ to det]m9e ! exact conc5tration ( ,h ions at :i* ! color *ange ( ea* occurs4 ,x is ?us possible to select an indicator = a p>ticul> purpose ) consid]able accuracy4 ,z data ( ?is nature d n belong 9 an introductory manual1 ref]5ce is made to ! foll[+ pap]s or books 9 :i* a m ext5d$ treatm5t ( ! subject may be f\nd3 ,wa%burn1 ,e4,w41 ,pr9ciples ( ,physical ,*emi/ry 7,mc,graw-,hill ,book ,co471 7,second ,edition1 #aiba71 pp4 #chj-chg4 ,prideaux1 ,e4,b4,r41 ,! ,!ory & ,use ( ,indicators 7,con/able ,co41 ,ltd471 7#aiag74 ,salm1 ,e41 ,a ,/udy ( ,indicators1 6,z4 physik4 ,*em461 #eg 7#aijf71 #dga-eja4 ,/ieglitz1 ,j41 ,!ories ( ,indicators1 6,j4 ,am4 ,*em4 ,soc461 #be 7#aijc71 #aaab-aabg4 ,noyes1 ,a4,a41 ,quantitative ,applications ( ! ,!ory ( ,indicators to ,volumetric ,analysis1 6,j4 ,am4 ,*em4 ,soc461 #cb 7#aiaa71 #hae-hfa4 ,bj]rum1 ,n41 ,g5]al ,discussion1 6,z4 ,anal4 ,*em461 #ff 7#aiag71 #ac-bh & #ha-ie4 ,o/wald1 ,w41 ,colloid ,*emi/ry ( ,indicators1 6,z4 ,*em4 ,ind4 ,kolloide61 #aj 7#aiab71 #acb-adf4 ,note #a3 ,glas]1 6,indikator5 d] ,acidimetrie und ,alkalimetrie64 ,wiesbad51 #aija4 ,,prep>ation ,,( ,,indicator ,,solutions ,a 6me?yl orange solution6 = use z an indicator is commonly made by dissolv+ #j4je-j4a gram ( ! comp\nd 7also kn[n z ,orange ,,iii7 9 a few cubic c5timet]s ( alcohol & dilut+ ) wat] to #ajj cc4 ,a good grade ( mat]ial %\ld be secur$4 ,x c be successfully us$ = ! titration ( hydro*loric1 nitric1 sulphuric1 phosphoric1 & sulphur\s acids1 & is p>ticul>ly useful 9 ! det]m9ation ( bases1 su* z sodium1 potassium1 b>ium1 calcium1 & ammonium hydroxides1 & ev5 _m ( ! weak organic bases4 ,x c also be us$ = ! det]m9ation1 by titration ) a /&>d solution ( a /rong acid1 ( ! salts ( v weak acids1 su* z c>bonates1 sulphides1 ars5ites1 borates1 & silicates1 because ! weak acids :i* are lib]at$ d n affect ! indicator1 & ! r$d5+ ( ! solution does n take place until an excess ( ! /rong acid is add$4 ,x %\ld be us$ 9 cold1 n too dilute1 solutions4 ,its s5sitiv5ess is less5$ 9 ! pres5ce ( consid]able quantities ( ! salts ( ! alkalies4 ,a 6ph5olph?ale9 solution6 is prep>$ by dissolv+ #a gram ( ! pure comp\nd 9 #ajj cc4 ( #ie p] c5t alcohol4 ,?is indicator is p>ticul>ly valuable 9 ! det]m9ation ( weak acids1 especially organic acids4 ,x _c be us$ ) weak bases1 ev5 ammonia4 ,x is affect$ by c>bonic acid1 :i* mu/1 !re=e1 be remov$ by boil+ :5 o!r acids are to be measur$4 ,x c be us$ 9 hot solutions4 ,"s c>e is necess>y to keep ! volume ( ! solutions to be titrat$ approximately uni=m 9 /&>dization & 9 analysis1 & ?is volume %\ld n 9 g5]al exce$ #abe-aej cc4 = ! be/ results1 s9ce ! comp\nds =m$ by ! indicator und]go *anges 9 v dilute solution :i* less5 its s5sitiv5ess4 ,! prep>ation ( a 6solution ( litmus6 :i* is suitable = use z an indicator involves ! sep>ation f ! comm]cial litmus ( azoli?m9e1 ! true color+ pr9ciple4 ,soluble litmus tablets are (t5 obta9able1 b ! litmus z commonly suppli$ to ! m>ket is mix$ ) calcium c>bonate or sulphate & compress$ into lumps4 ,to prep>e a solution1 ^! are p[d]$ & treat$ two or ?ree times ) alcohol1 :i* dissolves out c]ta9 con/itu5ts :i* cause a tr\blesome int]m$iate color if n remov$4 ,! alcohol is decant$ & dra9$ (f1 aft] :i* ! litmus is extract$ ) hot wat] until exhau/$4 ,! solution is all[$ to settle = "s "t1 ! cle> liquid siphon$ (f1 conc5trat$ to "o-?ird its volume & acetic acid add$ 9 slight excess4 ,x is !n conc5trat$ to a sirup1 & a l>ge excess ( #ie p] c5t4 alcohol add$ to x4 ,?is precipitates ! blue color+ matt]1 :i* is filt]$ (f1 wa%$ ) alcohol1 & f9ally dissolv$ 9 a small volume ( wat] & dilut$ until ab\t ?ree drops ( ! solution add$ to #ej cc4 ( wat] j produce a di/9ct color4 ,?is solution mu/ be kept 9 an un/opp]$ bottle4 ,x %\ld be protect$ f du/ by a loose plug ( absorb5t cotton4 ,if kept 9 a clos$ bottle x soon und]goes a r$uction & loses its color1 :i*1 h[ev]1 is (t5 re/or$ by exposure to ! air4 ,litmus c be employ$ successfully ) ! /rong acids & bases1 & also ) ammonium hydroxide1 al?\gh ! salts ( ! latt] influ5ce ! indicator unfavorably if pres5t 9 consid]able conc5tration4 ,x may be employ$ ) "s ( ! /rong] organic acids1 b ! use ( ph5olph?ale9 is to be pref]r$4 ,,prep>ation ,,( ,,/&>d ,,solutions 6,hydro*loric ,acid & ,sodium ,hydroxide4 ,approximate ,/r5g?61 #j4e ,n ,,proc$ure4--,measure out #dj cc4 ( conc5trat$1 pure hydro*loric acid into a clean lit] bottle1 & dilute ) di/ill$ wat] to an approximate volume ( #ajjj cc4 ,%ake ! solution vigor\sly = a full m9ute to insure uni=mity4 ,be sure t ! bottle is n too full to p]mit ( a ?or\gh mix+1 s9ce lack ( c>e at ?is po9t w be ! cause ( mu* wa/$ "t 7,note #a74 ,weigh out1 ^u a r\gh balance1 #bc grams ( sodium hydroxide 7,note #b74 ,dissolve ! hydroxide 9 wat] 9 a beak]4 ,p\r ! solution into a lit] bottle & dilute1 z above1 to approximately #ajjj cc4 ,?is bottle %\ld pref]ably h a rubb] /opp]1 z ! hydroxide solution attacks ! glass ( ! gr\nd jo9t ( a glass /opp]1 & may cem5t ! /opp] to ! bottle4 ,%ake ! solution z describ$ above4 ,note #a3 ,! orig9al solutions are prep>$ ( a /r5g? great] ?an #j4e ,n1 z !y are m readily dilut$ ?an /r5g!n$ if lat] adju/m5t is desir$4 ,too mu* c>e _c be tak5 to insure p]fect uni=mity ( solutions be=e /&>dization1 & ?or\ghness 9 ?is respect w1 z /at$1 (t5 avoid mu* wa/e ( "t4 ,a solution once ?or\ghly mix$ rema9s uni=m4 ,note #b3 ,comm]cial sodium hydroxide is usually impure & always conta9s m or less c>bonate2 an all[ance is !re=e made = ?is impurity by plac+ ! weight tak5 at #bc grams p] lit]4 ,if ! hydroxide is kn[n to be pure1 a less] am\nt 7say #ba grams7 w suffice4 ,,comp>ison ,,( ,,acid ,,& ,,alkali ,,solutions ,,proc$ure4--,r9se a previ\sly calibrat$ burette ?ree times ) ! hydro*loric acid solution1 us+ #aj cc4 ea* "t1 & all[+ ! liquid to run out ?r\gh ! tip to displace all wat] & air f t "p ( ! burette4 ,!n fill ! burette ) ! acid solution4 ,c>ry out ! same proc$ure ) a second burette1 us+ ! sodium hydroxide solution4 ,! acid solution may be plac$ 9 a pla9 or 9 a glass-/opp]$ burette z may be m conv5i5t1 b ! alkal9e solution %\ld nev] be all[$ to rema9 long 9 a glass-/opp]$ burette1 z x t5ds to cem5t ! /opp] to ! burette1 r5d]+ x useless4 ,x is pref]able to use a pla9 burette = ?is solution4 ,:5 ! burettes are ready = use & all air bubbles displac$ f ! tip 7see ,note #b1 page #ag7 note ! exact position ( ! liquid 9 ea*1 & record ! read+s 9 ! notebook4 7,consult page #ahh47 ,run out f ! burette into a beak] ab\t #dj cc4 ( ! acid & add two drops ( a solution ( me?yl orange2 dilute ! acid to ab\t #hj cc4 & run out alkali solution f ! o!r burette1 /irr+ con/antly1 until ! p9k has giv5 place to a yell[4 ,wa% d[n ! sides ( ! beak] ) a little di/ill$ wat] if ! solution has spatt]$ ^u !m1 return ! beak] to ! acid burette1 & add acid to re/ore ! p9k2 cont9ue ^! alt]nations until ! po9t is accurately fix$ at :i* a s+le drop ( ei!r solutions s]v$ to produce a di/9ct *ange ( color4 ,select z ! f9al end-po9t ! appe>ance ( ! fa9te/ p9k t+e :i* c be recogniz$1 or ! disappe>ance ( ?is t+e1 leav+ a pure yell[2 b always titrate to ! same po9t 7,note #a74 ,if ! titration has occupi$ m ?an ! ?ree m9utes requir$ = dra9+ ! sides ( ! burette1 ! f9al read+ may be tak5 imm$iately & record$ 9 ! notebook4 ,refill ! burettes & repeat ! titration4 ,f ! records ( calibration already obta9$1 correct ! burette read+s & make corrections = temp]ature1 if necess>y4 ,obta9 ! ratio ( ! sodium hydroxide solution to t ( hydro*loric acid by divid+ ! numb] ( cubic c5timet]s ( acid us$ by ! numb] ( cubic c5timet]s ( alkali requir$ = neutralization4 ,! *eck results ( ! two titrations %\ld n v>y by m ?an two p>ts 9 "o ?\s& 7,note #b74 ,if ! v>iation 9 results is great] ?an ?is1 refill ! burettes & repeat ! titration until satisfactory values are obta9$4 ,use a new page 9 ! notebook = ea* titration4 ,inaccurate values %\ld n be eras$ or disc>d$4 ,!y %\ld be reta9$ & m>k$ correct or incorrect1 z indicat$ by ! f9al outcome ( ! titrations4 ,?is cu/om %\ld be rigidly foll[$ 9 all analytical "w4 ,note #a3 ,! end-po9t %\ld be *os5 exactly at ! po9t ( *ange2 any d>k] t9t is unsatisfactory1 s9ce x is impossible to c>ry %ades ( color 9 ! memory & to duplicate !m f day to day4 ,note #b3 ,:ile v>iation ( two p>ts 9 "o ?\s& 9 ! values obta9$ by an inexp]i5c$ analy/ is n excessive1 ! idea mu/ be c>efully avoid$ t ?is is a /&>d = accurate "w to be 6g5]ally appli$64 ,9 _m cases1 aft] exp]i5ce is ga9$1 ! all[able error is less ?an ?is proportion4 ,9 a few cases a l>g] v>iation is p]missible1 b ^! are r>e & c only be recogniz$ by an exp]i5c$ analy/4 ,x is ess5tial t ! beg9n] %\ld acquire at lea/ ! degree ( accuracy indicat$ if he is to become a successful analy/4 ,,/&>dization ,,( ,,hydro*loric ,,acid ,,selection ,,& ,,prep>ation ,,( ,,/&>d ,! selection ( ! be/ sub/ance to be us$ z a /&>d = acid solutions has be5 ! subject ( mu* controv]sy4 ,! "w ( ,lunge 76,zts*r4 angew4 ,*em46 7#aijd71 #h1 #bca71 ,f]guson 76,j4 ,soc4 ,*em4 ,ind46 7#aije71 #bd1 #ghd71 & o!rs1 seems to indicate t ! be/ /&>d is sodium c>bonate prep>$ f sodium bic>bonate by heat+ ! latt] at temp]ature betwe5 #bgj & #cjj;,c4 ,! bic>bonate is easily prep>$ 9 a pure /ate1 & at ! temp]atures nam$ ! decomposition takes place accord+ to ! equation #b;,h,na,c,o#c -- ,na#b;,,co#c ,h#b,o ,,co#b & )\t loss ( any c>bon dioxide f ! sodium c>bonate1 su* z may occur at high] temp]atures4 ,! process is c>ri$ out z describ$ bel[4 ,,proc$ure4--,place 9 a porcela9 crucible ab\t #f grams 7r\ghly weigh$7 ( ! pure/ sodium bic>bonate obta9able4 ,re/ ! crucible ^u a triangle ( iron or copp] wire s plac$ )9 a l>ge crucible t !re is an op5 air space ( ab\t ?ree eigh?s ( an in* betwe5 !m4 ,! l>g] crucible may be ( iron1 nickel or porcela91 z may be mo/ conv5i5t4 ,ins]t ! bulb ( a !rmomet] read+ to #cej;,c4 9 ! bic>bonate1 support+ x ) a clamp s t ! bulb does n re/ on ! bottom ( ! crucible4 ,heat ! outside crucible1 us+ a r small flame1 & raise ! temp]ature ( ! bic>bonate fairly rapidly to #bgj;,c4 ,!n regulate ! heat 9 su* a way t ! temp]ature rises 6sl[ly6 to #cjj;,c4 9 ! c\rse ( a half-h\r4 ,! bic>bonate %\ld be frequ5tly /irr$ ) a clean1 dry1 glass rod1 & aft] /irr+1 %\ld be heap$ up ar\nd ! bulb ( ! !rmomet] 9 su* a way z to cov] x4 ,?is w require att5tion dur+ mo/ ( ! heat+1 z ! temp]ature %\ld n be p]mitt$ to rise above #caj;,c4 = any l5g? ( "t4 ,at ! end ( ! half-h\r remove ! !rmomet] & transf] ! porcela9 crucible1 :i* n[ conta9s sodium c>bonate1 to a desiccator4 ,:5 x is cold1 transf] ! c>bonate to a /opp]$ weigh+ tube or weigh+-bottle4 ,,/&>dization ,,proc$ure4--,clean c>efully ! outside ( a weigh+-tube1 or weigh+-bottle1 conta9+ ! pure sodium c>bonate1 tak+ c>e to h&le x z little z possible aft] wip+4 ,weigh ! tube accurately to #j4jjja gram1 & record ! weight 9 ! notebook4 ,hold ! tube ov] ! top ( a beak] 7#bjj-cjj cc47 & cauti\sly remove ! /opp]1 mak+ sure t no p>ticles fall f x or f ! tube else:]e ?an 9 ! beak]4 ,p\r out f ! tube a portion ( ! c>bonate1 replace ! /opp] & det]m9e approximately h[ mu* has be5 remov$4 ,cont9ue ?is proc$ure until #a4jj to #a4aj grams has be5 tak5 f ! tube4 ,!n weigh ! tube accurately & record ! weight "u ! fir/ weight 9 ! notebook4 ,! diff]5ce 9 ! two weights is ! weight ( ! c>bonate transf]r$ to ! beak]4 ,proce$ 9 ! same way to transf] a second portion ( ! c>bonate f ! tube to ano!r beak] ( ab\t ! same size z ! fir/4 ,! beak]s %\ld be label$ & pla9ly m>k$ to correspond ) ! entries 9 ! notebook4 ,p\r ov] ! c>bonate 9 ea* beak] ab\t #hj cc4 ( wat]1 /ir until solution is complete1 & add two drops ( me?yl orange solution4 ,fill ! burettes ) ! /&>d acid & alkali solutions1 not+ ! initial read+s ( ! burettes & temp]ature ( ! solutions4 ,run 9 acid f ! burette1 /irr+ & avoid+ loss by eff]vesc5ce1 until ! solution has become p9k4 ,wa% d[n ! sides ( ! beak] ) a 6little6 wat] f a wa%-bottle1 & !n run 9 alkali f ! o!r burette until ! p9k is replac$ by yell[2 !n f9i% ! titration z describ$ on page #cg4 ,note ! read+s ( ! burettes aft] ! prop] int]val1 & record !m 9 ! notebook4 ,repeat ! proc$ure1 us+ ! second portion ( sodium c>bonate4 ,apply ! necess>y calibration corrections to ! volumes ( ! solutions us$1 & correct = temp]ature if necess>y4 ,f ! data obta9$1 calculate ! volume ( ! hydro*loric acid solution :i* is equival5t to ! volume ( sodium hydroxide solution us$ 9 ?is titration4 ,subtract ?is volume f ! volume ( hydro*loric acid4 ,! diff]5ce repres5ts ! volume ( acid us$ to react ) ! sodium c>bonate4 ,divide ! weight ( sodium c>bonate by ?is volume 9 cubic c5timet]s1 ?us obta9+ ! weight ( sodium c>bonate equival5t to ea* cubic c5timet] ( ! acid4 ,f ?is weight x is possible to calculate ! correspond+ weight ( ,h,cl 9 ea* cubic c5timet] ( ! acid1 & 9 turn ! relation ( ! acid to ! normal4 ,if1 h[ev]1 x is recall$ t normal solutions are equival5t to ea* o!r1 x w be se5 t ! same result may be m readily rea*$ by divid+ ! weight 9 grams ( sodium c>bonate p] cubic c5timet] j f\nd by titration by ! weight :i* w\ld be conta9$ 9 ! same volume ( a normal solution ( sodium c>bonate4 ,a normal solution ( sodium c>bonate conta9s #ec4j grams p] lit]1 or #j4jecj gram p] cc4 7see page #bi74 ,! relation ( ! acid solution to ! normal is1 !re=e1 calculat$ by divid+ ! weight ( ! c>bonate to :i* ea* cubic c5timet] ( ! acid is equival5t by #j4jecj4 ,! /&>dization mu/ be repeat$ until ! values obta9$ agree )91 at mo/1 two p>ts 9 "o ?\s&4 ,:5 ! /&>d ( ! acid solution has be5 det]m9$1 calculate1 f ! kn[n ratio ( ! two solutions1 ! relation ( ! sodium hydroxide solution to a normal solution 7,notes #a & #b74 ,note #a3 ,9 ! =ego+ proc$ure ! acid solution is /&>diz$ & ! alkali solution ref]r$ to ?is /&>d by calculation4 ,x is equally possible1 if pref]r$1 to /&>dize ! alkali solution4 ,! /&>ds 9 a common use = ?is purpose are purifi$ oxalic acid 7,h#b;,c#b,o#d4b;,h#b,o71 potassium acid oxalate 7,,khc#b,o#d4;,h#b,o or ,,khc#b,o#d71 potassium tetroxalate 7,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o71 or potassium acid t>trate 7,,khc#d,o#f71 ) ! use ( a suitable indicator4 ,! oxalic acid & ! oxalates %\ld be specially prep>$ to insure purity1 ! ma9 difficulty ly+ 9 ! pres]vation ( ! wat] ( cry/allization4 ,x %\ld be not$ t ! acid oxalate & ! acid t>trate ea* conta9 "o hydrog5 atom replaceable by a base1 :ile ! tetroxalate conta9s ?ree su* atoms & ! oxalic acid two4 ,ea* ( ! two salts fir/ nam$ behave1 !re=e1 z monobasic acids1 & ! tetroxalate z a tribasic acid4 ,note #b3 ,x is also possible to /&>dize a hydro*loric acid solution by precipitat+ ! *loride ions z silv] *loride & weigh+ ! precipitate1 z prescrib$ "u ! analysis ( sodium *loride to be describ$ lat]4 ,sulphuric acid solutions may be /&>diz$ by precipitation ( ! sulphate ions z b>ium sulphate & weigh+ ! ignit$ precipitate1 b ! results are n above criticism on acc\nt ( ! difficulty 9 obta9+ l>ge precipitates ( b>ium sulphate :i* are uncontam9at$ by inclosures or are n r$uc$ on ignition4 ,,det]m9ation ,,( ,,! ,,total ,,alkal9e ,,/r5g? ,,( ,,soda ,,a% ,soda a% is crude sodium c>bonate4 ,if made by ! ammonia process x may conta9 also sodium *loride1 sulphate1 & hydroxide2 :5 made by ! ,le ,blanc process x may conta9 sodium sulphide1 silicate1 & alum9ate1 & o!r impurities4 ,"s ( ^!1 notably ! hydroxide1 comb9e ) acids & contribute to ! total alkal9e /r5g?1 b x is cu/om>y to calculate ?is /r5g? 9 t]ms ( sodium c>bonate2 i4e41 z ?\gh no o!r alkali 7 pres5t4 ,,proc$ure4--,9 ord] to secure a sample :i* %all repres5t ! av]age value ( ! a%1 x is well to take at lea/ #e grams4 ,z ?is is too l>ge a quantity = conv5i5t titration1 an aliquot portion ( ! solution is measur$ (f1 repres5t+ "o fif? ( ! entire quantity4 ,?is is accompli%$ z foll[s3 ,weigh out on an analytical balance two samples ( soda a% ( ab\t #e grams ea* into beak]s ( ab\t #ejj cc4 capacity4 7,! weigh+s ne$ be made to c5tigrams only47 ,dissolve ! a% 9 #ge cc4 ( wat]1 w>m+ g5tly1 & filt] (f ! insoluble residue2 wa% ! filt] by fill+ x at lea/ ?ree times ) di/ill$ wat]1 & all[+ x to dra91 add+ ! wa%+s to ! ma9 filtrate4 ,cool ! filtrate to approximately ! /&>d temp]ature ( ! laboratory1 & transf] x to a #bej cc4 measur+ flask1 wa%+ out ! beak] ?or\ghly4 ,add di/ill$ wat] ( laboratory temp]ature until ! l[e/ po9t ( ! m5iscus is level ) ! graduation on ! neck ( ! flask & remove any drops ( wat] t may be on ! neck above ! graduation by means ( a /rip ( filt] pap]2 make ! solution ?or\ghly uni=m by p\r+ x out into a dry beak] & back into ! flask sev]al times4 ,measure (f #ej cc4 ( ! solution 9 a measur+ flask1 or pipette1 ei!r ( :i* be=e use %\ld1 unless !y are dry on ! inside1 be r9s$ out ) at lea/ two small portions ( ! soda a% solution to displace any wat]4 ,if a flask is us$1 fill x to ! graduation ) ! soda a% solution & remove any liquid f ! neck above ! graduation ) filt] pap]4 ,empty x into a beak]1 & wa% out ! small flask1 unless x is graduat$ = 6deliv]y61 us+ small quantities ( wat]1 :i* are add$ to ! liquid 9 ! beak]4 ,a second #ej cc4 portion f ! ma9 solution %\ld be measur$ (f into a second beak]4 ,dilute ! solutions 9 ea* beak] to #ajj cc41 add two drops ( a solution ( me?yl orange 7,note #a7 & titrate = ! alkali ) ! /&>d hydro*loric acid solution1 us+ ! alkali solution to complete ! titration z already prescrib$4 ,f ! volumes ( acid & alkali employ$1 correct$ = burette errors & temp]ature *anges1 & ! data d]iv$ f ! /&>dization1 calculate ! p]c5tage ( alkali pres5t1 assum+ x all to be pres5t z sodium c>bonate 7,note #b74 ,note #a3 ,! hydro*loric acid sets free c>bonic acid :i* is un/able & breaks d[n into wat] & c>bon dioxide1 mo/ ( :i* escapes f ! solution4 ,c>bonic acid is a weak acid &1 z su*1 does n yield a suffici5t conc5tration ( ,h ions to cause ! indicator to *ange to a p9k 7see page #cb74 ,! *emical *anges involv$ may be summ>iz$ z foll[s3 #b;,h1 #b;,cl- #b,na1 ,,co#c-- -- #b,na1 #b;,cl- ,h#b;,,co#c -- ,h#b,o ,,co#b ,note #b3 ,a det]m9ation ( ! alkali pres5t z hydroxide 9 soda a% may be det]m9$ by precipitat+ ! c>bonate by ! addition ( b>ium *loride1 remov+ ! b>ium c>bonate by filtration1 & titrat+ ! alkali 9 ! filtrate4 ,! cau/ic alkali may also be det]m9$ by fir/ us+ ph5olph?ale9 z an indicator1 :i* w %[ by its *ange f p9k to colorless ! po9t at :i* ! cau/ic alkali has be5 neutraliz$ & ! c>bonate has be5 conv]t$ to bic>bonate1 & !n add+ me?yl orange & complet+ ! titration4 ,! am\nt ( acid necess>y to *ange ! me?yl orange to p9k is a measure ( "o half ( ! c>bonate pres5t4 ,! results ( ! d\ble titration furni% ! data necess>y = ! det]m9ation ( ! cau/ic alkali & ( ! c>bonate 9 ! sample4 ,,det]m9ation ,,( ,,! ,,acid ,,/r5g? ,,( ,,oxalic ,,acid ,,proc$ure4--,weigh out two portions ( ! acid ( ab\t #a gram ea*4 ,dissolve ^! 9 #ej cc4 ( w>m wat]4 ,add two drops ( ph5olph?ale9 solution1 & run 9 alkali f ! burette until ! solution is p9k2 add acid f ! o!r burette until ! p9k is j de/roy$1 & !n add #j4c cc4 7n m7 9 excess4 ,heat ! solution to boil+ = ?ree m9utes4 ,if ! p9k returns dur+ ! boil+1 dis*>ge x ) acid & aga9 add #j4c cc4 9 excess & repeat ! boil+ 7,note #a74 ,if ! color does n !n reappe>1 add alkali until x does1 & a 6drop or two6 ( acid 9 excess & boil aga9 = "o m9ute 7,note #b74 ,if no color reappe>s dur+ ?is "t1 complete ! titration 9 ! hot solution4 ,! end-po9t %\ld be ! fa9te/ visible %ade ( color 7or its disappe>ance71 z ! same difficulty w\ld exi/ "h z ) me?yl orange if an attempt 7 made to mat* %ades ( p9k4 ,f ! correct$ volume ( alkali requir$ to react ) ! oxalic acid1 calculate ! p]c5tage ( ! cry/alliz$ acid 7,h#b;,c#b,o#d4b;,h#b,o7 9 ! sample 7,note #c74 ,note #a3 ,all comm]cial cau/ic soda su* z t f :i* ! /&>d solution 0 made conta9s "s sodium c>bonate4 ,?is reacts ) ! oxalic acid1 sett+ free c>bonic acid1 :i*1 9 turn1 =ms sodium bic>bonate ) ! rema9+ c>bonate3 ,h#b;,,co#c ,na#b;,,co#c -- #b;,h,na,c,o#c4 ,?is comp\nd does n hydrolyze suffici5tly to furni% en\gh ,,oh- ions to cause ph5olph?ale9 to rema9 p9k2 h5ce1 ! color ( ! indicator is dis*>g$ 9 cold solutions at ! po9t at :i* bic>bonate is =m$4 ,if1 h[ev]1 ! solution is heat$ to boil+1 ! bic>bonate loses c>bon dioxide & wat]1 & rev]ts to sodium c>bonate1 :i* causes ! indicator to become aga9 p9k3 #b;,h,na,c,o#c -- ,h#b,o ,,co#b ,na#b;,,co#c4 ,by add+ successive portions ( hydro*loric acid & boil+1 ! c>bonate is ultimately all br\ght into reaction4 ,! /ud5t %\ld make sure t ! diff]5ce 9 behavior ( ! two indicators1 me?yl orange & ph5olph?ale91 is und]/ood4 ,note #b3 ,hydro*loric acid is volatiliz$ f aque\s solutions1 except su* z are v dilute4 ,if ! directions 9 ! proc$ure are /rictly foll[$1 no loss ( acid ne$ be fe>$1 b ! am\nt add$ 9 excess %\ld n be great] ?an #j4c-j4d cc4 ,note #c3 ,att5tion has already be5 call$ to ! fact t ! color *anges 9 ! diff]5t indicators occur at v>y+ conc5trations ( ,h or ,,oh- ions4 ,!y d n indicate exact !oretical neutrality1 b a p>ticul> indicator always %[s its color *ange at a p>ticul> conc5tration ( ,h or ,,oh- ions4 ,! results ( titration ) a giv5 indicator are1 !re=e1 comp>able4 ,z a matt] ( fact1 a small error is involv$ 9 ! proc$ure z outl9$ above4 ,! comp>ison ( ! acid & alkali solutions 0 made1 us+ me?yl orange z an indicator1 :ile ! titration ( ! oxalic acid is made ) ! use ( ph5olph?ale94 ,= our pres5t purposes ! small error may be neglect$ b1 if "t p]mits1 ! /ud5t is recomm5d$ to /&>dize ! alkali solution aga9/ "o ( ! sub/ances nam$ 9 ,note #a1 page #da1 & also to asc]ta9 ! comp>ative value ( ! acid & alkali solutions1 us+ ph5olph?ale9 z indicator ?r\gh\t1 & conduct+ ! titrations z describ$ above4 ,?is w insure complete accuracy4 ,,ii4 ,,oxidation ,,processes ,,g5]al ,,discussion ,9 ! oxidation processes ( volumetric analysis /&>d solutions ( oxidiz+ ag5ts & ( r$uc+ ag5ts take ! place ( ! acid & alkali solutions ( ! neutralization processes already /udi$4 ,j z an acid solution 0 ! pr9cipal reag5t 9 alkalimetry1 & ! alkali solution us$ only to make c]ta9 ( ! end-po9t1 ! solution ( ! oxidiz+ ag5t is ! pr9cipal reag5t = ! titration ( sub/ances ex]t+ a r$uc+ action4 ,x is1 9 g5]al1 true t oxidizable sub/ances are det]m9$ by 6direct6 titration1 :ile oxidiz+ sub/ances are det]m9$ by 6indirect6 titration4 ,! important oxidiz+ ag5ts employ$ 9 volumetric solutions are potassium bi*romate1 potassium p]mang5ate1 potassium f]ricyanide1 iod9e1 f]ric *loride1 & sodium hypo*lorite4 ,! important r$uc+ ag5ts :i* are us$ 9 ! =m ( /&>d solutions are f]r\s sulphate 7or f]r\s ammonium sulphate71 oxalic acid1 sodium ?iosulphate1 /ann\s *loride1 ars5i\s acid1 & potassium cyanide4 ,o!r r$uc+ ag5ts1 z sulphur\s acid1 sulphuret$ hydrog51 & z9c 7nasc5t hydrog571 may take "p 9 ! processes1 b n z /&>d solutions4 ,! mo/ important comb9ations among ! =ego+ are3 ,potassium bi*romate & f]r\s salts2 potassium p]manganate & f]r\s salts2 potassium p]manganate & oxalic acid1 or its d]ivatives2 iod9e & sodium ?iosulphate2 hypo*lorites & ars5i\s acid4 ,,bi*romate ,,process ,,= ,,! ,,det]m9ation ,,( ,,iron ,f]r\s salts may be promptly & completely oxidiz$ to f]ric salts1 ev5 9 cold solution1 by ! addition ( potassium bi*romate1 provid$ suffici5t acid is pres5t to hold 9 solution ! f]ric & *romic comp\nds :i* are =m$4 ,! acid may be ei!r hydro*loric or sulphuric1 b ! =m] is usually pref]r$1 s9ce x is by f> ! be/ solv5t = iron & its comp\nds4 ,! reaction 9 ! pres5ce ( hydro*loric acid is z foll[s3 #f;,fe,cl#b ,k#b;,cr#b,o#g #ad;,h,cl -- #f;,fe,cl#c #b;,cr,cl#c #b,k,cl #g;,h#b,o4 ,,normal ,,solutions ,,( ,,oxidiz+ ,,or ,,r$uc+ ,,ag5ts ,x w be recall$ t ! sy/em ( normal solutions is bas$ ^u ! equival5ce ( ! reag5ts :i* !y conta9 to #h grams ( oxyg5 or #a gram ( hydrog54 ,a normal solution ( an oxidiz+ ag5t %\ld1 !re=e1 conta9 t am\nt p] lit] :i* is equival5t 9 oxidiz+ p[] to #h grams ( oxyg52 a normal r$uc+ solution mu/ be equival5t 9 r$uc+ p[] to #a gram ( hydrog54 ,9 ord] to det]m9e :at ! am\nt p] lit] w be x is necess>y to "k h[ ! reag5ts ent] into reaction4 ,! two solutions to be employ$ 9 ! process "u consid]ation are ^? ( potassium bi*romate & f]r\s sulphate4 ,! reaction betwe5 !m1 9 ! pres5ce ( an excess ( sulphuric acid1 may be express$ z foll[s3 #f;,fe,s,o#d ,k#b;,cr#b,o#g #g;,h#b,,s#d -- #c;,fe#b7,,s#d7c ,k#b,,s#d ,cr#b7,,s#d7c #g;,h#b,o4 ,if ! comp\nds ( iron & *romium1 ) :i* alone we are n[ conc]n$1 be writt5 9 su* a way z to %[ ! oxides ( ^! elem5ts 9 ea*1 !y w\ld appe> z foll[s3 ,on ! left-h& side ( ! equation #f7;,fe,o4,,s#c7 & ,k#b,o4#b;,cr,o#c2 on ! "r-h& side1 #c7;,fe#b,o#c4c,,s#c7 & ,cr#b,o#c4c,,s#c4 ,a c>eful inspection %[s t !re are ?ree less oxyg5 atoms associat$ ) *romium atoms on ! "r-h& side ( ! equation ?an on ! left-h&1 b !re are ?ree m oxyg5 atoms associat$ ) iron atoms on ! "r ?an on ! left4 ,9 o!r words1 a molecule ( potassium bi*romate has giv5 up ?ree atoms ( oxyg5 = oxidation purposes2 i4e41 a molecul> weight 9 grams ( ! bi*romate 7#bid4b7 w furni% #c ,x #af or #dh grams ( oxyg5 = oxidation purposes4 ,z ?is #dh grams is six times #h grams1 ! basis ( ! sy/em1 ! normal solution ( potassium bi*romate %\ld conta9 p] lit] "o six? ( #bid4b grams or #di4jc grams4 ,a fur!r inspection ( ! dissect$ comp\nds above %[s t six molecules ( ,fe,o4,,s#c 7 requir$ to react ) ! ?ree atoms ( oxyg5 f ! bi*romate4 ,f ! two equations #c;,h#b #c,o -- #c;,h#b,o #f7;,fe,o4,,s#c7 #c,o -- #c7;,fe#b,o#c4c,,s#c7 x is pla9 t "o molecule ( f]r\s sulphate is equival5t to "o atom ( hydrog5 9 r$uc+ p[]2 !re=e "o molecul> weight 9 grams ( f]r\s sulphate 7#aea4i7 is equival5t to #a gram ( hydrog54 ,s9ce ! f]r\s sulphate cry/all9e =m has ! =mula ,fe,s,o#d4g;,h#b,o1 a normal r$uc+ solution ( ?is cry/all9e salt %\ld conta9 #bgg4i grams p] lit]4 ,,prep>ation ,,( ,,solutions 6,approximate ,/r5g? #j4a ,n6 ,x is possible to purify comm]cial potassium bi*romate by recry/allization f hot wat]4 ,x mu/ !n be dri$ & cauti\sly heat$ to fusion to expel ! la/ traces ( moi/ure1 b n suffici5tly high to expel any oxyg54 ,! pure salt ?us prep>$1 may be weigh$ out directly1 dissolv$1 & ! solution dilut$ 9 a graduat$ flask to a def9ite volume4 ,9 ?is case no /&>dization is made1 z ! normal value c be calculat$ directly4 ,x is1 h[ev]1 m g5]ally cu/om>y to /&>dize a solution ( ! comm]cial salt by comp>ison ) "s sub/ance ( def9ite composition1 z describ$ bel[4 ,,proc$ure4--,pulv]ize ab\t #e grams ( potassium bi*romate ( good quality4 ,dissolve ! bi*romate 9 di/ill$ wat]1 transf] ! solution to a lit] bottle1 & dilute to approximately #ajjj cc4 ,%ake ?or\ghly until ! solution is uni=m4 ,to prep>e ! solution ( ! r$uc+ ag5t1 pulv]ize ab\t #bh grams ( f]r\s sulphate 7,fe,s,o#d4g;,h#b,o7 or ab\t #dj grams ( f]r\s ammonium sulphate 7,fe,s,o#d47,,nh#d7b,,s#d4f;,h#b,o7 & dissolve 9 di/ill$ wat] conta9+ #e cc4 ( conc5trat$ sulphuric acid4 ,transf] ! solution to a lit] bottle1 add #e cc4 conc5trat$ sulphuric acid1 make up to ab\t #ajjj cc4 & %ake vigor\sly to insure uni=mity4 ,,indicator ,,solution ,no indicator is kn[n :i*1 l me?yl orange1 c be us$ )9 ! solution1 to %[ :5 ! oxidation process is complete4 ,in/ead1 an outside indicator solution is employ$ to :i* drops ( ! titrat$ solution are transf]r$ = te/+4 ,! reag5t us$ is potassium f]ricyanide1 :i* produces a blue precipitate 7or color7 ) f]r\s comp\nds z long z !re are unoxidiz$ f]r\s ions 9 ! titrat$ solution4 ,drops ( ! indicator solution are plac$ ^u a glaz$ porcela9 tile1 or ^u :ite c>dbo>d :i* has be5 coat$ ) p>aff9 to r5d] x wat]pro(1 & drops ( ! titrat$ solution are transf]r$ to ! indicator on ! end ( a /irr+ rod4 ,:5 ! oxidation is ne>ly complet$ only v small am\nts ( ! f]r\s comp\nds rema9 unoxidiz$ & ! reaction ) ! indicator is no long] in/antane\s4 ,x is necess>y to all[ a brief "t to elapse be=e det]m9+ t no blue color is =m$4 ,?irty seconds is a suffici5t int]val1 & %\ld be adopt$ ?r\gh\t ! analytical proc$ure4 ,if left too long1 ! comb9$ effect ( light & du/ f ! air w cause a r$uction ( ! f]ric comp\nds already =m$ & a resultant blue w appe> :i* misleads ! obs]v] ) respect to ! true end-po9t4 ,! indicator solution mu/ be highly dilut$1 o!rwise its own color int]f]es ) accurate obs]vation4 ,prep>e a fre% solution1 z ne$$ ea* day1 by dissolv+ a cry/al ( potassium f]ricyanide ab\t ! size ( a p9's head 9 #be cc4 ( di/ill$ wat]4 ,! salt %\ld be c>efully te/$ ) f]ric *loride = ! pres5ce ( f]rocyanides1 :i* give a blue color ) f]ric salts4 ,9 case ( ne$1 ! f]ricyanide c be purifi$ by add+ to its solution a little brom9e wat] & recry/alliz+ ! comp\nd4 ,,comp>ison ,,( ,,oxidiz+ ,,& ,,r$uc+ ,,solutions ,,proc$ure4--,fill "o burette ) ea* ( ! solutions1 obs]v+ ! g5]al proc$ure ) respect to clean+ & r9s+ already prescrib$4 ,! bi*romate solution is pref]ably to be plac$ 9 a glass-/opp]$ burette4 ,run out f a burette into a beak] ( ab\t #cjj cc4 capacity ne>ly #dj cc4 ( ! f]r\s solution1 add #ae cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab7 & #aej cc4 ( wat] & run 9 ! bi*romate solution f ano!r burette4 ,s9ce bo? solutions are approximately t5?-normal1 #ce cc4 ( ! bi*romate solution may be add$ )\t te/+4 ,te/ at t po9t by remov+ a v small drop ( ! iron solution on ! end ( a /irr+ rod1 mix+ x ) a drop ( indicator on ! tile 7,note #a74 ,if a blue precipitate appe>s at once1 #j4e cc4 ( ! bi*romate solution may be add$ be=e te/+ aga94 ,! /irr+ rod :i* has t\*$ ! indicator %\ld be dipp$ 9 di/ill$ wat] be=e return+ x to ! iron solution4 ,z soon z ! blue appe>s to be less int5se1 add ! bi*romate solution 9 small portions1 f9ally a s+le drop at a "t1 until ! po9t is rea*$ at :i* no blue color appe>s aft] ! lapse ( ?irty seconds f ! "t ( mix+ solution & indicator4 ,at ! close ( ! titration a l>ge drop ( ! iron solution %\ld be tak5 = ! te/4 ,to det]m9e ! end-po9t beyond any "q1 z soon z ! ?irty seconds h elaps$ remove ano!r drop ( ! solution ( ! same size z t la/ tak5 & mix x ) ! indicator1 plac+ x beside ! la/ previ\s te/4 ,if ?is la/ previ\s te/ %[s a blue t9t 9 comp>ison ) ! fre% mixture1 ! end-po9t has n be5 rea*$2 if no diff]5ce c be not$ ! reaction is complete4 ,%\ld ! end-po9t be ov]/epp$1 a little m ( ! f]r\s solution may be add$ & ! end-po9t def9itely fix$4 ,f ! volumes ( ! solutions us$1 aft] apply+ corrections = burette read+s1 &1 if ne$ be1 = ! temp]ature ( solutions1 calculate ! value ( ! f]r\s solution 9 t]ms ( ! oxidiz+ solution4 ,note #a3 ,! accuracy ( ! "w may be mu* impair$ by ! removal ( unnecess>ily l>ge quantities ( solution = ! te/s4 ,at ! beg9n+ ( ! titration1 :ile mu* f]r\s iron is /ill pres5t1 ! end ( ! /irr+ rod ne$ only be moi/ ) ! solution2 b at ! close ( ! titration drops ( consid]able size may prop]ly be tak5 = ! f9al te/s4 ,! /irr+ rod %\ld be wa%$ to prev5t transf] ( indicator to ! ma9 solution4 ,?is cauti\s removal ( solution does n s]i\sly affect ! accuracy ( ! det]m9ation1 z x w be not$ t ! volume ( ! titrat$ solution is ab\t #bjj cc4 & ! portions remov$ are v small4 ,moreov]1 if ! proc$ure is foll[$ z prescrib$1 ! conc5tration ( unoxidiz$ iron decreases v rapidly z ! titration is c>ri$ out s t :5 ! f9al te/s are made1 ?\gh l>ge drops may be tak51 ! am\nt ( f]r\s iron is n suffici5t to produce any appreciable error 9 results4 ,if ! end-po9t is det]m9$ z prescrib$1 x c be z accurately fix$ z t ( o!r me?ods2 & if a f]r\s solution is at h&1 ! titration ne$ consume h>dly m "t ?an t ( ! p]manganate process to be describ$ lat] on4 ,,/&>dization ,,( ,,potassium ,,bi*romate ,,solutions 6,selection ( a ,/&>d6 ,a sub/ance :i* w s]ve satisfactorily z a /&>d = oxidiz+ solutions mu/ possess c]ta9 specific prop]ties3 ,x mu/ be ( accurately kn[n composition & def9ite 9 its behavior z a r$uc+ ag5t1 & x mu/ be p]man5t aga9/ oxidation 9 ! air1 at lea/ = consid]able p]iods4 ,su* /&>ds may take ! =m ( pure cry/all9e salts1 su* z f]r\s ammonium sulphate1 or may be 9 ! =m ( iron wire or an iron ore ( kn[n iron cont5t4 ,x is n necess>y t ! /&>d %\ld be ( #ajj p] c5t purity1 provid$ ! cont5t ( ! active r$uc+ ag5t is kn[n & no int]f]+ sub/ances are pres5t4 ,! two sub/ances mo/ commonly us$ z /&>ds = a bi*romate solution are f]r\s ammonium sulphate & iron wire4 ,a /&>d wire is to be pur*as$ 9 ! m>ket :i* answ]s ! purpose well1 & its iron cont5t may be det]m9$ = ea* lot pur*as$ by a numb] ( gravimetric det]m9ations4 ,x may be/ be pres]v$ 9 j>s conta9+ calcium *loride1 b ?is mu/ n be all[$ to come into contact ) ! wire4 ,x %\ld1 h[ev]1 ev5 !n be exam9$ c>efully = ru/ be=e use4 ,if pure f]r\s ammonium sulphate is us$ z ! /&>d1 cle> cry/als only %\ld be select$4 ,x is p]haps ev5 bett] to det]m9e by gravimetric me?ods once = all ! iron cont5t ( a l>ge comm]cial sample :i* has be5 gr\nd & well mix$4 ,?is salt is p]man5t ov] long p]iods if kept 9 /opp]$ conta9]s4 ,,/&>dization ,,proc$ure4--,weigh out two portions ( iron wire ( ab\t #j4bd-j4bf gram ea*1 exam9+ ! wire c>efully = ru/4 ,x %\ld be h&l$ & wip$ ) filt] pap] 7n t\*$ by ! f+]s71 %\ld be weigh$ on a wat*-glass1 & be b5t 9 su* a way z n to int]f]e ) ! movem5t ( ! balance4 ,place #cj cc4 ( hydro*loric acid 7sp4 gr4 #a4ab7 9 ea* ( two #cjj cc4 ,erl5mey] flasks1 cov] !m ) wat*-glasses1 & br+ ! acid j to boil+4 ,remove !m f ! flame & drop 9 ! portions ( wire1 tak+ great c>e to avoid loss ( liquid dur+ solution4 ,boil = two or ?ree m9utes1 keep+ ! flasks cov]$ 7,note #a71 !n wa% ! sides ( ! flasks & ! wat*-glass ) a little wat] & add /ann\s *loride solution to ! hot liquid 6f a dropp]6 until ! solution is colorless1 b avoid m ?an a drop or two 9 excess 7,note #b74 ,dilute ) #aej cc4 ( wat] & cool 6completely64 ,:5 cold1 add rapidly ab\t #cj cc4 ( m]curic *loride solution4 ,all[ ! solutions to /& ab\t ?ree m9utes & !n titrate )\t fur!r delay 7,note #c71 add ab\t #ce cc4 ( ! /&>d solution at once & f9i% ! titration z prescrib$ above1 mak+ use ( ! f]r\s solution if ! end-po9t %\ld be pass$4 ,f ! correct$ volumes ( ! bi*romate solution requir$ to oxidize ! iron actually "k to be pres5t 9 ! wire1 calculate ! relation ( ! /&>d solution to ! normal4 ,repeat ! /&>dization until ! results are concordant )9 at lea/ two p>ts 9 "o ?\s&4 ,note #a3 ,! hydro*loric acid is add$ to ! f]r\s solution to insure ! pres5ce ( at lea/ suffici5t free acid = ! titration1 z requir$ by ! equation on page #dh4 ,! solution ( ! wire 9 hot acid & ! %ort boil+ insure ! removal ( comp\nds ( hydrog5 & c>bon :i* are =m$ f ! small am\nt ( c>bon 9 ! iron4 ,^! might be act$ ^u by ! bi*romate if n expell$4 ,note #b3 ,x is pla9 t all ! iron mu/ be r$uc$ to ! f]r\s condition be=e ! titration beg9s1 z "s oxidation may h occurr$ f ! oxyg5 ( ! air dur+ solution4 ,x is also evid5t t any excess ( ! ag5t us$ to r$uce ! iron mu/ be remov$2 o!rwise x w react ) ! bi*romate add$ lat]4 ,! reag5ts available = ! r$uction ( iron are /ann\s *loride1 sulphur\s acid1 sulphuret$ hydrog51 & z9c2 ( ^! /ann\s *loride acts mo/ readily1 ! completion ( ! reaction is mo/ easily not$1 & ! excess ( ! reag5t is mo/ readily remov$4 ,! latt] object is accompli%$ by oxidation to /annic *loride by means ( m]curic *loride add$ 9 excess1 z ! m]curic salts h no effect ^u f]r\s iron or ! bi*romate4 ,! reactions involv$ are3 #b;,fe,cl#c ,sn,cl#b -- #b;,fe,cl#b ,sn,cl#d ,sn,cl#b #b;,hg,cl#b -- ,sn,cl#d #b;,hg,cl ,! m]cur\s *loride is precipitat$4 ,x is ess5tial t ! solution %\ld be cold & t ! /ann\s *loride %\ld n be pres5t 9 great excess1 o!rwise a second>y reaction takes place1 result+ 9 ! r$uction ( ! m]cur\s *loride to metallic m]cury3 ,sn,cl#b #b;,hg,cl -- ,sn,cl#d #b;,hg4 ,! occurr5ce ( ?is second>y reaction is indicat$ by ! d>k5+ ( ! precipitate2 &1 s9ce potassium bi*romate oxidizes ?is m]cury sl[ly1 solutions 9 :i* x has be5 precipitat$ are wor?less z iron det]m9ations4 ,note #c3 ,! solution %\ld be all[$ to /& ab\t ?ree m9utes aft] ! addition ( m]curic *loride to p]mit ! complete deposition ( m]cur\s *loride4 ,x %\ld !n be titrat$ )\t delay to avoid possible reoxidation ( ! iron by ! oxyg5 ( ! air4 ,,det]m9ation ,,( ,,iron ,,9 ,,limonite ,,proc$ure4--,gr9d ! m9]al 7,note #a7 to a f9e p[d]4 ,weigh out accurately two portions ( ab\t #j4e gram 7,note #b7 into porcela9 crucibles2 heat ^! crucibles to dull r$ness = t5 m9utes1 all[ !m to cool1 & place !m1 ) _! cont5ts1 9 beak]s conta9+ #cj cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab74 ,heat at a temp]ature j bel[ boil+ until ! undissolv$ residue is :ite or until solv5t action has ceas$4 ,if ! residue is :ite1 or kn[n to be free f iron1 x may be neglect$ & ne$ n be remov$ by filtration4 ,if a d>k residue rema9s1 collect x on a filt]1 wa% free f hydro*loric acid1 & ignite ! filt] 9 a plat9um crucible 7,note #c74 ,mix ! a% ) five times its weight ( sodium c>bonate & heat to fusion2 cool1 & dis9tegrate ! fus$ mass ) boil+ wat] 9 ! crucible4 ,unite ?is solution & precipitate 7if any7 ) ! acid solution1 tak+ c>e to avoid loss by eff]vesc5ce4 ,wa% out ! crucible1 heat ! acid solution to boil+1 add /ann\s *loride solution until x is colorless1 avoid+ a l>ge excess 7,note #d72 cool1 & :5 6cold61 add #dj cc4 ( m]curic *loride solution1 dilute to #bjj cc41 & proce$ ) ! titration z already describ$4 ,f ! /&>dization data already obta9$1 & ! kn[n weight ( ! sample1 calculate ! p]c5tage ( iron 7,fe7 9 ! limonite4 ,note #a3 ,limonite is select$ z a repres5tative ( iron ores 9 g5]al4 ,x is a native1 hydrat$ oxide ( iron4 ,x frequ5tly occurs 9 or ne> peat b$s & conta9s m or less organic matt] :i*1 if br\ght into solution1 w\ld be act$ ^u by ! potassium bi*romate4 ,?is organic matt] is de/roy$ by roa/+4 ,s9ce a high temp]ature t5ds to less5 ! solubility ( f]ric oxide1 ! heat %\ld n be rais$ above l[ r$ness4 ,note #b3 ,x is sometimes advantage\s to dissolve a l>ge portion--say #e grams--& to take "o t5? ( x = titration4 ,! sample w !n repres5t m closely ! av]age value ( ! ore4 ,note #c3 ,a plat9um crucible may be us$ = ! roa/+ ( ! limonite & mu/ be us$ = ! fusion ( ! residue4 ,:5 us$1 x mu/ n be all[$ to rema9 9 ! acid solution ( f]ric *loride = any l5g? ( "t1 s9ce ! plat9um is attack$ & dissolv$1 & ! plat9ic *loride is lat] r$uc$ by ! /ann\s *loride1 & 9 ! r$uc$ condition reacts ) ! bi*romate1 ?us introduc+ an error4 ,x %\ld also be not$ t copp] & antimony int]f]e ) ! det]m9ation ( iron by ! bi*romate process4 ,note #d3 ,! quantity ( /ann\s *loride requir$ = ! r$uction ( ! iron 9 ! limonite w be mu* l>g] ?an t add$ to ! solution ( iron wire1 9 :i* ! iron 0 ma9ly already 9 ! f]r\s condition4 ,x %\ld1 h[ev]1 be add$ f a dropp] to avoid an unnecess>y excess4 ,,det]m9ation ,,( ,,*romium ,,9 ,,*rome ,,iron ,,ore ,,proc$ure4--,gr9d ! *rome iron ore 7,note #a7 9 an agate mort> until no grit is p]ceptible "u ! pe/le4 ,weigh out two portions ( #j4e gram ea* into iron crucibles :i* h be5 sc\r$ inside until bright 7,note #b74 ,weigh out on a wat*-glass 7,note #c71 us+ ! r\gh balances1 #e grams ( dry sodium p]oxide = ea* portion1 & p\r ab\t ?ree qu>t]s ( ! p]oxide ^u ! ore4 ,mix ore & flux by ?or\gh /irr+ ) a dry glass rod4 ,!n cov] ! mixture ) ! rema9d] ( ! p]oxide4 ,place ! crucible on a triangle & raise ! temp]ature 6sl[ly6 to ! melt+ po9t ( ! flux1 us+ a l[ flame1 & hold+ ! lamp 9 ! h& 7,note #d74 ,ma9ta9 ! fusion = five m9utes1 & /ir con/antly ) a /\t iron wire1 b d n raise ! temp]ature above mod]ate r$ness 7,notes #e & #f74 ,all[ ! crucible to cool until x c be com=tably h&l$ 7,note #g7 & !n place x 9 a #cjj cc4 beak]1 & cov] x ) di/ill$ wat] 7,note #h74 ,! beak] mu/ be c>efully cov]$ to avoid loss dur+ ! dis9tegration ( ! fus$ mass4 ,:5 ! evolution ( gas ceases1 r9se (f & remove ! crucible2 !n heat ! solution 6:ile /ill alkal9e6 to boil+ = fifte5 m9utes4 ,all[ ! liquid to cool = a few m9utes2 !n acidify ) dilute sulphuric acid 7#a3e71 add+ #aj cc4 9 excess ( ! am\nt necess>y to dissolve ! f]ric hydroxide 7,note #i74 ,dilute to #bjj cc41 cool1 add f a burette an excess ( a /&>d f]r\s solution1 & titrate = ! excess ) a /&>d solution ( potassium bi*romate1 us+ ! outside indicator 7,note #aj74 ,f ! correct$ volumes ( ! two /&>d solutions1 & _! relations to normal solutions1 calculate ! p]c5tage ( *romium 9 ! ore4 ,note #a3 ,*rome iron ore is ess5tially a f]r\s *romite1 or comb9ation ( ,fe,o & ,cr#b,o#c4 ,x mu/ be r$uc$ to a /ate ( f9e subdivision to ensure a prompt reaction ) ! flux4 ,note #b3 ,! sc\r+ ( ! iron crucible is r5d]$ mu* easi] if x is fir/ heat$ to bright r$ness & plung$ into cold wat]4 ,9 ?is process oily matt] is burn$ (f & adh]+ scale is caus$ to *ip (f :5 ! hot crucible contracts rapidly 9 ! cold wat]4 ,note #c3 ,sodium p]oxide mu/ be kept (f ( balance pans & %\ld n be weigh$ out on pap]1 z is ! usual practice 9 ! r\gh weigh+ ( *emicals4 ,if pap] to :i* ! p]oxide is adh]+ is expos$ to moi/ air x is likely to take fire z a result ( ! absorption ( moi/ure1 & consequ5t evolution ( heat & lib]ation ( oxyg54 ,note #d3 ,! lamp %\ld nev] be all[$ to rema9 "u ! crucible1 z ?is w raise ! temp]ature to a po9t at :i* ! crucible itself is rapidly attack$ by ! flux & burn$ ?r\gh4 ,note #e3 ,! sodium p]oxide acts z bo? a flux & an oxidiz+ ag5t4 ,! *romic oxide is dissolv$ by ! flux & oxidiz$ to *romic anhydride 7,cr,o#c7 :i* comb9es ) ! alkali to =m sodium *romate4 ,! iron is oxidiz$ to f]ric oxide4 ,note #f3 ,! sodium p]oxide _c be us$ 9 porcela91 plat9um1 or silv] crucibles4 ,x attacks iron & nickel z well2 b crucibles made f ^! metals may be us$ if c>e is ex]cis$ to keep ! temp]ature z l[ z possible4 ,pref]5ce is "h giv5 to iron crucibles1 because ! result+ f]ric hydroxide is m readily br\ght into solution ?an ! nickelic oxide f a nickel crucible4 ,! p]oxide mu/ be dry1 & mu/ be protect$ f any admixture ( du/1 pap]1 or ( organic matt] ( any k9d1 o!rwise explosions may ensue4 ,note #g3 ,:5 an iron crucible is employ$ x is desirable to all[ ! fusion to become ne>ly cold be=e x is plac$ 9 wat]1 o!rwise scales ( magnetic iron oxide may sep>ate f ! crucible1 :i* by sl[ly dissolv+ 9 acid =m f]r\s sulphate1 :i* r$uces ! *romate4 ,note #h3 ,^u treatm5t ) wat] ! *romate passes into solution1 ! f]ric hydroxide rema9s undissolv$1 & ! excess ( p]oxide is decompos$ ) ! evolution ( oxyg54 ,! subsequ5t boil+ insures ! complete decomposition ( ! p]oxide4 ,unless ?is is complete1 hydrog5 p]oxide is =m$ :5 ! solution is acidifi$1 & ?is reacts ) ! bi*romate1 r$uc+ x & introduc+ a s]i\s error4 ,note #i3 ,! addition ( ! sulphuric acid conv]ts ! sodium *romate to bi*romate1 :i* behaves exactly l potassium bi*romate 9 acid solution4 ,note #aj3 ,if a /&>d solution ( a f]r\s salt is n at h&1 a weight ( iron wire some:at 9 excess ( ! am\nt :i* w\ld be requir$ if ! *romite 7 pure ,fe,o4,cr#b,o#c may be weigh$ out & dissolv$ 9 sulphuric acid2 aft] r$uction ( all ! iron by /ann\s *loride & ! addition ( m]curic *loride1 ?is solution may be p\r$ into ! *romate solution & ! excess ( iron det]m9$ by titration ) /&>d bi*romate solution4 ,,p]manganate ,,process ,,= ,,! ,,det]m9ation ,,( ,,iron ,potassium p]manganate oxidizes f]r\s salts 9 cold1 acid solution promptly & completely to ! f]ric condition1 :ile 9 hot acid solution x also ent]s into a def9ite reaction ) oxalic acid1 by :i* ! latt] is oxidiz$ to c>bon dioxide & wat]4 ,! reactions involv$ are ^!3 #aj;,fe,s,o#d #b,k,mn,o#d #h;,h#b,s#d -- #e;,fe#b7,,s#d7c ,k#b,,s#d #b,mn,s,o#d #h;,h#b,o #e;,c#b;,h#b,o#d7b;,h#b,o7 #b,k,mn,o#d #c;,h#b,,s#d -- ,k#b,,s#d #b,mn,s,o#d #aj;,,co#b #a ,h#b,o4 ,^! are ! fundam5tal reactions ^u :i* ! ext5sive use ( potassium p]manganate dep5ds2 b besides iron & oxalic acid ! p]manganate ent]s into reaction ) antimony1 t91 copp]1 m]cury1 & manganese 7! latt] only 9 neutral solution71 by :i* ^! metals are *ang$ f a l[] to a high] /ate ( oxidation2 & x also reacts ) sulphur\s acid1 sulphuret$ hydrog51 nitr\s acid1 f]rocyanides1 & mo/ soluble organic bodies4 ,x %\ld be not$1 h[ev]1 t v few ( ^! organic comp\nds react quantitatively ) ! p]manganate1 z is ! case ) oxalic acid & ! oxalates4 ,potassium p]manganate is act$ ^u by hydro*loric acid2 ! action is rapid 9 hot or conc5trat$ solution 7p>ticul>ly 9 ! pres5ce ( iron salts1 :i* appe> to act z catalyz]s1 increas+ ! velocity ( ! reaction71 b sl[ 9 cold1 dilute solutions4 ,h[ev]1 ! great] solubility ( iron comp\nds 9 hydro*loric acid makes x desirable to use ?is acid z a solv5t1 & exp]im5ts made ) ?is end 9 view h %[n t 9 cold1 dilute hydro*loric acid solution1 to :i* consid]able quantities ( mangan\s sulphate & an excess ( phosphoric acid h be5 add$1 x is possible to obta9 satisfactory results4 ,x is also possible to replace ! hydro*loric acid by evaporat+ ! solutions ) an excess ( sulphuric acid until ! latt] fumes4 ,?is proc$ure is some:at m "t-consum+1 b ! end-po9t ( ! p]manganate titration is m p]man5t4 ,bo? proc$ures are describ$ bel[4 ,potassium p]manganate has an int5se color+ p[]1 & s9ce ! solution result+ f ! oxidation ( ! iron & ! r$uction ( ! p]manganate is colorless1 ! latt] becomes its own indicator4 ,! slighte/ excess is indicat$ ) great accuracy by ! p9k color ( ! solution4 ,,prep>ation ,,( ,a ,,/&>d ,,solution 6,approximate ,/r5g? #j4a ,n6 ,a /udy ( ! reactions giv5 above :i* repres5t ! oxidation ( f]r\s comp\nds by potassium p]manganate1 %[s t !re are #b molecules ( ,k,mn,o#d & #aj molecules ( ,fe,s,o#d on ! left-h& side1 & #b molecules ( ,mn,s,o#d & #e molecules ( ,fe#b7,,s#d7e on ! "r-h& side4 ,consid]+ only ^! comp\nds1 & writ+ ! =mulas 9 su* a way z to %[ ! oxides ( ! elem5ts 9 ea*1 ! equation becomes3 ,k#b,o4,mn#b,o#g #aj7;,fe,o4,,s#c7 -- ,k#b,o4,,s#c #b7,mn,o4,,s#c7 #e7;,fe#b,o#c4c,,s#c74 ,f ?is x appe>s t two molecules ( ,k,mn,o#d 7or #caf4j grams7 h giv5 up five atoms 7or #hj grams7 ( oxyg5 to oxidize ! f]r\s comp\nd4 ,s9ce #h grams ( oxyg5 is ! basis ( normal oxidiz+ solutions & #hj grams ( oxyg5 are suppli$ by #caf4j grams ( ,k,mn,o#d1 ! normal solution ( ! p]manganate %\ld conta91 p] lit]1 #caf4j_/aj grams1 or #ca4fj grams 7,note #a74 ,! prep>ation ( an approximately t5?-normal solution ( ! reag5t may be c>ri$ out z foll[s3 ,,proc$ure4--,dissolve ab\t #c4be grams ( potassium p]manganate cry/als 9 approximately #ajjj cc4 ( di/ill$ wat] 9 a l>ge beak]1 or cass]ole4 ,heat sl[ly & :5 ! cry/als h dissolv$1 boil ! solution = #aj-ae m9utes4 ,cov] ! solution ) a wat*-glass2 all[ x to /& until cool1 or pref]ably ov] night4 ,filt] ! solution ?r\gh a lay] ( asbe/os4 ,transf] ! filtrate to a lit] bottle & mix ?or\ghly 7,note #b74 ,note #a3 ,! reactions giv5 on page #fa are ^? :i* take place 9 ! pres5ce ( an excess ( acid4 ,9 neutral solutions ! r$uction ( ! p]manganate is less complete1 &1 "u ^! conditions1 two gram-molecul> weights ( ,k,mn,o#d w furni% only #dh grams ( oxyg54 ,a normal solution = use "u ^! conditions %\ld1 !re=e1 conta9 #caf4j_/f grams1 or #eb4ff grams4 ,note #b3 ,potassium p]manganate solutions are n usually /able = long p]iods1 & *ange m rapidly :5 fir/ prep>$ ?an aft] /&+ "s days4 ,?is *ange is probably caus$ by int]action ) ! organic matt] conta9$ 9 all di/ill$ wat]1 except t r$i/ill$ f an alkal9e p]manganate solution4 ,! solutions %\ld be protect$ f light & heat z f> z possible1 s9ce bo? induce decomposition ) a deposition ( manganese dioxide1 & x has be5 %[n t decomposition proce$s ) consid]able rapidity1 ) ! evolution ( oxyg51 aft] ! dioxide has begun to =m4 ,z comm]cial samples ( ! p]manganate are likely to be contam9at$ by ! dioxide1 x is advisable to boil & filt] solutions ?r\gh asbe/os be=e /&>dization1 z prescrib$ above4 ,su* solutions are relatively /able4 ,,comp>ison ,,( ,,p]manganate ,,& ,,f]r\s ,,solutions ,,proc$ure4--,fill a glass-/opp]$ burette ) ! p]manganate solution1 obs]v+ ! usual precautions1 & fill a second burette ) ! f]r\s sulphate solution prep>$ = use ) ! potassium bi*romate4 ,! p]manganate solution _c be us$ 9 burettes ) rubb] tips1 z a r$uction takes place ^u contact ) ! rubb]4 ,! solution has s deep a color t ! l[] l9e ( ! m5iscus _c be detect$2 read+s mu/ !re=e be made f ! upp] edge4 ,run out into a beak] ab\t #dj cc4 ( ! f]r\s solution1 dilute to ab\t #ajj cc41 add #aj cc4 ( dilute sulphuric acid1 & run 9 ! p]manganate solution to a slight p]man5t p9k4 ,repeat1 until ! ratio ( ! two solutions is satisfactorily e/abli%$4 ,,/&>dization ,,( ,a ,,potassium ,,p]manganate ,,solution 6,selection ( a ,/&>d6 ,comm]cial potassium p]manganate is r>ely suffici5tly pure to admit ( its direct weigh+ z a /&>d4 ,on ?is acc\nt1 & because ( ! unc]ta9ties z to ! p]man5ce ( its solutions1 x is advisable to /&>dize !m aga9/ sub/ances ( kn[n value4 ,^? 9 mo/ common use are iron wire1 f]r\s ammonium sulphate1 sodium oxalate1 oxalic acid1 & "s o!r d]ivatives ( oxalic acid4 ,) ! exception ( sodium oxalate1 ^! all conta9 wat] ( cry/allization :i* may be lo/ on /&+4 ,!y %\ld1 !re=e1 be fre%ly prep>$1 & ) great c>e4 ,at pres5t1 sodium oxalate is consid]$ to be "o ( ! mo/ satisfactory /&>ds4 6,me?od ,a6 6,iron ,/&>ds6 ,! /&>dization processes employ$ :5 iron or its comp\nds are select$ z /&>ds diff] f ^? applicable 9 connection ) oxalate /&>ds4 ,! proc$ure :i* imm$iately foll[s is t 9 use ) iron /&>ds4 ,z 9 ! case ( ! bi*romate process1 x is necess>y to r$uce ! iron completely to ! f]r\s condition be=e titration4 ,! r$uc+ ag5ts available are z9c1 sulphur\s acid1 or sulphuret$ hydrog54 ,/ann\s *loride may also be us$ :5 ! titration is made 9 ! pres5ce ( hydro*loric acid4 ,s9ce ! excess ( bo? ! gase\s r$uc+ ag5ts c only be expell$ by boil+1 ) consequ5t unc]ta9ty reg>d+ bo? ! removal ( ! excess & ! reoxidation ( ! iron1 z9c or /ann\s *lorides are ! mo/ satisfactory ag5ts4 ,= prompt & complete r$uction x is ess5tial t ! iron solution %\ld be br\ght into ultimate contact ) ! z9c4 ,?is is br\ght ab\t by ! use ( a modifi$ ,jones r$uctor1 z %[n 9 ,figure #a4 ,?is r$uctor is a /&>d app>atus & is us$ 9 o!r quantitative processes4 ,illu/ration3 ,fig4 #a ,! tube ,a has an inside diamet] ( #ah mm4 & is #cjj mm4 long2 ! small tube has an inside diamet] ( #f mm4 & ext5ds #ajj mm4 bel[ ! /opcock4 ,at ! base ( ! tube ,a are plac$ "s pieces ( brok5 glass or porcela91 cov]$ by a plug ( glass wool ab\t #h mm4 ?ick1 & ^u ?is is plac$ a ?9 lay] ( asbe/os1 su* z is us$ = ,goo* filt]s1 #a mm4 ?ick4 ,! tube is !n fill$ ) ! amalgamat$ z9c 7,note #a7 to )9 #ej mm4 ( ! top1 & on ! z9c is plac$ a plug ( glass wool4 ,if ! top ( ! tube is n already %ap$ l ! m\? ( a ?i/le-tube 7,b71 a #fj mm4 funnel is fitt$ into ! tube ) a rubb] /opp] & ! r$uctor is connect$ ) a suction bottle1 ,f4 ,! bottle ,d is a safety bottle to prev5t contam9ation ( ! solution by wat] f ! pump4 ,aft] prep>ation = use1 or :5 left /&+1 ! tube ,a %\ld be fill$ ) wat]1 to prev5t clogg+ ( ! z9c4 ,note #a3 ,! use ( f9e z9c 9 ! r$uctor is n necess>y & t5ds to clog ! tube4 ,p>ticles :i* w pass a #aj-me% sieve1 b are reta9$ by "o ( #bj me%es to ! in*1 are mo/ satisfactory4 ,! z9c c be amalgamat$ by /irr+ or %ak+ x 9 a mixture ( #be cc4 ( normal m]curic *loride solution1 #be cc4 ( hydro*loric acid 7sp4 gr4 #a4ab7 & #bej cc4 ( wat] = two m9utes4 ,! solution %\ld !n be p\r$ (f & ! z9c ?or\ghly wa%$4 ,x is !n ready = bottl+ & pres]vation "u wat]4 ,a small quantity ( glass wool is plac$ 9 ! neck ( ! funnel to hold back =eign mat]ial :5 ! r$uctor is 9 use4 ,,/&>dization ,,proc$ure4--,weigh out into ,erl5mey] flasks two portions ( iron wire ( ab\t #j4be gram ea*4 ,dissolve ^! 9 hot dilute sulphuric acid 7#e cc4 ( conc5trat$ acid & #ajj cc4 ( wat]71 us+ a cov]$ flask to avoid loss by spatt]+4 ,boil ! solution = two or ?ree m9utes aft] ! iron has dissolv$ to remove any volatile hydroc>bons4 ,mean:ile prep>e ! r$uctor = use z foll[s3 ,connect ! vacuum bottle ) ! suction pump & p\r into ! funnel at ! top w>m1 dilute sulphuric acid1 prep>$ by add+ #e cc4 ( conc5trat$ sulphuric acid to #ajj cc4 ( di/ill$ wat]4 ,see t ! /opcock 7,c7 is op5 f> en\gh to all[ ! acid to run ?r\gh sl[ly4 ,cont9ue to p\r 9 acid until #bjj cc4 h pass$ ?r\gh1 !n close ! /opcock 6:ile a small quantity ( liquid is /ill left 9 ! funnel64 ,disc>d ! filtrate1 & aga9 pass ?r\gh #ajj cc4 ( ! w>m1 dilute acid4 ,te/ ?is ) ! p]manganate solution4 ,a s+le drop %\ld color x p]man5tly2 if x does n1 repeat ! wa%+1 until assur$ t ! z9c is n contam9at$ ) appreciable quantities ( r$uc+ sub/ances4 ,be sure t no air ent]s ! r$uctor 7,note #a74 ,p\r ! iron solution :ile hot 7b n boil+7 ?r\gh ! r$uctor at a rate n exce$+ #ej cc4 p] m9ute 7,notes #b & #c74 ,wa% out ! beak] ) dilute sulphuric acid1 & foll[ ! iron solution )\t int]ruption ) #age cc4 ( ! w>m acid & f9ally ) #ge cc4 ( di/ill$ wat]1 leav+ ! funnel p>tially fill$4 ,remove ! filt] bottle & cool ! solution quickly "u ! wat] tap 7,note #d71 avoid+ unnecess>y exposure to ! oxyg5 ( ! air4 ,add #aj cc4 ( dilute sulphuric acid & titrate to a fa9t p9k ) ! p]manganate solution1 add+ x directly to ! cont5ts ( ! vacuum flask4 ,%\ld ! end-po9t be ov]/epp$1 ! f]r\s sulphate solution may be add$4 ,f ! volume ( ! solution requir$ to oxidize ! iron 9 ! wire1 calculate ! relation to ! normal ( ! p]manganate solution4 ,! duplicate results %\ld be concordant )9 two p>ts 9 "o ?\s&4 ,note #a3 ,! funnel ( ! r$uctor mu/ nev] be all[$ to empty4 ,if x is left p>tially fill$ ) wat] ! r$uctor is ready = subsequ5t use aft] a v little wa%+2 b a prelim9>y te/ is always necess>y to safegu>d aga9/ error4 ,if m ?an a small drop ( p]manganate solution is requir$ to color #ajj cc4 ( ! dilute acid aft] ! r$uctor is well wa%$1 an all[ance mu/ be made = ! iron 9 ! z9c4 6,great c>e6 mu/ be us$ to prev5t ! access ( air to ! r$uctor aft] x has be5 wa%$ out ready = use4 ,if air ent]s1 hydrog5 p]oxide =ms1 :i* reacts ) ! p]manganate1 & ! results are wor?less4 ,note #b3 ,! iron is r$uc$ to ! f]r\s condition by contact ) ! z9c4 ,! active ag5t may be consid]$ to be 6nasc5t6 hydrog51 & x mu/ be borne 9 m9d t ! visible bubbles are produc$ by molecul> hydrog51 :i* is )\t appreciable effect ^u f]ric iron4 ,! rate at :i* ! iron solution passes ?r\gh ! z9c %\ld n exce$ t prescrib$1 b ! rate may be increas$ some:at :5 ! wa%-wat] is add$4 ,x is well to all[ ! iron solution to run ne>ly1 b n entirely1 out ( ! funnel be=e ! wa%-wat] is add$4 ,if x is necess>y to int]rupt ! process1 ! complete empty+ ( ! funnel c always be avoid$ by clos+ ! /opcock4 ,x is also possible to r$uce ! iron by treatm5t ) z9c 9 a flask f :i* air is exclud$4 ,! z9c mu/ be pres5t 9 excess ( ! quantity necess>y to r$uce ! iron & is f9ally completely dissolv$4 ,?is me?od is1 h[ev]1 less conv5i5t & m t$i\s ?an ! use ( ! r$uctor4 ,note #c3 ,! dilute sulphuric acid = wa%+ mu/ be w>m$ ready = use be=e ! r$uction ( ! iron beg9s1 & x is ( ! fir/ importance t ! volume ( acid & ( wa%-wat] %\ld be measur$1 & ! volume us$ %\ld always be ! same 9 ! /&>dizations & all subsequ5t analyses4 ,note #d3 ,! end-po9t is m p]man5t 9 cold ?an hot solutions1 possibly because ( a slight action ( ! p]manganate ^u ! mangan\s sulphate =m$ dur+ titration4 ,if ! solution turns br[n1 x is an evid5ce ( insuffici5t acid1 & m %\ld be imm$iately add$4 ,! results are likely to be less accurate 9 ?is case1 h[ev]1 z a consequ5ce ( second>y reactions betwe5 ! f]r\s iron & ! manganese dioxide ?r[n d[n4 ,x is wis] to disc>d su* results & repeat ! process4 ,note #e3 ,! potassium p]manganate may1 ( c\rse1 be dilut$ & br\ght to an exactly #j4a ,n solution f ! data "h obta9$4 ,! p]c5tage ( iron 9 ! iron wire mu/ be tak5 into acc\nt 9 all calculations4 6,me?od ,b6 6,oxalate ,/&>ds6 ,,proc$ure4--,weigh out two portions ( pure sodium oxalate ( #j4be-j4c gram ea* into beak]s ( ab\t #fjj cc4 capacity4 ,add ab\t #djj cc4 ( boil+ wat] & #bj cc4 ( mangan\s sulphate solution 7,note #a74 ,:5 ! solution ( ! oxalate is complete1 heat ! liquid1 if necess>y1 until ne> its boil+ po9t 7#gj-ij;,c47 & run 9 ! /&>d p]manganate solution drop by drop f a burette1 /irr+ con/antly until an end-po9t is rea*$ 7,note #b74 ,make a blank te/ ) #bj cc4 ( mangan\s sulphate solution & a volume ( di/ill$ wat] equal to t ( ! titrat$ solution to det]m9e ! volume ( ! p]manganate solution requir$ to produce a v slight p9k4 ,d$uct ?is volume f ! am\nt ( p]manganate solution us$ 9 ! titration4 ,f ! data obta9$1 calculate ! relation ( ! p]manganate solution to ! normal4 ,! reaction involv$ is3 #e,na#b;,c#b,o#d #b,k,mn,o#d #h;,h#b,,s#d -- #e,na#b,,s#d ,k#b,,s#d #b,mn,s,o#d #aj;,,co#b #h;,h#b,o ,note #a3 ,! mangan\s sulphate titrat+ solution is made by dissolv+ #bj grams ( ,mn,s,o#d 9 #bjj cubic c5timet]s ( wat] & add+ #dj cc4 ( conc5trat$ sulphuric acid 7sp4 gr4 #a4hd7 & #dj cc4 or phosphoric acid 7#he74 ,note #b3 ,! reaction betwe5 oxalates & p]manganates takes place quantitatively only 9 hot acid solutions4 ,! temp]atures mu/ n fall bel[ #gj;,c4 ,,det]m9ation ,,( ,,iron ,,9 ,,limonite 6,me?od ,a6 ,! proc$ures1 z "h prescrib$1 are applicable to iron ores 9 g5]al1 provid$ ^! ores conta9 no con/itu5ts :i* are r$uc$ by z9c or /ann\s *loride & reoxidiz$ by p]manganates4 ,_m iron ores conta9 titanium1 & ?is elem5t among o!rs does int]f]e ) ! det]m9ation ( iron by ! process describ$4 ,if1 h[ev]1 ! solutions ( su* ores are treat$ ) sulphuret$ hydrog5 or sulphur\s acid1 in/ead ( z9c or /ann\s *loride to r$uce ! iron1 & ! excess r$uc+ ag5t remov$ by boil+1 an accurate det]m9ation ( ! iron c be made4 ,,proc$ure4--,gr9d ! m9]al to a f9e p[d]4 ,weigh out two portions ( ab\t #j4e gram ea* into small porcela9 crucibles4 ,roa/ ! ore at dull r$ness = t5 m9utes 7,note #a71 all[ ! crucibles to cool1 & place !m & _! cont5ts 9 cass]oles conta9+ #cj cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab74 ,proce$ ) ! solution ( ! ore1 & ! treatm5t ( ! residue1 if necess>y1 exactly z describ$ = ! bi*romate process on page #ef4 ,:5 solution is complete1 add #f cc4 ( conc5trat$ sulphuric acid to ea* cass]ole1 & evaporate on ! /eam ba? until ! solution is ne>ly colorless 7,note #b74 ,cov] ! cass]oles & heat ov] ! flame ( ! burn]1 hold+ ! cass]ole 9 ! h& & rotat+ x sl[ly to ha/5 evaporation & prev5t spatt]+1 until ! heavy :ite fumes ( sulphuric anhydride are freely evolv$ 7,note #c74 ,cool ! cass]oles1 add #ajj cc4 ( wat] 7measur$71 & boil g5tly until ! f]ric sulphate is dissolv$2 p\r ! w>m solution ?r\gh ! r$uctor :i* has be5 previ\sly wa%$2 proce$ z describ$ "u /&>dization1 tak+ pa9s to use ! same volume & /r5g? ( acid & ! same volume ( wa%-wat] z !re prescrib$1 & titrate ) ! p]manganate solution 9 ! r$uctor flask1 us+ ! f]r\s sulphate solution if ! end-po9t %\ld be ov]/epp$4 ,f ! correct$ volume ( p]manganate solution us$1 calculate ! p]c5tage ( iron 7,fe7 9 ! limonite4 ,note #a3 ,! prelim9>y roa/+ is usually necess>y because1 ev5 ?\gh ! sulphuric acid w\ld subsequ5tly *> ! c>bonace\s matt]1 c]ta9 nitrog5\s bodies are n !reby r5d]$ insoluble 9 ! acid1 & w\ld be oxidiz$ by ! p]manganate4 ,note #b3 ,! temp]ature ( ! /eam ba? is n suffici5t to volatilize sulphuric acid4 ,solutions may1 !re=e1 be left to evaporate ov]night )\t dang] ( evaporation to dryness4 ,note #c3 ,! hydro*loric acid1 bo? free & comb9$1 is displac$ by ! less volatile sulphuric acid at its boil+ po9t4 ,f]ric sulphate sep>ates at ?is po9t1 s9ce !re is no wat] to hold x 9 solution & c>e is requir$ to prev5t bump+4 ,! f]ric sulphate usually has a silky appe>ance & is easily di/+ui%$ f ! floccul5t silica :i* (t5 rema9s undissolv$4 6,zimm]mann-,re9h>dt ,proc$ure6 6,me?od 7,b76 ,,proc$ure4--,gr9d ! m9]al to a f9e p[d]4 ,weigh out two portions ( ab\t #j4e gram ea* into small porcela9 crucibles4 ,proce$ ) ! solution ( ! ore1 treat ! residue1 if necess>y1 & r$uce ! iron by ! addition ( /ann\s *loride1 foll[$ by m]curic *loride1 z describ$ = ! bi*romate process on page #ef4 ,dilute ! solution to ab\t #djj cc4 ) cold wat]1 add #aj cc4 ( ! mangan\s sulphate titrat+ solution 7,note #a1 page #fh7 & titrate ) ! /&>d potassium p]manganate solution to a fa9t p9k 7,note #a74 ,f ! /&>dization data already obta9$ calculate ! p]c5tage ( iron 7,fe7 9 ! limonite4 ,note #a3 ,x has already be5 not$ t hydro*loric acid reacts sl[ly 9 cold solutions ) potassium p]manganate4 ,x is1 h[ev]1 possible to obta9 a satisfactory1 al?\gh some:at fugitive end-po9t 9 ! pres5ce ( mangan\s sulphate & phosphoric acid4 ,! explanation ( ! "p play$ by ^! reag5ts is some:at obscure z yet4 ,x is possible t an int]m$iate manganic comp\nd is =m$ :i* reacts rapidly ) ! f]r\s comp\nds--?us 9 effect catalyz+ ! oxidiz+ process4 ,:ile an excess ( hydro*loric acid is necess>y = ! successful r$uction ( ! iron by /ann\s *loride1 too l>ge an am\nt %\ld be avoid$ 9 ord] to less5 ! *ance ( r$uction ( ! p]manganate by ! acid dur+ titration4 ,,det]m9ation ,,( ,,! ,,oxidiz+ ,,p[] ,,( ,,pyrolusite ,,indirect ,,oxidation ,pyrolusite1 :5 pure1 consi/s ( manganese dioxide4 ,its value z an oxidiz+ ag5t1 & = ! production ( *lor9e1 dep5ds ^u ! p]c5tage ( ,mn,o#b 9 ! sample4 ,?is p]c5tage is det]m9$ by an indirect me?od1 9 :i* ! manganese dioxide is r$uc$ & dissolv$ by an excess ( f]r\s sulphate or oxalic acid 9 ! pres5ce ( sulphuric acid1 & ! unus$ excess det]m9$ by titration ) /&>d p]manganate solution4 ,,proc$ure4--,gr9d ! m9]al 9 an agate mort> until no grit :atev] c be detect$ "u ! pe/le 7,note #a74 ,transf] x to a /opp]$ weigh+-tube1 & weigh out two portions ( ab\t #j4e gram into beak]s 7#djj-ejj cc47 ,read ,note #b1 & !n calculate 9 ea* case ! weight ( oxalic acid 7,h#b;,c#b,o#d4b;,h#b,o7 requir$ to react ) ! weights ( pyrolusite tak54 ,! reaction involv$ is ,mn,o#b ,h#b;,c#b,o#d7b;,h#b,o7 ,h#b,,s#d -- ,mn,s,o#d #b;,,co#b #d;,h#b,o4 ,weigh out ab\t #j4b gram 9 excess ( ?is quantity ( 6pure6 oxalic acid into ! correspond+ beak]s1 weigh+ ! acid accurately & record+ ! weight 9 ! notebook4 ,p\r into ea* beak] #be cc4 ( wat] & #ej cc4 ( dilute sulphuric acid 7#a3e71 cov] & w>m ! beak] & its cont5ts g5tly until ! evolution ( c>bon dioxide ceases 7,note #c74 ,if a residue rema9s :i* is suffici5tly color$ to obscure ! end-reaction ( ! p]manganate1 x mu/ be remov$ by filtration4 ,f9ally1 dilute ! solution to #bjj-cjj cc41 heat ! solution to a temp]ature j bel[ boil+1 add #ae cc4 ( a manganese sulphate solution & :ile hot1 titrate = ! excess ( ! oxalic acid ) /&>d p]manganate solution 7,notes #d & #e74 ,f ! correct$ volume ( ! solution requir$1 calculate ! am\nt ( oxalic acid undecompos$ by ! pyrolusite2 subtract ?is f ! total quantity ( acid us$1 & calculate ! weight ( manganese dioxide :i* w\ld react ) ! balance ( ! acid1 & f ?is ! p]c5tage 9 ! sample4 ,note #a3 ,! success ( ! analysis is l>gely dep5d5t ^u ! f95ess ( ! p[d]$ m9]al4 ,if prop]ly gr\nd1 solution %\ld be complete 9 fifte5 m9utes or less4 ,note #b3 ,a mod]ate excess ( oxalic acid above t requir$ to react ) ! pyrolusite is necess>y to promote solution2 o!rwise ! residual quantity ( oxalic acid w\ld be s small t ! la/ p>ticles ( ! m9]al w\ld sc>cely dissolve4 ,x is also desirable t a suffici5t excess ( ! acid %\ld be pres5t to react ) a consid]able volume ( ! p]manganate solution dur+ ! titration1 ?us increas+ ! accuracy ( ! process4 ,on ! o!r h&1 ! excess ( oxalic acid %\ld n be s l>ge z to react ) m ( ! p]manganate solution ?an is conta9$ 9 a #ej cc4 burette4 ,if ! pyrolusite "u exam9ation is kn[n to be ( high grade1 say #hj p] c5t pure1 or above ! calculation ( ! oxalic acid ne$$ may be bas$ ^u an assumption t ! m9]al is all ,mn,o#b4 ,if ! quality ( ! m9]al is unkn[n1 x is bett] to weigh out ?ree portions in/ead ( two & to add to "o ( ^! ! am\nt ( oxalic prescrib$1 assum+ complete purity ( ! m9]al4 ,!n run 9 ! p]manganate solution f a pipette or burette to det]m9e r\ghly ! am\nt requir$4 ,if ! volume exce$s ! cont5ts ( a burette1 ! am\nt ( oxalic acid add$ to ! o!r two portions is r$uc$ accord+ly4 ,note #c3 ,c>e %\ld be tak5 t ! sides ( ! beak] are n ov]heat$1 z oxalic acid w\ld be decompos$ by heat alone if cry/allization %\ld occur on ! sides ( ! vessel4 ,/rong sulphuric acid also decomposes ! oxalic acid4 ,! dilute acid %\ld1 !re=e1 be prep>$ be=e x is p\r$ into ! beak]4 ,note #d3 ,f]r\s ammonium sulphate1 f]r\s sulphate1 or iron wire may be sub/itut$ = ! oxalic acid4 ,! reaction is !n ! foll[+3 #b ,fe,s,o#d ,mn,o#b #b;,h#b,,s#d -- ,fe#b7,,s#d7c #b;,h#b,o ,! excess ( f]r\s iron may also be det]m9$ by titration ) potassium bi*romate1 if desir$4 ,c>e is requir$ to prev5t ! oxidation ( ! iron by ! air1 if f]r\s salts are employ$4 ,note #e3 ,! oxidiz+ p[] ( pyrolusite may be det]m9$ by o!r volumetric processes1 "o ( :i* is outl9$ 9 ! foll[+ reactions3 ,mn,o#b #d;,h,cl -- ,mn,cl#b ,cl#b #b;,h#b,o ,cl#b #b,,ki -- ,i#b #b,k,cl ,i#b #b,na#b,s#b,o#c -- ,na#b,s#d,o#f #b,na,i4 ,! *lor9e g5]at$ by ! pyrolusite is pass$ into a solution ( potassium iodide4 ,! lib]at$ iod9e is !n det]m9$ by titration ) sodium ?iosulphate1 z describ$ on page #gh4 ,?is is a direct process1 al?\gh x involves ?ree /eps4 ,,iodimetry ,! titration ( iod9e aga9/ sodium ?iosulphate1 ) />* z an indicator1 may p]haps be reg>d$ z ! mo/ accurate ( volumetric processes4 ,! ?iosulphate solution may be us$ 9 bo? acid & neutral solutions to measure free iod9e & ! latt] may1 9 turn1 s]ve z a measure ( any sub/ance capable ( lib]at+ iod9e f potassium iodide "u suitable conditions = titration1 z1 = example1 9 ! process outl9$ 9 ,note #e on page #gd4 ,! fundam5tal reaction ^u :i* iodometric processes are bas$ is ! foll[+3 ,i#b #b ,na#b,s#b,o#c -- #b ,na,i ,na#b,s#d,o#f4 ,?is reaction betwe5 iod9e & sodium ?iosulphate1 result+ 9 ! =mation ( ! comp\nd ,na#b,s#d,o#f1 call$ sodium tetra?ionate1 is quantitatively exact1 & diff]s 9 t respect f ! action ( *lor9e or brom9e1 :i* oxidize ! ?iosulphate1 b n quantitatively4 ,,normal ,,solutions ,,( ,,iod9e ,,& ,,sodium ,,?iosulphate ,if ! =mulas ( sodium ?iosulphate & sodium tetra?ionate are writt5 9 a mann] to %[ ! atoms ( oxyg5 associat$ ) sulphur atoms 9 ea*1 ?us1 #b7,na#b74,s#b,o#b & ,na#b,o4,s#d,o#e1 x is pla9 t 9 ! tetra?ionate !re are five atoms ( oxyg5 associat$ ) sulphur1 in/ead ( ! f\r 9 ! two molecules ( ! ?iosulphate tak5 toge!r4 ,al?\gh1 !re=e1 ! iod9e conta9s no oxyg51 ! two atoms ( iod9e h1 9 effect1 br\ght ab\t ! addition ( "o oxyg5 atoms to ! sulphur atoms4 ,t is ! same ?+ z say+ t #bec4hd grams ( iod9e 7,i#b7 are equival5t to #af grams ( oxyg52 h5ce1 s9ce #h grams ( oxyg5 is ! basis ( normal solutions1 #bec4hd_/b or #abf4ig grams ( iod9e %\ld be conta9$ 9 "o lit] ( normal iod9e solution4 ,by a simil> c\rse ( reason+ ! conclusion is rea*$ t ! normal solution ( sodium ?iosulphate %\ld conta91 p] lit]1 its molecul> weight 9 grams4 ,z ! ?iosulphate 9 cry/all9e =m has ! =mula ,na#b,s#b,o#c4e;,h#b,o1 ?is weight is #bdh4ab grams4 ,t5?-normal or hundr$?-normal solutions are g5]ally us$4 ,,prep>ation ,,( ,,/&>d ,,solutions 6,approximate ,/r5g?1 #j4a ,n6 ,,proc$ure4--,weigh out on ! r\gh balances #ac grams ( comm]cial iod9e4 ,place x 9 a mort> ) #ah grams ( potassium iodide & triturate ) small portions ( wat] until all is dissolv$4 ,dilute ! solution to #ajjj cc4 & transf] to a lit] bottle & mix ?or\ghly 7,note #a74a ,footnote #a3 ,x w be f\nd m economical to h a consid]able quantity ( ! solution prep>$ by a laboratory att5dant1 & to h all unus$ solutions return$ to ! common /ock4 ,weigh out #be grams ( sodium ?iosulphate1 dissolve x 9 wat] :i* has be5 previ\sly boil$ & cool$1 & dilute to #ajjj cc41 also ) boil$ wat]4 ,transf] ! solution to a lit] bottle & mix ?or\ghly 7,note #b74 ,note #a3 ,iod9e solutions react ) wat] to =m hydriodic acid "u ! influ5ce ( ! sunlight1 & ev5 at l[ room temp]atures ! iod9e t5ds to volatilize f solution4 ,!y %\ld1 !re=e1 be protect$ f light & heat4 ,iod9e solutions are n /able = long p]iods "u ! be/ ( conditions4 ,!y _c be us$ 9 burettes ) rubb] tips1 s9ce !y attack ! rubb]4 ,note #b3 ,sodium ?iosulphate 7,na#b,s#b,o#c4e;,h#b,o7 is r>ely :olly pure z sold comm]cially1 b may be purifi$ by recry/allization4 ,! c>bon dioxide absorb$ f ! air by di/ill$ wat] decomposes ! salt1 ) ! sep>ation ( sulphur4 ,boil$ wat] :i* has be5 cool$ out ( contact ) ! air %\ld be us$ 9 prep>+ solutions4 ,,indicator ,,solution ,! />* solution = use z an indicator mu/ be fre%ly prep>$4 ,a soluble />* is obta9able :i* s]ves well1 & a solution ( #j4e gram ( ?is />* 9 #be cc4 ( boil+ wat] is suffici5t4 ,! solution %\ld be filt]$ :ile hot & is ready = use :5 cold4 ,if soluble />* is n at h&1 potato />* may be us$4 ,mix ab\t #a gram ) #e cc4 ( cold wat] to a smoo? pa/e1 p\r #aej cc4 ( 6boil+6 wat] ov] x1 w>m = a mom5t on ! hot plate1 & put x aside to settle4 ,decant ! sup]natant liquid ?r\gh a filt] & use ! cle> filtrate2 #e cc4 ( ?is solution are ne$$ = a titration4 ,! solution ( potato />* is less /able ?an ! soluble />*4 ,! solid p>ticles ( ! />*1 if n remov$ by filtration1 become s color$ by ! iod9e t !y are n readily decoloriz$ by ! ?iosulphate 7,note #a74 ,note #a3 ,! blue color :i* results :5 free iod9e & />* are br\ght toge!r is probably n due to ! =mation ( a true *emical comp\nd4 ,x is reg>d$ z a solid solution ( iod9e 9 />*4 ,al?\gh x is un/able1 & easily de/roy$ by heat1 x s]ves z an indicator = ! pres5ce ( free iod9e ( rem>kable s5sitiv5ess1 & makes ! iodometric processes ! mo/ satisfactory ( any 9 ! field ( volumetric analysis4 ,,comp>ison ,,( ,,iod9e ,,& ,,?iosulphate ,,solutions ,,proc$ure4--,place ! solutions 9 burettes 7! iod9e 9 a glass-/opp]$ burette71 obs]v+ ! usual precautions4 ,run out #dj cc4 ( ! ?iosulphate solution into a beak]1 dilute ) #aej cc4 ( wat]1 add #a cc4 to #b cc4 ( ! soluble />* solution1 & titrate ) ! iod9e to ! appe>ance ( ! blue ( ! iodo-/>*4 ,repeat until ! ratio ( ! two solutions is e/abli%$1 rememb]+ all necess>y corrections = burettes & = temp]ature *anges4 ,,/&>dization ,,( ,,solutions ,comm]cial iod9e is usually n suffici5tly pure to p]mit ( its use z a /&>d = ?iosulphate solutions or ! direct prep>ation ( a /&>d solution ( iod9e4 ,x is likely to conta91 beside moi/ure1 "s iod9e *loride1 if *lor9e 0 us$ to lib]ate ! iod9e :5 x 0 prep>$4 ,x may be purifi$ by sublimation aft] mix+ x ) a little potassium iodide1 :i* reacts ) ! iod9e *loride1 =m+ potassium *loride & sett+ free ! iod9e4 ,! sublim$ iod9e is !n dri$ by plac+ x 9 a clos$ conta9] ov] conc5trat$ sulphuric acid4 ,x may !n be weigh$ 9 a /opp]$ weigh+-tube & dissolv$ 9 a solution ( potassium iodide 9 a /opp]$ flask to prev5t loss ( iod9e by volatilization4 ,ab\t #ah grams ( ! iodide & twelve grams ( iod9e p] lit] are requir$ = an approximately t5?-normal solution4 ,an iod9e solution made f comm]cial iod9e may also be /&>diz$ aga9/ ars5i\s oxide 7,z#d,o#f74 ,?is sub/ance also usually requires purification by sublimation be=e use4 ,! sub/ances usually employ$ = ! /&>dization ( a ?iosulphate solution are potassium bromate & metallic copp]4 ,! =m] is obta9able 9 pure condition or may be easily purifi$ by re-cry/allization4 ,copp] wire ( high grade is suffici5tly pure to s]ve z a /&>d4 ,bo? potassium bromate & cupric salts 9 solution w lib]ate iod9e f an iodide1 :i* is !n titrat$ ) ! ?iosulphate solution4 ,! reactions involv$ are ! foll[+3 7a7 ,k,br,o#c #f,,ki #c;,h#b,,s#d -- ,k,br #c;,i#b #c,k#b,,s#d #c;,h#b,o1 7b7 #c;,cu #h;,,hno#c -- #c;,cu7,,no#c7b #b,,no #d;,h#b,o1 #b;,cu7,,no#c7b #d,,ki -- #b;,cu,i #d,,kno#c ,i#b4 ,two me?ods = ! direct /&>dization ( ! sodium ?iosulphate solution are "h describ$1 & "o = ! direct /&>dization ( ! iod9e solution4 6,me?od ,a6 ,,proc$ure4--,weigh out into #ejj cc4 beak]s two portions ( ab\t #j4aej-j4age gram ( potassium bromate4 ,dissolve ea* ( ^! 9 #ej cc4 ( wat]1 & add #aj cc4 ( a potassium iodide solution conta9+ #c grams ( ! salt 9 t volume 7,note #a74 ,add to ! mixture #aj cc4 ( dilute sulphuric acid 7#a volume ( sulphuric acid ) #e volumes ( wat]71 all[ ! solution to /& = ?ree m9utes1 & dilute to #aej cc4 7,note #b74 ,run 9 ?iosulphate solution f a burette until ! color ( ! lib]at$ iod9e is ne>ly de/roy$1 & !n add #a cc4 or #b cc4 ( />* solution1 titrate to ! disappe>ance ( ! iodo-/>* blue1 & f9ally add iod9e solution until ! color is j re/or$4 ,make a blank te/ = ! am\nt ( ?iosulphate solution requir$ to react ) ! iod9e lib]at$ by ! iodate :i* is g5]ally pres5t 9 ! potassium iodide solution1 & d$uct ?is f ! total volume us$ 9 ! titration4 ,f ! data obta9$1 calculate ! relation ( ! ?iosulphate solution to a normal solution1 & subsequ5tly calculate ! simil> value = ! iod9e solution4 ,note #a3--,potassium iodide usually conta9s small am\nts ( potassium iodate z impurity :i*1 :5 ! iodide is br\ght into an acid solution1 lib]ates iod9e1 j z does ! potassium bromate us$ z a /&>d4 ,x is necess>y to det]m9e ! am\nt ( ?iosulphate :i* reacts ) ! iod9e ?us lib]at$ by mak+ a blank te/ ) ! iodide & acid alone4 ,z ! iodate is n always uni=mly di/ribut$ ?r\gh\t ! iodide1 x is bett] to make up a suffici5t volume ( a solution ( ! iodide = ! purposes ( ! "w 9 h&1 & to make ! blank te/ by us+ ! same volume ( ! iodide solution z is add$ 9 ! /&>diz+ process4 ,! iodide solution %\ld conta9 ab\t #c grams ( ! salt 9 #aj cc4 ,note #b3 ,! color ( ! iodo-/>* is some:at less satisfactory 9 conc5trat$ solutions ( ! alkali salts1 notably ! iodides4 ,! dilution prescrib$ obviates ?is difficulty4 6,me?od ,b6 ,,proc$ure4--,weigh out two portions ( #j4be-j4bg gram ( clean copp] wire into #bej cc4 ,erl5mey] flasks 7,note #a74 ,add to ea* #e cc4 ( conc5trat$ nitric acid 7sp4 gr4 #a4db7 & #be cc4 ( wat]1 cov]1 & w>m until solution is complete4 ,add #e cc4 ( brom9e wat] & boil until ! excess ( brom9e is expell$4 ,cool1 & add /rong ammonia 7sp4 gr4 #j4ij7 drop by drop until a deep blue color indicates ! pres5ce ( an excess4 ,boil ! solution until ! deep blue is replac$ by a light blui% gre51 or a br[n /a9 appe>s on ! sides ( ! flask 7,note #b74 ,add #aj cc4 ( /rong acetic acid 7sp4 gr4 #a4jd71 cool "u ! wat] tap1 & add a solution ( potassium iodide 7,note #c7 conta9+ ab\t #c grams ( ! salt1 & titrate ) ?iosulphate solution until ! color ( ! lib]at$ iod9e is ne>ly de/roy$4 ,!n add #a-b cc4 ( fre%ly prep>$ />* solution1 & add ?iosulphate solution1 drop by drop1 until ! blue color is dis*>g$4 ,f ! data obta9$1 includ+ ! blank te/ ( ! iodide1 calculate ! relation ( ! ?iosulphate solution to ! normal4 ,note #a3 ,:ile copp] wire ( comm]ce is n absolutely pure1 ! requirem5ts = its use z a conductor ( electricity are su* t ! impurities con/itute only a few hundr$?s ( "o p] c5t & are negligible = analytical purposes4 ,note #b3 ,ammonia neutralizes ! free nitric acid4 ,x %\ld be add$ 9 slight excess only1 s9ce ! excess mu/ be remov$ by boil+1 :i* is t$i\s4 ,if too mu* ammonia is pres5t :5 acetic acid is add$1 ! result+ ammonium acetate is hydrolyz$1 & ! ammonium hydroxide reacts ) ! iod9e set free4 ,note #c3 ,a consid]able excess ( potassium iodide is necess>y = ! prompt lib]ation ( iod9e4 ,:ile a l>ge excess w d no h>m1 ! co/ ( ?is reag5t is s great t wa/e %\ld be avoid$4 6,me?od ,c6 ,,proc$ure4--,weigh out into #ejj cc4 beak]s two portions ( #j4age-j4bjj gram ea* ( pure ars5i\s oxide4 ,dissolve ea* ( ^! 9 #aj cc4 ( sodium hydroxide solution1 ) /irr+4 ,dilute ! solutions to #aej cc4 & add dilute hydro*loric acid until ! solutions conta9 a few drops 9 excess1 & f9ally add to ea* a conc5trat$ solution ( #e grams ( pure sodium bic>bonate 7,na,h,c,o#c7 9 wat]4 ,cov] ! beak]s be=e add+ ! bic>bonate1 to avoid loss4 ,add ! />* solution & titrate ) ! iod9e to ! appe>ance ( ! blue ( ! iodo-/>*1 tak+ c>e n to pass ! end-po9t by m ?an a few drops 7,note #a74 ,f ! correct$ volume ( ! iod9e solution us$ to oxidize ! ars5i\s oxide1 calculate its relation to ! normal4 ,f ! ratio betwe5 ! solutions1 calculate ! simil> value = ! ?iosulphate solution4 ,note #a3 ,ars5i\s oxide dissolves m readily 9 cau/ic alkali ?an 9 a bic>bonate solution1 b ! pres5ce ( cau/ic alkali dur+ ! titration is n admissible4 ,x is !re=e de/roy$ by ! addition ( acid1 & ! solution is !n made neutral ) ! solution ( bic>bonate1 "p ( :i* reacts ) ! acid1 ! excess rema9+ 9 solution4 ,! reaction dur+ titration is ! foll[+3 ,na#c;,as,o#c ,i#b #b,na,h,c,o#c -- ,na#c;,as,o#d #b,na,i #b;,,co#b ,h#b,o ,z ! reaction betwe5 sodium ?iosulphate & iod9e is n always free f second>y reactions 9 ! pres5ce ( ev5 ! weakly alkal9e bic>bonate1 x is be/ to avoid ! addition ( any consid]able excess ( iod9e4 ,%\ld ! end-po9t be pass$ by a few drops1 ! ?iosulphate may be us$ to correct x4 ,,det]m9ation ,,( ,,copp] ,,9 ,,ores ,copp] ores v>y widely 9 composition f ! ne>ly pure copp] m9]als1 su* z mala*ite & copp] sulphide1 to v l[ grade mat]ials :i* conta9 su* impurities z silica1 lead1 iron1 silv]1 sulphur1 ars5ic1 & antimony4 ,9 ne>ly all v>ieties !re w be f\nd a silice\s residue insoluble 9 acids4 ,! me?od "h giv51 :i* is a modification ( t describ$ by ,a4,h4 ,l[ 76,j4 ,am4 ,*em4 ,soc46 7#aijb71 #bd1 #ajhb71 provides = ! extraction ( ! copp] f commonly occurr+ ores1 & = ! pres5ce ( _! common impurities4 ,= practice analyses x is advisable to select an ore ( a fair degree ( purity4 ,,proc$ure4-- ,weigh out two portions ( ab\t #j4e gram ea* ( ! ore 7:i* %\ld be gr\nd until no grit is detect$7 into #bej cc4 ,erl5mey] flasks or small beak]s4 ,add #aj cc4 ( conc5trat$ nitric acid 7sp4 gr4 #a4db7 & heat v g5tly until ! ore is decompos$ & ! acid evaporat$ ne>ly to dryness 7,note #a74 ,add #e cc4 ( conc5trat$ hydro*loric acid 7sp4 gr4 #a4b7 & w>m g5tly4 ,!n add ab\t #g cc4 ( conc5trat$ sulphuric acid 7sp4 gr4 #a4hd7 & evaporate ov] a free flame until ! sulphuric acid fumes freely 7,note #b74 ,x has !n displac$ nitric & hydro*loric acid f _! comp\nds4 ,cool ! flask or beak]1 add #be cc4 ( wat]1 heat ! solution to boil+1 & boil = two m9utes4 ,filt] to remove insoluble sulphates1 silica & any silv] t may h be5 precipitat$ z silv] *loride1 & receive ! filtrate 9 a small beak]1 wa%+ ! precipitate & filt] pap] ) w>m wat] until ! filtrate & wa%+s am\nt to #ge cc4 ,b5d a /rip ( alum9ium foil 7#e cm4 x #ab cm47 into triangul> =m & place x on edge 9 ! beak]4 ,cov] ! beak] & boil ! solution 7be+ c>eful to avoid loss ( liquid by spatt]+7 = t5 m9utes1 b d n evaporate to small volume4 ,wa% ! cov] glass & sides ( ! beak]4 ,! copp] %\ld n[ be 9 ! =m ( a precipitate at ! bottom ( ! beak] or adh]+ loosely to ! alum9ium %eet4 ,remove ! %eet1 wa% x c>efully ) hydrog5 sulphide wat] & place x 9 a small beak]4 ,decant ! solution ?r\gh a filt]1 wa% ! precipitat$ copp] twice by decantation ) hydrog5 sulphide wat]1 & f9ally transf] ! copp] to ! filt] pap]1 :]e x is aga9 wa%$ ?or\ghly1 be+ c>eful at all times to keep ! precipitat$ copp] cov]$ ) ! wa% wat]4 ,remove & disc>d ! filtrate & place an ,erl5mey] flask "u ! funnel4 ,p\r #ae cc4 ( dilute nitric acid 7sp4 gr4 #a4bj7 ov] ! alum9ium foil 9 ! beak]1 ?us dissolv+ any adh]+ copp]4 ,wa% ! foil ) hot wat] & remove x4 ,w>m ?is nitric acid solution & p\r x sl[ly ?r\gh ! filt] pap]1 !reby dissolv+ ! copp] on ! pap]1 receiv+ ! acid solution 9 ! ,erl5mey] flask4 ,be=e wa%+ ! pap]1 p\r #e cc4 ( saturat$ brom9e wat] 7,note #c7 ?r\gh x & f9ally wa% ! pap] c>efully ) hot wat] & transf] any p>ticles ( copp] :i* may be left on x to ! ,erl5mey] flask4 ,boil to expel ! brom9e4 ,add conc5trat$ ammonia drop by drop until ! appe>ance ( a deep blue coloration indicates an excess4 ,boil until ! deep blue is displac$ by a light blui% gre5 coloration1 or until br[n /a9s =m on ! sides ( ! flask4 ,add #aj cc4 ( /rong acetic acid 7,note #d7 & cool "u ! wat] tap4 ,add a solution conta9+ ab\t #c grams ( potassium iodide1 z 9 ! /&>dization1 & titrate ) ?iosulphate solution until ! yell[ ( ! lib]at$ iod9e is ne>ly dis*>g$4 ,add #a-b cc4 ( fre%ly prep>$ />* solution & titrate to ! disappe>ance ( ! blue color4 ,f ! data obta9$1 calculate ! p]c5tage ( copp] 7,cu7 9 ! ore4 ,note #a3 ,nitric acid1 because ( its oxidiz+ p[]1 is us$ z a solv5t = ! sulphide ores4 ,z a /rong acid x w also dissolve ! copp] f c>bonate ores4 ,! hydro*loric acid is add$ to dissolve oxides ( iron & to precipitate silv] & lead4 ,! sulphuric acid displaces ! o!r acids1 leav+ a solution conta9+ sulphates only4 ,x also1 by its dehydrat+ action1 r5d]s silica f silicates insoluble4 ,note #b3 ,unless prop] precautions are tak5 to insure ! correct conc5trations ( acid ! copp] w n precipitate quantitatively on ! alum9ium foil2 h5ce c>e mu/ be tak5 to foll[ directions c>efully at ?is po9t4 ,lead & silv] h be5 almo/ completely remov$ z sulphate & *loride respectively1 or !y too w\ld be precipitat$ on ! alum9ium4 ,bismu?1 ?\gh precipitat$ on alum9ium1 has no effect on ! analysis4 ,ars5ic & antimony precipitate on alum9ium & w\ld int]f]e ) ! titration if all[$ to rema9 9 ! l[] /ate ( oxidation4 ,note #c3 ,brom9e is add$ to oxidize ars5i\s & antimoni\s comp\nds f ! orig9al sample1 & to oxidize nitr\s acid =m$ by ! action ( nitric acid on copp] & copp] sulphide4 ,note #d3 ,?is reaction c be c>ri$ out 9 ! pres5ce ( sulphuric & hydro*loric acids z well z acetic acid1 b 9 ! pres5ce ( ^! /rong acids ars5ic & antimonic acids may react ) ! hydriodic acid produc$ ) ! lib]ation ( free iod9e1 !reby rev]s+ ! process & introduc+ an error4 ,,det]m9ation ,,( ,,antimony ,,9 ,,/ibnite ,/ibnite is native antimony sulphide4 ,ne>ly pure samples ( ?is m9]al are easily obta9able & %\ld be us$ = practice1 s9ce _m impurities1 notably iron1 s]i\sly int]f]e ) ! accurate det]m9ation ( ! antimony by iodometric me?ods4 ,x is1 moreov]1 ess5tial t ! directions ) respect to am\nts ( reag5ts employ$ & conc5tration ( solutions %\ld be foll[$ closely4 ,,proc$ure4--,gr9d ! m9]al ) great c>e1 & weigh out two portions ( #j4ce-j4dj gram into small1 dry beak]s 7#ajj cc474 ,cov] ! beak]s & p\r ov] ! /ibnite #e cc4 ( conc5trat$ hydro*loric acid 7sp4 gr4 #a4bj7 & w>m g5tly on ! wat] ba? 7,note #a74 ,:5 ! residue is :ite1 add to ea* beak] #b grams ( p[d]$ t>t>ic acid 7,note #b74 ,w>m ! solution on ! wat] ba? = t5 m9utes long]1 dilute ! solution v cauti\sly by add+ wat] 9 portions ( #e cc41 /opp+ if ! solution turns r$4 ,x is possible t no coloration w appe>1 9 :i* case cauti\sly cont9ue ! dilution to #abe cc4 ,if a r$ precipitate or coloration does appe>1 w>m ! solution until x is colorless1 & aga9 dilute cauti\sly to a total volume ( #abe cc4 & boil = a m9ute 7,note #c74 ,if a :ite precipitate ( ! oxy*loride sep>ates dur+ dilution 7:i* %\ld n occur if ! directions are foll[$71 x is be/ to disc>d ! det]m9ation & to />t anew4 ,c>efully neutralize mo/ ( ! acid ) ammonium hydroxide solution 7sp4 gr4 #j4if71 b leave x di/9ctly acid 7,note #d74 ,dissolve #c grams ( sodium bic>bonate 9 #bjj cc4 ( wat] 9 a #ejj cc4 beak]1 & p\r ! cold solution ( ! antimony *loride into ?is1 avoid+ loss by eff]vesc5ce4 ,make sure t ! solution conta9s an excess ( ! bic>bonate1 & !n add #a cc4 or #b cc4 ( />* solution & titrate ) iod9e solution to ! appe>ance ( ! blue1 avoid+ excess 7,notes #e & #f74 ,f ! correct$ volume ( ! iod9e solution requir$ to oxidize ! antimony1 calculate ! p]c5tage ( antimony 7,sb7 9 ! /ibnite4 ,note #a3 ,antimony *loride is volatile ) /eam f its conc5trat$ solutions2 h5ce ^! solutions mu/ n be boil$ until !y h be5 dilut$4 ,note #b3 ,antimony salts1 su* z ! *loride1 are readily hydrolyz$1 & comp\nds su* z ,sb,o,cl are =m$ :i* are (t5 relatively insoluble2 b 9 ! pres5ce ( t>t>ic acid comp\nds ) complex ions are =m$1 & ^! are soluble4 ,an excess ( hydro*loric acid also prev5ts precipitation ( ! oxy*loride because ! ,h ions f ! acid less5 ! dissociation ( ! wat] & ?us prev5t any consid]able hydrolysis4 ,note #c3 ,! action ( hydro*loric acid ^u ! sulphide sets free sulphuret$ hydrog51 a "p ( :i* is held 9 solution by ! acid4 ,?is is usually expell$ by ! heat+ ^u ! wat] ba?2 b if x is n :olly driv5 out1 a po9t is rea*$ dur+ dilution at :i* ! antimony sulphide1 be+ no long] held 9 solution by ! acid1 sep>ates4 ,if ! dilution is imm$iately /opp$ & ! solution w>m$1 ?is sulphide is aga9 br\ght into solution & at ! same "t m ( ! sulphuret$ hydrog5 is expell$4 ,?is proc$ure mu/ be cont9u$ until ! sulphuret$ hydrog5 is all remov$1 s9ce x reacts ) iod9e4 ,if no precipitation ( ! sulphide occurs1 x is an indication t ! sulphuret$ hydrog5 0 all expell$ on solution ( ! /ibnite4 ,note #d3 ,ammonium hydroxide is add$ to neutralize mo/ ( ! acid1 ?us less5+ ! am\nt ( sodium bic>bonate to be add$4 ,! ammonia %\ld n neutralize all ( ! acid4 ,note #e3 ,! reaction :i* takes place dur+ titration may be express$ ?us3 ,na#c,sb,o#c #b,na,h,c,o#c ,i#b -- ,na#c,sb,o#d #b,na,i ,h#b,o #b;,,co#b4 ,note #f3 ,if ! end-po9t is n p]man5t1 t is1 if ! blue ( ! iodo-/>* is dis*>g$ aft] /&+ a few mom5ts1 ! cause may be an insuffici5t quantity ( sodium bic>bonate1 leav+ ! solution slightly acid1 or a v slight precipitation ( an antimony comp\nd :i* is sl[ly act$ ^u by ! iod9e :5 ! latt] is mom5t>ily pres5t 9 excess4 ,9 ei!r case x is bett] to disc>d ! analysis & to repeat ! process1 us+ great] c>e 9 ! am\nts ( reag5ts employ$4 ,,*lorimetry ,! processes includ$ "u ! t]m 6*lorimetry6 comprise ^? employ$ to det]m9e *lor9e1 hypo*lorites1 brom9e1 & hypobromites4 ,! reag5t employ$ is sodium ars5ite 9 ! pres5ce ( sodium bic>bonate4 ,! reaction 9 ! case ( ! hypo*lorites is ,na,cl,o ,na#c;,as,o#c -- ,na#c;,as,o#d ,na,cl4 ,! sodium ars5ite may be prep>$ f pure ars5i\s oxide1 z describ$ bel[1 & is /able = consid]able p]iods2 b comm]cial oxide requires resublimation to remove ars5ic sulphide1 :i* may be pres5t 9 small quantity4 ,to prep>e ! solution1 dissolve ab\t #e grams ( ! p[d]$ oxide1 accurately weigh$1 9 #aj cc4 ( a conc5trat$ sodium hydroxide solution1 dilute ! solution to #cjj cc41 & make x fa9tly acid ) dilute hydro*loric acid4 ,add #cj grams ( sodium bic>bonate dissolv$ 9 a little wat]1 & dilute ! solution to exactly #ajjj cc4 9 a measur+ flask4 ,transf] ! solution to a dry lit] bottle & mix ?or\ghly4 ,x is possible to dissolve ! ars5i\s oxide directly 9 a solution ( sodium bic>bonate1 ) g5tle w>m+1 b solution 9 sodium hydroxide takes place mu* m rapidly1 & ! excess ( ! hydroxide is readily neutraliz$ by hydro*loric acid1 ) subsequ5t addition ( ! bic>bonate to ma9ta9 neutrality dur+ ! titration4 ,! indicator requir$ = ?is process is made by dipp+ /rips ( filt] pap] 9 a />* solution prep>$ z describ$ on page #gf1 to :i* #a gram ( potassium iodide has be5 add$4 ,^! /rips are all[$ to dra9 & spread ^u a wat*-glass until dry4 ,:5 t\*$ by a drop ( ! solution ! pap] turns blue until ! hypo*lorite has all be5 r$uc$ & an excess ( ! ars5ite has be5 add$4 ,,det]m9ation ,,( ,,! ,,available ,,*lor9e ,,9 ,,blea*+ ,,p[d] ,blea*+ p[d] consi/s ma9ly ( a calcium comp\nd :i* is a d]ivative ( bo? hydro*loric & hypo*lor\s acids4 ,its =mula is ,ca,cl,o,cl4 ,its use z a blea*+ or dis9fect+ ag5t1 or z a s\rce ( *lor9e1 dep5ds ^u ! am\nt ( hypo*lor\s acid :i* x yields :5 treat$ ) a /rong] acid4 ,x is cu/om>y to express ! value ( blea*+ p[d] 9 t]ms ( available *lor9e1 by :i* is meant ! *lor9e pres5t z hypo*lorite1 b n ! *lor9e pres5t z *loride4 ,,proc$ure4--,weigh out f a /opp]$ te/ tube into a porcela9 mort> ab\t #c4e grams ( blea*+ p[d] 7,note #a74 ,triturate ! p[d] 9 ! mort> ) successive portions ( wat] until x is well gr\nd & wa% ! cont5ts into a #ejj cc4 measur+ flask 7,note #b74 ,fill ! flask to ! m>k ) wat] & %ake ?or\ghly4 ,measure (f #be cc4 ( ?is semi-solution 9 a measur+ flask1 or pipette1 obs]v+ ! precaution t ! liquid remov$ %all conta9 approximately its proportion ( susp5d$ matt]4 ,empty ! flask or pipette into a beak] & wa% x out4 ,run 9 ! ars5ite solution f a burette until no fur!r reaction takes place on ! />*-iodide pap] :5 t\*$ by a drop ( ! solution ( blea*+ p[d]4 ,repeat ! titration1 us+ a second #be cc4 portion4 ,f ! volume ( solution requir$ to react ) ! blea*+ p[d]1 calculate ! p]c5tage ( available *lor9e 9 ! latt]1 assum+ ! titration reaction to be t betwe5 *lor9e & ars5i\s oxide3 ,z#d,o#f #d;,cl#b #d;,h#b,o -- #b;,z#b,o#e #h;,h,cl ,note t only "o tw5tie? ( ! orig9al weight ( blea*+ p[d] ent]s into ! reaction4 ,note #a3 ,! p[d] mu/ be triturat$ until x is f9e1 o!rwise ! lumps w inclose calcium hypo*lorite1 :i* w fail to react ) ! ars5i\s acid4 ,! cle> sup]natant liquid gives p]c5tages :i* are bel[1 & ! s$im5t p]c5tages :i* are above1 ! av]age4 ,! liquid measur$ (f %\ld1 !re=e1 c>ry ) x its prop] proportion ( ! s$im5t1 s f> z t c be br\ght ab\t by %ak+ ! solution j be=e removal ( ! aliquot "p = titration4 ,note #b3 ,blea*+ p[d] is easily act$ ^u by ! c>bonic acid 9 ! air1 :i* lib]ates ! weak hypo*lor\s acid4 ,?is1 ( c\rse1 results 9 a loss ( available *lor9e4 ,! orig9al mat]ial = analysis %\ld be kept 9 a clos$ conta9] & protect$ =m ! air z f> z possible4 ,x is difficult to obta9 analytical samples :i* are accurately repres5tative ( a l>ge quantity ( ! blea*+ p[d]4 ,! proc$ure1 z outl9$1 w yield results :i* are suffici5tly exact = te*nical purposes4 ,,iii4 ,,precipitation ,,me?ods ,,det]m9ation ,,( ,,silv] ,,by ,,! ,,?iocyanate ,,process ,! addition ( a solution ( potassium or ammonium ?iocyanate to "o ( silv] 9 nitric acid causes a deposition ( silv] ?iocyanate z a :ite1 curdy precipitate4 ,if f]ric nitrate is also pres5t1 ! slighte/ excess ( ! ?iocyanate ov] t requir$ to comb9e ) ! silv] is indicat$ by ! deep r$ :i* is *>act]i/ic ( ! ?iocyanate te/ = iron4 ,! reactions involv$ are3 ,ag,n,o#c ,,kscn -- ,ag,s,c,n ,,kno#c1 #c,,kscn ,fe7,,no#c7c -- ,fe7,,scn7#c #c,,kno#c4 ,! f]ric ?iocyanate diff]s f ! great majority ( salts 9 t x is b v little dissociat$ 9 aque\s solutions1 & ! *>act]i/ic color appe>s to be occasion$ by ! =mation ( ! un-ioniz$ f]ric salt4 ,! normal solution ( potassium ?iocyanate %\ld conta9 an am\nt ( ! salt p] lit] ( solution :i* w\ld yield suffici5t 7,,cns7- to comb9e ) "o gram ( hydrog5 to =m ,,hcns1 i4e41 a gram-molecul> weight ( ! salt or #ig4ag grams4 ,if ! ammonium ?iocyanate is us$1 ! am\nt is #gf4jh grams4 ,to prep>e ! solution = ?is det]m9ation1 :i* %\ld be approximately #j4je ,n1 dissolve ab\t #e grams ( potassium ?iocyanate1 or #d grams ( ammonium ?iocyanate1 9 a small am\nt ( wat]2 dilute ?is solution to #ajjj cc4 9 a lit] bottle & mix z usual4 ,prep>e #bj cc4 ( a saturat$ solution ( f]ric alum & add #e cc4 ( dilute nitric acid 7sp4 gr4 #a4bj74 ,ab\t #e cc4 ( ?is solution %\ld be us$ z an indicator4 ,,/&>dization ,,proc$ure4--,cru% a small quantity ( silv] nitrate cry/als 9 a mort> 7,note #a74 ,transf] !m to a wat*-glass & dry !m = an h\r at #aaj;,c41 protect+ !m f du/ or o!r organic matt] 7,note #b74 ,weigh out two portions ( ab\t #j4e gram ea* & dissolve !m 9 #ej cc4 ( wat]4 ,add #aj cc4 ( dilute nitric acid :i* has be5 rec5tly boil$ to expel ! l[] oxides ( nitrog51 if any1 & !n add #e cc4 ( ! indicator solution4 ,run 9 ! ?iocyanate solution f a burette1 ) con/ant /irr+1 all[+ ! precipitate to settle occasionally to obta9 an exact recognition ( ! end-po9t1 until a fa9t r$ t+e c be detect$ 9 ! solution4 ,f ! data obta9$1 calculate ! relation ( ! ?iocyanate solution to ! normal4 ,note #a3 ,! ?iocyanate _c be accurately weigh$2 its solutions mu/1 !re=e1 be /&>diz$ aga9/ silv] nitrate 7or pure silv]71 ei!r 9 ! =m ( a /&>d solution or 9 small1 weigh$ portions4 ,note #b3 ,! cry/als ( silv] nitrate sometimes inclose wat] :i* is expell$ on dry+4 ,if ! nitrate has come into contact ) organic bodies x suff]s a r$uction & black5s dur+ ! heat+4 ,x is pla9 t a /&>d solution ( silv] nitrate 7made by weigh+ out ! cry/als7 is conv5i5t or necess>y if _m titrations ( ?is nature are to be made4 ,9 ! abs5ce ( su* a solution ! liability ( pass+ ! end-po9t is less5$ by sett+ aside a small fraction ( ! silv] solution1 to be add$ ne> ! close ( ! titration4 ,,det]m9ation ,,( ,,silv] ,,9 ,,co9 ,,proc$ure4-- ,weigh out two portions ( ! co9 ( ab\t #j4e gram ea*4 ,dissolve !m 9 #ae cc4 ( dilute nitric acid 7sp4 gr4 #a4b7 & boil until all ! nitr\s comp\nds are expell$ 7,note #a74 ,cool ! solution1 dilute to #ej cc41 & add #e cc4 ( ! indicator solution1 & titrate ) ! ?iocyanate to ! appe>ance ( ! fa9t r$ coloration 7,note #b74 ,f ! correct$ volume ( ! ?iocyanate solution requir$1 calculate ! p]c5tage ( silv] 9 ! co94 ,note #a3 ,! reaction ) silv] may be c>ri$ out 9 nitric acid solutions & 9 ! pres5ce ( copp]1 if ! latt] does n exce$ #gj p] c5t4 ,above t p]c5tage x is necess>y to add silv] 9 kn[n quantity to ! solution4 ,! liquid mu/ be cold at ! "t ( titration & entirely free f nitr\s comp\nds1 z ^! sometimes cause a r$d5+ ( ! indicator solution4 ,all ut5sils1 di/ill$ wat]1 ! nitric acid & ! beak]s mu/ be free f *lorides1 z ! pres5ce ( ^! w cause precipitation ( silv] *loride1 !reby introduc+ an error4 ,note #b3 ,! solution conta9+ ! silv] precipitate1 z well z ^? f ! /&>dization1 %\ld be plac$ 9 ! receptacle = silv] residues z a matt] ( economy4 ,,"p ,,iii ,,gravimetric ,,analysis ,,g5]al ,,directions ,gravimetric analyses involve ! foll[+ pr9cipal /eps3 fir/1 ! weigh+ ( ! sample2 second1 ! solution ( ! sample2 ?ird1 ! sep>ation ( "s sub/ance f solution conta9+1 or be>+ a def9ite relation to1 ! con/itu5t to be measur$1 "u conditions :i* r5d] ?is sep>ation z complete z possible2 & f9ally1 ! segregation ( t sub/ance1 commonly by filtration1 & ! det]m9ation ( its weight1 or t ( "s /able product =m$ f x on ignition4 ,= example1 ! gravimetric det]m9ation ( alum9ium is accompli%$ by solution ( ! sample1 by precipitation 9 ! =m ( hydroxide1 collection ( ! hydroxide ^u a filt]1 complete removal by wa%+ ( all =eign soluble matt]1 & ! burn+ ( ! filt] & ignition ( ! precipitate to alum9ium oxide1 9 :i* condition x is weigh$4 ,among ! op]ations :i* are common to ne>ly all gravimetric analyses are precipitation1 wa%+ ( precipitates1 ignition ( precipitates1 & ! use ( desiccators4 ,9 ord] to avoid burd5some repetitions 9 ! descriptions ( ! v>i\s gravimetric proc$ures :i* foll[1 c]ta9 g5]al in/ructions are introduc$ at ?is po9t4 ,^! in/ructions mu/1 !re=e1 be consid]$ to be z mu* a "p ( all subsequ5t proc$ures z ! description ( app>atus1 reag5ts1 or manipulations4 ,! analytical balance1 ! fundam5tally important in/rum5t 9 gravimetric analysis1 has already be5 describ$ on pages #aa to #ae4 ,,precipitation ,= successful quantitative precipitations ^? sub/ances are select$ :i* are lea/ soluble "u conditions :i* c be easily e/abli%$1 & :i* sep>ate f solution 9 su* a /ate t !y c be filt]$ readily & wa%$ free f admix$ mat]ial4 ,9 g5]al1 ! sub/ances select$ are ! same z ^? already famili> to ! /ud5t ( ,qualitative ,analysis4 ,:5 possible1 sub/ances are select$ :i* sep>ate 9 cry/all9e =m1 s9ce su* sub/ances are less likely to clog ! pores ( filt] pap] & c be mo/ quickly wa%$4 ,9 ord] to increase ! size ( ! cry/als1 :i* fur!r promotes filtration & wa%+1 x is (t5 desirable to all[ a precipitate to rema9 = "s "t 9 contact ) ! solution f :i* x has sep>at$4 ,! solution is (t5 kept w>m dur+ ?is p]iod ( dige/ion4 ,! small cry/als gradually disappe> & ! l>g] cry/als increase 9 size1 probably z ! result ( ! =ce kn[n z surface t5sion1 :i* t5ds to r$uce ! surface ( a giv5 mass ( mat]ial to a m9imum1 comb9$ ) a v slightly great] solubility ( small cry/als z comp>$ ) ! l>g] ones4 ,amorph\s sub/ances1 su* z f]ric hydroxide1 alum9ium hydroxide1 or silicic acid1 sep>ate 9 a gelat9\s =m & are relatively difficult to filt] & wa%4 ,sub/ances ( ?is class also exhibit a t5d5cy to =m1 ) pure wat]1 :at are kn[n z colloidal solutions4 ,to prev5t ?is z f> z possible1 !y are wa%$ ) solutions ( volatile salts1 z w be describ$ 9 "s ( ! foll[+ proc$ures4 ,9 all precipitations ! reag5t %\ld be add$ sl[ly1 ) con/ant /irr+1 & %\ld be hot :5 circum/ances p]mit4 ,! sl[ addition is less likely to occasion contam9ation ( ! precipitate by ! inclosure ( o!r sub/ances :i* may be 9 ! solution1 or ( ! reag5t itself4 ,,funnels ,,& ,,filt]s ,filtration 9 analytical processes is mo/ commonly effect$ ?r\gh pap] filt]s4 ,9 special cases ^! may be advantage\sly replac$ by an asbe/os filt] 9 a p]=at$ porcela9 or plat9um crucible1 commonly kn[n1 f its orig9ator1 z a ,goo* filt]4 ,! op]ation & use ( a filt] ( ?is type is describ$ on page #ajc4 ,por\s crucibles ( a mat]ial kn[n z alundum may also be employ$ to advantage 9 special cases4 ,! glass funnels select$ = use ) pap] filt]s %\ld h an angle z ne> #fj z possible1 & a n>r[ /em ab\t six in*es 9 l5g?4 ,! filt]s employ$ %\ld be wa%$ filt]s1 i4e41 ^? :i* h be5 treat$ ) hydro*loric & hydr(luoric acids1 & :i* on inc9]ation leave a v small & def9itely kn[n weight ( a%1 g5]ally ab\t 4#jjjjc gram4 ,su* filt]s are readily obta9able on ! m>ket4 ,! filt] %\ld be c>efully fold$ to fit ! funnel accord+ to ei!r ( ! two well-e/abli%$ me?ods describ$ 9 ! ,app5dix4 ,x %\ld always be plac$ s t ! upp] edge ( ! pap] is ab\t "o f\r? in* bel[ ! top ( ! funnel4 ,"u no circum/ances %\ld ! filt] ext5d above ! edge ( ! funnel1 z x is !n utt]ly impossible to effect complete wa%+4 ,to te/ ! effici5cy ( ! filt]1 fill x ) di/ill$ wat]4 ,?is wat] %\ld soon fill ! /em completely1 =m+ a cont9u\s column ( liquid :i*1 by its hydro/atic pressure1 produces a g5tle suction1 ?us mat]ially promot+ ! rapidity ( filtration4 ,unless ! filt] all[s free passage ( wat] "u ^! conditions1 x is likely to give mu* tr\ble :5 a precipitate is plac$ ^u x4 ,! use ( a suction pump to promote filtration is r>ely altoge!r advantage\s 9 quantitative analysis1 if pap] filt]s are employ$4 ,! t5d5cy ( ! filt] to break1 unless ! po9t ( ! filt] pap] is support$ by a p]=at$ porcela9 cone or a small h>d5$ filt] ( p>*m5t1 & ! t5d5cy ( ! precipitates to pass ?r\gh ! pores ( ! filt]1 m ?an comp5sate = ! possible ga9 9 "t4 ,on ! o!r h&1 filtration by suction may be useful 9 ! case ( precipitates :i* d n require ignition be=e weigh+1 or 9 ! case ( precipitates :i* are to be disc>d$ )\t weigh+4 ,?is is be/ accompli%$ ) ! aid ( ! special app>atus call$ a ,goo* filt] ref]r$ to above4 ,,filtration ,,& ,,wa%+ ,,( ,,precipitates ,solutions %\ld be filt]$ :ile hot1 z f> z possible1 s9ce ! passage ( a liquid ?r\gh ! pores ( a filt] is ret>d$ by friction1 & ?is1 = wat] at #ajj;,c41 is less ?an "o six? ( ! resi/ance at #j;,c4 ,:5 ! filtrate is receiv$ 9 a beak]1 ! /em ( ! funnel %\ld t\* ! side ( ! receiv+ vessel to avoid loss by spatt]+4 ,neglect ( ?is precaution is a frequ5t s\rce ( error4 ,! vessels :i* conta9 ! initial filtrate %\ld 6always6 be replac$ by clean ones1 prop]ly label$1 be=e ! wa%+ ( a precipitate beg9s4 ,9 _m in/ances a f9ely divid$ precipitate :i* %[s no t5d5cy to pass ?r\gh ! filt] at fir/1 :ile ! solution is relatively d5se1 appe>s at once 9 ! wa%+s4 ,"u su* conditions ! advantages accru+ f ! removal ( ! fir/ filtrate are obvi\s1 bo? z reg>ds ! dim9i%$ volume requir+ refiltration1 & also ! small] numb] ( wa%+s subsequ5tly requir$4 ,mu* "t may (t5 be sav$ by wa%+ precipitates by decantation1 i4e41 by p\r+ ov] !m1 :ile /ill 9 ! orig9al vessel1 consid]able volumes ( wa%-wat] & all[+ !m to settle4 ,! sup]natant1 cle> wa%-wat] is !n decant$ ?r\gh ! filt]1 s f> z practicable )\t di/urb+ ! precipitate1 & a new portion ( wa%-wat] is add$4 ,?is proc$ure c be employ$ to special advantage ) gelat9\s precipitates1 :i* fill up ! pores ( ! filt] pap]4 ,z ! m$ium f :i* ! precipitate is to settle becomes less d5se x subsides less readily1 & x ultimately becomes necess>y to transf] x to ! filt] & complete ! wa%+ !re4 ,a precipitate %\ld nev] completely fill a filt]4 ,! wa%-wat] %\ld be appli$ at ! top ( ! filt]1 above ! precipitate4 ,x may be %[n ma!matically t ! wa%+ is mo/ 6rapidly6 accompli%$ by fill+ ! filt] well to ! top ) wa%-wat] ea* "t1 & all[+ x to dra9 completely aft] ea* addition2 b t :5 a precipitate is to be wa%$ ) ! 6lea/ possible volume6 ( liquid ! latt] %\ld be appli$ 9 repeat$ 6small6 quantities4 ,gelat9\s precipitates %\ld n be all[$ to dry be=e complete removal ( =eign matt] is effect$4 ,!y are likely to %r9k & crack1 & subsequ5t additions ( wa%-wat] pass ?r\gh ^! *annels only4 ,all filtrates & wa%-wat]s )\t exception mu/ be prop]ly te/$4 6,?is lies at ! f\ndation ( accurate "w61 & ! /ud5t %\ld cle>ly und]/& t x is only by ! inv>iable application ( ?is rule t assurance ( ultimate reliability c be secur$4 ,e orig9al filtrate mu/ be te/$ to prove complete precipitation ( ! comp\nd to be sep>at$1 & ! wa%-wat]s mu/ also be te/$ to assure complete removal ( =eign mat]ial4 ,9 te/+ ! latt]1 ! am\nt fir/ tak5 %\ld be b a few drops if ! filtrate conta9s mat]ial :i* is to be subsequ5tly det]m9$4 ,:51 h[ev]1 ! wa%+ ( ! filt] & precipitate is ne>ly complet$ ! am\nt %\ld be increas$1 & = ! f9al te/ n less ?an #c cc4 %\ld be us$4 ,x is impossible to tru/ to "o's judgm5t ) reg>d to ! wa%+ ( precipitates2 ! wa%+s f 6ea* precipitate6 ( a s]ies simultane\sly treat$ mu/ be te/$1 s9ce ! rate ( wa%+ w (t5 diff] mat]ially "u app>5tly simil> conditions1 6,no exception c ev] be made to ?is rule64 ,! habit ( plac+ a clean common filt] pap] "u ! receiv+ beak] dur+ filtration is "o to be comm5d$4 ,on ?is pap] a record ( ! numb] ( wa%+s c v well be made z ! portions ( wa%-wat] are add$4 ,x is an excell5t practice1 :5 possible1 to reta9 filtrates & precipitates until ! completion ( an analysis1 9 ord] t1 9 case ( "q1 !y may be exam9$ to discov] s\rces ( error4 ,= ! complete removal ( precipitates f conta9+ vessels1 x is (t5 necess>y to rub ! sides ( ^! vessels to loos5 ! adh]+ p>ticles4 ,?is c be/ be done by slipp+ ov] ! end ( a /irr+ rod a s(t rubb] device sometimes call$ a policeman4 ,,desiccators ,desiccators %\ld be fill$ ) fus$1 anhydr\s calcium *loride1 ov] :i* is plac$ a clay triangle1 or an iron triangle cov]$ ) silica tubes1 to support ! crucible or o!r ut5sils4 ,! cov] ( ! desiccator %\ld be made air-tight by ! use ( a ?9 coat+ ( vasel9e4 ,pumice moi/5$ ) conc5trat$ sulphuric acid may be us$ 9 place ( ! calcium *loride1 & is ess5tial 9 special cases2 b = mo/ purposes ! calcium *loride1 if r5ew$ occasionally & n all[$ to cake toge!r1 is practically effici5t & does n slop ab\t :5 ! desiccator is mov$4 ,desiccators %\ld nev] rema9 uncov]$ = any l5g? ( "t4 ,! dehydrat+ ag5ts rapidly lose _! effici5cy on exposure to ! air4 ,,crucibles ,x is (t5 necess>y 9 quantitative analysis to employ fluxes to br+ into solution sub/ances :i* are n dissolv$ by acids4 ,! fluxes 9 mo/ common use are sodium c>bonate & sodium or potassium acid sulphate4 ,9 gravimetric analysis x is usually necess>y to ignite ! sep>at$ sub/ance aft] filtration & wa%+1 9 ord] to remove moi/ure1 or to conv]t x ?r\gh physical or *emical *anges into "s def9ite & /able =m = weigh+4 ,crucibles to be us$ 9 fusion processes mu/ be made ( mat]ials :i* w )/& ! action ( ! fluxes employ$1 & crucibles to be us$ = ignitions mu/ be made ( mat]ial :i* w n und]go any p]man5t *ange dur+ ! ignition1 s9ce ! initial weight ( ! crucible mu/ be d$uct$ f ! f9al weight ( ! crucible & product to obta9 ! weight ( ! ignit$ sub/ance4 ,! ?ree mat]ials :i* satisfy ^! conditions1 9 g5]al1 are plat9um1 porcela91 & silica4 ,plat9um crucibles h ! advantage t !y c be employ$ at high temp]atures1 b1 on ! o!r h&1 ^! crucibles c nev] be us$ :5 !re is a possibility ( ! r$uction to ! metallic /ate ( metals l lead1 copp]1 silv]1 or gold1 :i* w\ld alloy ) & ru9 ! crucible4 ,:5 plat9um crucibles are us$ ) comp\nds ( ars5ic or phosphorus1 special precautions are necess>y to prev5t damage4 ,?is /atem5t applies to bo? fusions & ignitions4 ,fusions ) sodium c>bonate c be made only 9 plat9um1 s9ce porcela9 or silica crucibles are attack$ by ?is reag5t4 ,acid sulphate fusions1 :i* require comp>atively l[ temp]atures1 c sometimes be made 9 plat9um1 al?\gh plat9um is slightly attack$ by ! flux4 ,porcela9 or silica crucibles may be us$ ) acid fluxes4 ,silica crucibles are less likely to crack on heat+ ?an porcela9 crucibles on acc\nt ( _! small] coeffici5t ( expansion4 ,ignition ( sub/ances n requir+ too high a temp]ature may be made 9 porcela9 or silica crucibles4 ,iron1 nickel or silv] crucibles are us$ 9 special cases4 ,9 g5]al1 plat9um crucibles %\ld be us$ :5ev] su* use is practicable1 & ?is is ! cu/om 9 private1 rese>* or comm]cial laboratories4 ,plat9um has1 h[ev]1 become s valuable t x is liable to !ft unless con/antly "u ! protection ( ! us]4 ,z con/ant protection is (t5 difficult 9 in/ructional laboratories1 x is advisable1 9 ord] to avoid s]i\s monet>y losses1 to use porcela9 or silica crucibles :5ev] ^! w give satisfactory s]vice4 ,:5 plat9um ut5sils are us$ ! dang] ( !ft %\ld always be kept 9 m9d4 ,,prep>ation ,,( ,,crucibles ,,= ,,use ,all crucibles1 ( :atev] mat]ial1 mu/ always be clean$1 ignit$ & all[$ to cool 9 a desiccator be=e weigh+1 s9ce all bodies expos$ to ! air cond5se on _! surfaces a lay] ( moi/ure :i* increases _! weight4 ,! am\nt & weight ( ?is moi/ure v>ies ) ! humidity ( ! atmosph]e1 & ! latt] may *ange f h\r to h\r4 ,! air 9 ! desiccator 7see above7 is kept at a con/ant & l[ humidity by ! dry+ ag5t :i* x conta9s4 ,bodies :i* rema9 9 a desiccator = a suffici5t "t 7usually #bj-cj m9utes7 reta91 !re=e1 on _! surfaces a con/ant weight ( moi/ure :i* is ! same day aft] day1 ?us insur+ con/ant conditions4 ,hot objects1 su* z ignit$ crucibles1 %\ld be all[$ to cool 9 ! air until1 :5 held ne> ! sk91 b little heat is noticeable4 ,if ?is precaution is n tak51 ! air )9 ! desiccator is /rongly heat$ & exp&s be=e ! desiccator is cov]$4 ,z ! temp]ature falls1 ! air contracts1 caus+ a r$uction ( air pressure )9 ! cov]$ vessel4 ,:5 ! cov] is remov$ 7:i* is (t5 r5d]$ difficult7 ! inru% ( air f ! outside may sweep light p>ticles out ( a crucible1 ?us ru9+ an entire analysis4 ,con/ant heat+ ( plat9um causes a slight cry/allization ( ! surface :i*1 if n remov$1 p5etrates into ! crucible4 ,g5tle poli%+ ( ! surface de/roys ! cry/all9e /ructure & prev5ts fur!r damage4 ,if sea s& is us$ = ?is purpose1 great c>e is necess>y to keep x f ! desk1 s9ce beak]s are easily scrat*$ by x1 & subsequ5tly crack on heat+4 ,plat9um crucibles /a9$ 9 use may (t5 be clean$ by ! fusion 9 !m ( potassium or sodium acid sulphate1 or by heat+ ) ammonium *loride4 ,if ! =m] is us$1 c>e %\ld be tak5 n to heat s /rongly z to expel all ( ! sulphuric acid1 s9ce ! normal sulphates sometimes exp& s rapidly on cool+ z to split ! crucible4 ,! fus$ mat]ial %\ld be p\r$ out1 :ile hot1 on to a 6dry6 tile or iron surface4 ,,ignition ,,( ,,precipitates ,mo/ precipitates may1 if prop] precautions are tak51 be ignit$ )\t previ\s dry+4 ,if1 h[ev]1 su* precipitates c be dri$ )\t loss ( "t to ! analy/ 7z1 = example1 ov] night71 x is well to submit !m to ?is process4 ,x %\ld1 nev]!less1 be rememb]$ t a p>tially dri$ precipitate (t5 requires m c>e dur+ ignition ?an a ?or\ghly moi/ "o4 ,! details ( ! ignition ( precipitates v>y s mu* ) ! "* ( ! precipitate1 its moi/ure cont5t1 & temp]ature to :i* x is to be heat$1 t ^! details w be giv5 "u ! v>i\s proc$ures :i* foll[4 ,,det]m9ation ,,( ,,*lor9e ,,9 ,,sodium ,,*loride 6,me?od ,a4 ,) ! ,use ( a ,goo* ,filt]6 ,,proc$ure4--,c>efully clean a weigh+-tube conta9+ ! sodium *loride1 h&l+ x z little z possible ) ! moi/ f+]s1 & weigh x accurately to #j4jjja gram1 record+ ! weight at once 9 ! notebook 7see ,app5dix74 ,hold ! tube ov] ! top ( a beak] 7#bjj-cjj cc471 & cauti\sly remove ! /opp]1 not+ c>efully t no p>ticles fall f x1 or f ! tube1 else:]e ?an into ! beak]4 ,p\r out a small portion ( ! *loride1 replace ! /opp]1 & det]m9e by approximate weigh+ h[ mu* has be5 remov$4 ,cont9ue ?is proc$ure until #j4be-j4cj gram has be5 tak5 f ! tube1 !n weigh accurately & record ! weight b5ea? ! fir/ 9 ! notebook4 ,! diff]5ce ( ! two weights repres5ts ! weight ( ! *loride tak5 = analysis4 ,aga9 weigh a second portion ( #j4be-j4cj gram into a second beak] ( ! same size z ! fir/4 ,! beak]s %\ld be pla9ly m>k$ to correspond ) ! entries 9 ! notebook4 ,dissolve ea* portion ( ! *loride 9 #aej cc4 ( di/ill$ wat] & add ab\t t5 drops ( dilute nitric acid 7sp4 gr4 #a4bj7 7,note #b74 ,calculate ! volume ( silv] nitrate solution requir$ to effect complete precipitation 9 ea* case1 & add sl[ly ab\t #e cc4 9 excess ( t am\nt1 ) con/ant /irr+4 ,heat ! solutions cauti\sly to boil+1 /irr+ occasionally1 & cont9ue ! heat+ & /irr+ until ! precipitates settle promptly1 leav+ a ne>ly cle> sup]natant liquid 7,note #c74 ,?is heat+ %\ld n take place 9 direct sunlight 7,note #d74 ,! beak] %\ld be cov]$ ) a wat*-glass1 & bo? boil+ & /irr+ s regulat$ z to preclude any possibility ( loss ( mat]ial4 ,add to ! cle> liquid "o or two drops ( silv] nitrate solution1 to make sure t an excess ( ! reag5t is pres5t4 ,if a precipitate1 or cl\d9ess1 appe>s z ! drops fall into ! solution1 heat aga91 & /ir until ! :ole precipitate has coagulat$4 ,! solution is !n ready = filtration4 ,prep>e a ,goo* filt] z foll[s3 ,fold ov] ! top ( a ,goo* funnel 7,fig4 #b7 a piece ( rubb]-b& tub+1 su* z is kn[n z bill-tie tub+1 & fit into ! m\? ( ! funnel a p]=at$ porcela9 crucible 7,goo* crucible71 mak+ sure t :5 ! crucible is g5tly =c$ into ! m\? ( ! funnel an airtight jo9t results4 7,a small #a or #a-a_/d-;in* glass funnel may be us$1 9 :i* case ! rubb] tub+ is /ret*$ ov] ! top ( ! funnel & !n drawn up ov] ! side ( ! crucible until an air-tight jo9t is secur$47 ,,illu/ration3 ,,fig4 #b ,fit ! funnel into ! /opp] ( a filt] bottle1 & connect ! filt] bottle ) ! suction pump4 ,susp5d "s f9ely divid$ asbe/os1 :i* has be5 wa%$ ) acid1 9 #bj to #cj cc4 ( wat] 7,note #a72 all[ ?is to settle1 p\r (f ! v f9e p>ticles1 & !n p\r "s ( ! mixture cauti\sly into ! crucible until an ev5 felt ( asbe/os1 n ov] #a_/cb in* 9 ?ickness1 is =m$4 ,a g5tle suction mu/ be appli$ :ile prep>+ ?is felt4 ,wa% ! felt ?or\ghly by pass+ ?r\gh x di/ill$ wat] until all f9e or loose p>ticles are remov$1 increas+ ! suction at ! la/ until no m wat] c be drawn out ( x2 place on top ( ! felt ! small1 p]=at$ porcela9 disc & hold x 9 place by p\r+ a v ?9 lay] ( asbe/os ov] x1 wa%+ ! :ole c>efully2 !n place ! crucible 9 a small beak]1 & place bo? 9 a dry+ closet at #ajj-aaj;,c4 = ?irty to =ty m9utes4 ,cool ! crucible 9 a desiccator1 & weigh4 ,heat aga9 = tw5ty to ?irty m9utes1 cool1 & aga9 weigh1 repeat+ ?is until ! weight is con/ant )9 #j4jjjc gram4 ,! filt] is !n ready = use4 ,place ! crucible 9 ! funnel1 & apply a g5tle suction1 6aft] :i*6 ! solution to be filt]$ may be p\r$ 9 )\t di/urb+ ! asbe/os felt4 ,:5 p\r+ liquid onto a ,goo* filt] hold ! /irr+-rod at fir/ well d[n 9 ! crucible1 s t ! liquid does n fall ) any =ce ^u ! asbe/os1 & aft]w>d keep ! crucible w fill$ ) ! solution4 ,p\r ! liquid above ! silv] *loride sl[ly onto ! filt]1 leav+ ! precipitate 9 ! beak] z f> z possible4 ,wa% ! precipitate twice by decantation ) w>m wat]2 !n transf] x to ! filt] ) ! aid ( a /irr+-rod ) a rubb] tip & a /ream f ! wa%-bottle4 ,exam9e ! fir/ portions ( ! filtrate :i* pass ?r\gh ! filt] ) great c>e = asbe/os fib]s1 :i* are mo/ likely to be lo/ at ?is po9t4 ,refilt] ! liquid if any fib]s are visible4 ,f9ally1 wa% ! precipitate ?or\ghly ) w>m wat] until free f soluble silv] salts4 ,to te/ ! wa%+s1 disconnect ! suction at ! flask & remove ! funnel or filt] tube f ! suction flask4 ,hold ! end ( ! tube ov] ! m\? ( a small te/ tube & add f a wa%-bottle #b-c cc4 ( wat]4 ,all[ ! wat] to drip ?r\gh into ! te/ tube & add a drop ( dilute hydro*loric acid4 ,no precipitate or cl\d %\ld =m 9 ! wa%-wat] 7,note #af74 ,dry ! filt] & cont5ts at #ajj-aaj;,c4 until ! weight is con/ant )9 #j4jjjc gram1 z describ$ = ! prep>ation ( ! filt]4 ,d$uct ! weight ( ! dry crucible f ! f9al weight1 & f ! weight ( silv] *loride ?us obta9$ calculate ! p]c5tage ( *lor9e 9 ! sample ( sodium *loride4 ,note #a3 ,! wa%$ asbe/os = ?is type ( filt] is prep>$ by dige/+ 9 conc5trat$ hydro*loric acid1 long-fib]$ asbe/os :i* has be5 cut 9 pieces ( ab\t #j4e cm4 9 l5g?4 ,aft] dige/ion1 ! asbe/os is filt]$ (f on a filt] plate & wa%$ ) hot1 di/ill$ wat] until free f *lorides4 ,a small portion ( ! asbe/os is %ak5 ) wat]1 =m+ a ?9 susp5sion1 :i* is bottl$ & kept = use4 ,note #b3 ,! nitric acid is add$ be=e precipitation to less5 ! t5d5cy ( ! silv] *loride to c>ry d[n ) x o!r sub/ances :i* might be precipitat$ f a neutral solution4 ,a l>ge excess ( ! acid w\ld ex]t a slight solv5t action ^u ! *loride4 ,note #c3 ,! solution %\ld n be boil$ aft] ! addition ( ! nitric acid be=e ! pres5ce ( an excess ( silv] nitrate is assur$1 s9ce a slight int]action betwe5 ! nitric acid & ! sodium *loride is possible1 by :i* a loss ( *lor9e1 ei!r z su* or z hydro*loric acid1 might ensue4 ,! pres5ce ( an excess ( ! precipitant c usually be recogniz$ at ! "t ( its addition1 by ! increas$ read9ess ) :i* ! precipitate coagulates & settles4 ,note #d3 ,! precipitate %\ld n be expos$ to /rong sunlight1 s9ce "u ^? conditions a r$uction ( ! silv] *loride ensues :i* is accompani$ by a loss ( *lor9e4 ,! sup]ficial alt]ation :i* ! *loride und]goes 9 diffus$ daylight is n suffici5t to mat]ially affect ! accuracy ( ! det]m9ation4 ,x %\ld be not$1 h[ev]1 t a slight error does result f ! effect ( light ^u ! silv] *loride precipitate & 9 cases 9 :i* ! greate/ obta9able accuracy is requir$1 ! proc$ure describ$ "u ,me?od ,b %\ld be foll[$1 9 :i* ?is slight r$uction ( ! silv] *loride is correct$ by subsequ5t treatm5t ) nitric & hydro*loric acids4 ,note #e3 ,! asbe/os us$ 9 ! ,goo* filt] %\ld be ( ! f9e/ quality & capable ( division into m9ute fibr\s p>ticles4 ,a co>se felt is n satisfactory4 ,note #f3 ,! precipitate mu/ be wa%$ ) w>m wat] until x is absolutely free f silv] & sodium nitrates4 ,x may be assum$ t ! sodium salt is completely remov$ :5 ! wa%-wat] %[s no evid5ce ( silv]4 ,x mu/ be borne 9 m9d t silv] *loride is some:at soluble 9 hydro*loric acid1 & only a s+le drop %\ld be add$4 ,! wa%+ %\ld be cont9u$ until no cl\d9ess :atev] c be detect$ 9 #c cc4 ( ! wa%+s4 ,silv] *loride is b slightly soluble 9 wat]4 ,! solubility v>ies ) its physical condition )9 small limits1 & is ab\t #j4jjah gram p] lit] at #ah;,c4 = ! curdy v>iety usually precipitat$4 ,! *loride is also some:at soluble 9 solutions ( _m *lorides1 9 solutions ( silv] nitrate1 & 9 conc5trat$ nitric acid4 ,z a matt] ( economy1 ! filtrate1 :i* conta9s :atev] silv] nitrate 0 add$ 9 excess1 may be set aside4 ,! silv] c be precipitat$ z *loride & lat] conv]t$ into silv] nitrate4 ,note #g3 ,! use ( ! ,goo* filt] comm5ds itself /rongly :5 a consid]able numb] ( halog5 det]m9ations are to be made1 s9ce successive portions ( ! silv] halides may be filt]$ on ! same filt]1 )\t ! removal ( ! prec$+ portions1 until ! crucible is ab\t two ?irds fill$4 ,if ! felt is prop]ly prep>$1 filtration & wa%+ are rapidly accompli%$ on ?is filt]1 & ?is1 comb9$ ) ! possibility ( collect+ sev]al precipitates on ! same filt]1 is a /rong argum5t 9 favor ( its use ) any b gelat9\s precipitates4 6,me?od ,b4 ,) ! ,use ( a ,pap] ,filt]6 ,,proc$ure4--,weigh out two portions ( sodium *loride ( ab\t #j4be-j4c gram ea* & proce$ ) ! precipitation ( ! silv] *loride z describ$ "u ,me?od ,a above4 ,:5 ! *loride is ready = filtration prep>e two #i cm4 wa%$ pap] filt]s 7see ,app5dix74 ,p\r ! liquid above ! precipitates ?r\gh ! filt]s1 wa% twice by decantation & transf] ! precipitates to ! filt]s1 f9ally wa%+ !m until free f silv] solution z describ$4 ,! funnel %\ld !n be cov]$ ) a moi/5$ filt] pap] by /ret*+ x ov] ! top & edges1 to :i* x w adh]e on dry+4 ,x %\ld be prop]ly label$ ) ! /ud5t's "n & desk numb]1 & !n plac$ 9 a dry+ closet1 at a temp]ature ( ab\t #ajj-aaj;,c41 until completely dry4 ,! p]fectly dry filt] is !n op5$ ov] a circul> piece ( clean1 smoo?1 glaz$ pap] ab\t six in*es 9 diamet]1 plac$ ^u a l>g] piece ab\t twelve in*es 9 diamet]4 ,! precipitate is remov$ f ! filt] z completely z possible by rubb+ ! sides g5tly toge!r1 or by scrap+ !m cauti\sly ) a fea!r :i* has be5 cut close to ! quill & is slightly /iff 7,note #a74 ,9 ei!r case1 c>e mu/ be tak5 n to rub (f any consid]able quantity ( ! pap]1 nor to lose silv] *loride 9 ! =m ( du/4 ,cov] ! precipitate on ! glaz$ pap] ) a wat*-glass to prev5t loss ( f9e p>ticles & to protect x f du/ f ! air4 ,fold ! filt] pap] c>efully1 roll x into a small cone1 & w9d loosely ar\nd 6! top6 a piece ( small plat9um wire 7,note #b74 ,hold ! filt] by ! wire ov] a small porcela9 crucible 7:i* has be5 clean$1 ignit$1 cool$ 9 a desiccator1 & weigh$71 ignite x1 & all[ ! a% to fall into ! crucible4 ,place ! crucible ^u a clean clay triangle1 on its side1 & ignite1 ) a l[ flame well at its base1 until all ! c>bon ( ! filt] has be5 consum$4 ,all[ ! crucible to cool1 add two drops ( conc5trat$ nitric acid & "o drop ( conc5trat$ hydro*loric acid1 & heat 6v cauti\sly61 to avoid spatt]+1 until ! acids h be5 expell$2 !n transf] ! ma9 portion ( ! precipitate f ! glaz$ pap] to ! cool$ crucible1 plac+ ! latt] on ! l>g] piece ( glaz$ pap] & bru%+ ! precipitate f ! small] piece into x1 sweep+ (f all p>ticles belong+ to ! det]m9ation4 ,moi/5 ! precipitate ) two drops ( conc5trat$ nitric acid & "o drop ( conc5trat$ hydro*loric acid1 & aga9 heat ) great caution until ! acids are expell$ & ! precipitate is :ite1 :5 ! temp]ature is sl[ly rais$ until ! silv] *loride j beg9s to fuse at ! edges 7,note #c74 ,! crucible is !n cool$ 9 a desiccator & weigh$1 aft] :i* ! heat+ 7)\t ! addition ( acids7 is repeat$1 & x is aga9 weigh$4 ,?is mu/ be cont9u$ until ! weight is con/ant )9 #j4jjjc gram 9 two consecutive weigh+s4 ,d$uct ! weight ( ! crucible1 & calculate ! p]c5tage ( *lor9e 9 ! sample ( sodium *loride tak5 = analysis4 ,note #a3 ,! sep>ation ( ! silv] *loride f ! filt] is ess5tial1 s9ce ! burn+ c>bon ( ! pap] w\ld r$uce a consid]able quantity ( ! precipitate to metallic silv]1 & its complete reconv]sion to ! *loride )9 ! crucible1 by means ( acids1 w\ld be accompani$ by "s difficulty4 ,! small am\nt ( silv] r$uc$ f ! *loride adh]+ to ! filt] pap] aft] sep>at+ ! bulk ( ! precipitate1 & ignit+ ! pap] z prescrib$1 c be dissolv$ 9 nitric acid1 & completely reconv]t$ to *loride by hydro*loric acid4 ,! subsequ5t addition ( ! two acids to ! ma9 portion ( ! precipitate re/ores ! *lor9e to any *loride :i* may h be5 p>tially r$uc$ by ! sunlight4 ,! excess ( ! acids is volatiliz$ by heat+4 ,note #b3 ,! plat9um wire is wrapp$ ar\nd ! top ( ! filt] dur+ its inc9]ation to avoid contact ) any r$uc$ silv] f ! r$uction ( ! precipitate4 ,if ! wire 7 plac$ ne>] ! apex1 su* contact c\ld h>dly be avoid$4 ,note #c3 ,silv] *loride %\ld n be heat$ to complete fusion1 s9ce a slight loss by volatilization is possible at high temp]atures4 ,! temp]ature ( fusion is n always suffici5t to de/roy filt] %r$s2 h5ce ^! %\ld n be all[$ to contam9ate ! precipitate4 ,,det]m9ation ,,( ,,iron ,,& ,,( ,,sulphur ,,9 ,,f]r\s ,,ammonium ,,sulphate1 ,,feso#d47,,nh#d7b,,s#d4f;,h#b,o ,,det]m9ation ,,( ,,iron ,,proc$ure4--,weigh out into beak]s 7#bjj-bej cc47 two portions ( ! sample 7,note #a7 ( ab\t #a gram ea* & dissolve ^! 9 #ej cc4 ( wat]1 to :i* #a cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab7 has be5 add$ 7,note #b74 ,heat ! solution to boil+1 & :ile at ! boil+ po9t add conc5trat$ nitric acid 7sp4 gr4 #a4db71 6drop by drop6 7not+ ! volume us$71 until ! br[n coloration1 :i* appe>s aft] ! addition ( a "p ( ! nitric acid1 gives place to a yell[ or r$ 7,note #c74 ,avoid a l>ge excess ( nitric acid1 b be sure t ! action is complete4 ,p\r ?is solution cauti\sly into ab\t #bjj cc4 ( wat]1 conta9+ a slight excess ( ammonia4 ,calculate = ?is purpose ! am\nt ( aque\s ammonia requir$ to neutralize ! hydro*loric & nitric acids add$ 7see ,app5dix = data71 & also to precipitate ! iron z f]ric hydroxide f ! weight ( ! f]r\s ammonium sulphate tak5 = analysis1 assum+ x to be pure 7,note #d74 ,! volume ?us calculat$ w be 9 excess ( t actually requir$ = precipitation1 s9ce ! acids are 9 "p consum$ 9 ! oxidation process1 or are volatiliz$4 ,heat ! solution to boil+1 & all[ ! precipitat$ f]ric hydroxide to settle4 ,decant ! cle> liquid ?r\gh a wa%$ filt] 7#i cm471 keep+ z mu* ( ! precipitate 9 ! beak] z possible4 ,wa% twice by decantation ) #ajj cc4 ( hot wat]4 ,res]ve ! filtrate4 ,dissolve ! iron f ! filt] ) hot1 dilute hydro*loric acid 7sp4 gr4 #a4ab71 add+ x 9 small portions1 us+ z little z possible & not+ ! volume us$4 ,collect ! solution 9 ! beak] 9 :i* precipitation took place4 ,add #a cc4 ( nitric acid 7sp4 gr4 #a4db71 boil = a few mom5ts1 & aga9 p\r into a calculat$ excess ( ammonia4 ,wa% ! precipitate twice by decantation1 & f9ally transf] x to ! orig9al filt]4 ,wa% cont9u\sly ) hot wat] until f9ally #c cc4 ( ! wa%+s1 acidifi$ ) nitric acid 7,note #e71 %[ no evid5ces ( ! pres5ce ( *lorides :5 te/$ ) silv] nitrate4 ,! filtrate & wa%+s are comb9$ ) ^? f ! fir/ precipitation & treat$ = ! det]m9ation ( sulphur1 z prescrib$ on page #aab4 ,note #a3 ,if a selection ( pure mat]ial = analysis is to be made1 cry/als :i* are cl\dy are to be avoid$ on acc\nt ( loss ( wat] ( cry/allization2 & also ^? :i* are r$1 indicat+ ! pres5ce ( f]ric iron4 ,if1 on ! o!r h&1 ! value ( an av]age sample ( mat]ial is desir$1 x is pref]able to gr9d ! :ole toge!r1 mix ?or\ghly1 & take a sample f ! mixture = analysis4 ,note #b3 ,:5 aque\s solutions ( f]r\s comp\nds are heat$ 9 ! air1 oxidation ( ! ,fe ions to ,fe ions readily occurs 9 ! abs5ce ( free acid4 ,! ,h & ,,oh- ions f wat] are involv$ 9 ! oxidation process & ! result is1 9 effect1 ! =mation ( "s f]ric hydroxide :i* t5ds to sep>ate4 ,moreov]1 at ! boil+ temp]ature1 ! f]ric sulphate produc$ by ! oxidation hydrolyzes 9 "p ) ! =mation ( a basic f]ric sulphate1 :i* also t5ds to sep>ate f solution4 ,! addition ( ! hydro*loric acid prev5ts ! =mation ( f]ric hydroxide1 & s f> r$uces ! ionization ( ! wat] t ! hydrolysis ( ! f]ric sulphate is also prev5t$1 & no precipitation occurs on heat+4 ,note #c3 ,! nitric acid1 aft] atta9+ a mod]ate /r5g?1 oxidizes ! ,fe ions to ,fe ions ) ! =mation ( an int]m$iate nitroso-comp\nd simil> 9 "* to t =m$ 9 ! r+-te/ = nitrates4 ,! nitric oxide is driv5 out by heat1 & ! solution !n %[s by its color ! pres5ce ( f]ric comp\nds4 ,a drop ( ! oxidiz$ solution %\ld be te/$ on a wat*-glass ) potassium f]ricyanide1 to insure a complete oxidation4 ,?is oxidation ( ! iron is necess>y1 s9ce ,fe ions are n completely precipitat$ by ammonia4 ,! ionic *anges :i* are involv$ 9 ?is oxidation are p]haps mo/ simply express$ by ! equation #c;,fe ,,no#c- #d;,h -- #c;,fe #b;,h#b,o ,,no1 ! ,h ions com+ f ! acid 9 ! solution1 9 ?is case ei!r ! nitric or ! hydro*loric acid4 ,! full equation on :i* ?is is bas$ may be writt5 ?us3 #f;,fe,s,o#d #b;,,hno#c #f;,h,cl -- #b;,fe#b7,,s#d7c #b;,fe,cl#c #b,,no #d;,h#b,o1 assum+ t only en\gh nitric acid is add$ to complete ! oxidation4 ,note #d3 ,! f]ric hydroxide precipitate t5ds to c>ry d[n "s sulphuric acid 9 ! =m ( basic f]ric sulphate4 ,?is t5d5cy is less5$ if ! solution ( ! iron is add$ to an excess ( ,,oh- ions f ! ammonium hydroxide1 s9ce "u ^! conditions imm$iate & complete precipitation ( ! f]ric hydroxide ensues4 ,a gradual neutralization ) ammonia w\ld result 9 ! local =mation ( a neutral solution )9 ! liquid1 & subsequ5t deposition ( a basic sulphate z a consequ5ce ( a local defici5cy ( ,,oh- ions f ! ,,nh#d,,oh & a p>tial hydrolysis ( ! f]ric salt4 ,ev5 ) ?is precaution ! entire abs5ce ( sulphates f ! fir/ iron precipitate is n assur$4 ,x is1 !re=e1 r$issolv$ & aga9 ?r[n d[n by ammonia4 ,! organic matt] ( ! filt] pap] may occasion a p>tial r$uction ( ! iron dur+ solution1 ) consequ5t possibility ( incomplete subsequ5t precipitation ) ammonia4 ,! nitric acid is add$ to reoxidize ?is iron4 ,to avoid errors aris+ f ! solv5t action ( ammoniacal liquids ^u glass1 ! iron precipitate %\ld be filt]$ )\t unnecess>y delay4 ,note #e3 ,! wa%+s f ! f]ric hydroxide are acidifi$ ) nitric acid1 be=e te/+ ) silv] nitrate1 to de/roy ! ammonia :i* is a solv5t ( silv] *loride4 ,! use ( suction to promote filtration & wa%+ is p]missible1 ?\gh n prescrib$4 ,! precipitate %\ld n be all[$ to dry dur+ ! wa%+4 6,ignition ( ! ,iron ,precipitate6 ,heat a plat9um or porcela9 crucible1 cool x 9 a desiccator & weigh1 repeat+ until a con/ant weight is obta9$4 ,fold ! top ( ! filt] pap] ov] ! moi/ precipitate ( f]ric hydroxide & transf] x cauti\sly to ! crucible4 ,wipe ! inside ( ! funnel ) a small fragm5t ( wa%$ filt] pap]1 if necess>y1 & place ! pap] 9 ! crucible4 ,incl9e ! crucible on its side1 on a triangle support$ on a r+-/&1 & /& ! cov] on edge at ! m\? ( ! crucible4 ,place a burn] bel[ ! front edge ( ! crucible1 us+ a l[ flame & protect+ x f drafts ( air by means ( a *imney4 ,! heat f ! burn] is ?us reflect$ into ! crucible & dries ! precipitate )\t dang] ( loss z ! result ( a sudd5 g5]ation ( /eam )9 ! mass ( f]ric hydroxide4 ,z ! dry+ progresses ! burn] may be gradually mov$ t[>d ! base ( ! crucible & ! flame increas$ until ! pap] ( ! filt] beg9s to *> & f9ally to smoke1 z ! volatile matt] is expell$4 ,?is is kn[n z smok+ (f a filt]1 & ! temp]ature %\ld n be rais$ suffici5tly high dur+ ?is process to cause ! pap] to ignite1 z ! air curr5ts produc$ by ! flame ( ! blaz+ pap] may c>ry away p>ticles ( ! precipitate4 ,:5 ! pap] is fully *>r$1 move ! burn] to ! base ( ! crucible & raise ! temp]ature to ! full heat ( ! burn] = fifte5 m9utes1 ) ! crucible /ill incl9$ on its side1 b )\t ! cov] 7,note #a74 ,f9ally set ! crucible upright 9 ! triangle1 cov] x1 & heat at ! full temp]ature ( a bla/ lamp or o!r high temp]ature burn]4 ,cool & weigh 9 ! usual mann] 7,note #b74 ,repeat ! /rong heat+ until ! weight is con/ant )9 #j4jjjc gram4 ,f ! weight ( f]ric oxide 7,fe#b,o#c7 calculate ! p]c5tage ( iron 7,fe7 9 ! sample 7,note #c74 ,note #a3 ,^! directions = ! ignition ( ! precipitate mu/ be closely foll[$4 ,a ready access ( atmosph]ic oxyg5 is ( special importance to insure ! reoxidation to f]ric oxide ( any iron :i* may be r$uc$ to magnetic oxide 7,fe#c,o#d7 dur+ ! combu/ion ( ! filt]4 ,! f9al heat+ ov] ! bla/ lamp is ess5tial = ! complete expulsion ( ! la/ traces ( wat] f ! hydroxide4 ,note #b3 ,ignit$ f]ric oxide is some:at hygroscopic4 ,on ?is acc\nt ! weigh+s mu/ be promptly complet$ aft] removal f ! desiccator4 ,9 all weigh+s aft] ! fir/ x is well to place ! weights ^u ! balance-pan be=e remov+ ! crucible f ! desiccator4 ,x is !n only necess>y to move ! rid] to obta9 ! weight4 ,note #c3 ,! gravimetric det]m9ation ( alum9ium or *romium is comp>able ) t ( iron j describ$1 ) ! additional precaution t ! solution mu/ be boil$ until x conta9s b a v slight excess ( ammonia1 s9ce ! hydroxides ( alum9ium & *romium are m soluble ?an f]ric hydroxide4 ,! mo/ important prop]ties ( ^! hydroxides1 f a quantitative /&po9t1 o!r ?an ^? m5tion$1 are ! foll[+3 ,all are precipitable by ! hydroxides ( sodium & potassium1 b always inclose "s ( ! precipitant1 & %\ld be reprecipitat$ ) ammonium hydroxide be=e ignition to oxides4 ,*romium & alum9ium hydroxides dissolve 9 an excess ( ! cau/ic alkalies & =m anions1 probably ( ! =mula ,al,o#b- & ,cr,o#b-4 ,*romium hydroxide is reprecipitat$ f ?is solution on boil+4 ,:5 fir/ precipitat$ ! hydroxides are all readily soluble 9 acids1 b alum9ium hydroxide dissolves ) consid]able difficulty aft] /&+ or boil+ = "s "t4 ,! precipitation ( ! hydroxides is promot$ by ! pres5ce ( ammonium *loride1 b is p>tially or entirely prev5t$ by ! pres5ce ( t>t>ic or citric acids1 glyc]9e1 sug>s1 & "s o!r =ms ( soluble organic matt]4 ,! hydroxides yield on ignition an oxide suitable = weigh+ 7,al#b,o#c1 ,cr#b,o#c1 ,fe#b,o#c74 ,,det]m9ation ,,( ,,sulphur ,,proc$ure4--,add to ! comb9$ filtrates f ! f]ric hydroxide ab\t #j4f gram ( anhydr\s sodium c>bonate2 cov] ! beak]1 & !n add dilute hydro*loric acid 7sp4 gr4 #a4ab7 9 mod]ate excess & evaporate to dryness on ! wat] ba?4 ,add #aj cc4 ( conc5trat$ hydro*loric acid 7sp4 gr4 #a4bj7 to ! residue1 & aga9 evaporate to dryness on ! ba?4 ,dissolve ! residue 9 wat]1 filt] if n cle>1 transf] to a #gjj cc4 beak]1 dilute to ab\t #djj cc41 & cauti\sly add hydro*loric acid until ! solution %[s a di/9ctly acid reaction 7,note #a74 ,heat ! solution to boil+1 & add 6v sl[ly6 & ) con/ant /irr+1 #bj cc4 9 excess ( ! calculat$ am\nt ( a hot b>ium *loride solution1 conta9+ ab\t #bj grams ,ba,cl#b4b;,h#b,o p] lit] 7,notes #b & #c74 ,cont9ue ! boil+ = ab\t two m9utes1 all[ ! precipitate to settle1 & decant ! liquid at ! end ( half an h\r 7,note #d74 ,replace ! beak] conta9+ ! orig9al filtrate by a clean beak]1 wa% ! precipitat$ sulphate by decantation ) hot wat]1 & subsequ5tly ^u ! filt] until x is fre$ f *lorides1 te/+ ! wa%+s z describ$ 9 ! det]m9ation ( iron4 ,! filt] is !n transf]r$ to a plat9um or porcela9 crucible & ignit$1 z describ$ above1 until ! weight is con/ant 7,note #e74 ,f ! weight ( b>ium sulphate 7,ba,s,o#d7 obta9$1 calculate ! p]c5tage ( sulphur 7,s7 9 ! sample4 ,note #a3 ,b>ium sulphate is slightly soluble 9 hydro*loric acid1 ev5 dilute1 probably z a result ( ! r$uction 9 ! degree ( dissociation ( sulphuric acid 9 ! pres5ce ( ! ,h ions ( ! hydro*loric acid1 & possibly because ( ! =mation ( a complex anion made up ( b>ium & *lor9e2 h5ce only ! smalle/ excess %\ld be add$ ov] ! am\nt requir$ to acidify ! solution4 ,note #b3 ,! ionic *anges involv$ 9 ! precipitation ( b>ium sulphate are v simple3 ,ba ,,s#d-- -- ,ba,s,o#d ,?is case af=ds "o ( ! be/ illu/rations ( ! effect ( an excess ( a precipitant 9 decreas+ ! solubility ( a precipitate4 ,if ! conditions are consid]$ :i* exi/ at ! mom5t :5 j en\gh ( ! ,ba ions h be5 add$ to correspond to ! ,,s#d-- ions 9 ! solution1 x w be se5 t ne>ly all ( ! b>ium sulphate has be5 precipitat$1 & t ! small am\nt :i* !n rema9s 9 ! solution :i* is 9 contact ) ! precipitate mu/ repres5t a saturat$ solution = ! exi/+ temp]ature1 & t ?is solution is comp>able ) a solution ( sug> to :i* m sug> has be5 add$ ?an w dissolve4 ,x %\ld be borne 9 m9d t ! quantity ( b>ium sulphate 9 ?is 6saturat$ solution is a con/ant quantity6 = ! exi/+ conditions4 ,! dissolv$ b>ium sulphate1 l any electrolyte1 is dissociat$1 & ! equilibrium conditions may be express$ ?us3 76,conc'n ,ba x ,conc'n ,,s#d--7_/7;,conc'n ,ba,s,o#d7 ,con/461 & s9ce 6,conc'n ,ba,s,o#d6 = ! saturat$ solution has a con/ant value 7:i* is v small71 x may be elim9at$1 :5 ! expression becomes 6,conc'n ,ba x ,conc'n ,,s#d-- ,con/461 :i* is ! solubility product ( ,ba,s,o#d4 ,if1 n[1 an excess ( ! precipitant1 a soluble b>ium salt1 is add$ 9 ! =m ( a relatively conc5trat$ solution 7! slight *ange ( volume ( a few cubic c5timet]s may be disreg>d$ = ! pres5t discussion7 ! conc5tration ( ! ,ba ions is mu* increas$1 & z a consequ5ce ! 6,conc'n ,,s#d6 mu/ decrease 9 proportion if ! value ( ! expression is to rema9 con/ant1 :i* is a requisite condition if ! law ( mass action ^u :i* our argum5t dep5ds holds true4 ,9 o!r words1 ,,s#d-- ions mu/ comb9e ) "s ( ! add$ ,ba ions to =m ,ba,s,o#d2 b x w be recall$ t ! solution is already saturat$ ) ,ba,s,o#d1 & ?is fre%ly =m$ quantity mu/1 !re=e1 sep>ate & add itself to ! precipitate4 ,?is is exactly :at is desir$ 9 ord] to insure m complete precipitation & great] accuracy1 & leads to ! conclusion t ! l>g] ! excess ( ! precipitant add$ ! m successful ! analysis2 b a practical limit is plac$ ^u ! quantity ( ! precipitant :i* may be prop]ly add$ by o!r conditions1 z /at$ 9 ! foll[+ note4 ,note #c3 ,b>ium sulphate1 9 a l>g] measure ?an mo/ comp\nds1 t5ds to c>ry d[n o!r sub/ances :i* are pres5t 9 ! solution f :i* x sep>ates1 ev5 :5 ^! o!r sub/ances are relatively soluble1 & includ+ ! b>ium *loride us$ z ! precipitant4 ,?is is also notably true 9 ! case ( nitrates & *lorates ( ! alkalies1 & ( f]ric comp\nds2 &1 s9ce 9 ?is analysis ammonium nitrate has result$ f ! neutralization ( ! excess ( ! nitric acid add$ to oxidize ! iron1 x is ess5tial t ?is %\ld be de/roy$ by repeat$ evaporation ) a relatively l>ge quantity ( hydro*loric acid4 ,dur+ evaporation a mutual decomposition ( ! two acids takes place1 & ! nitric acid is f9ally decompos$ & expell$ by ! excess ( hydro*loric acid4 ,iron is usually f\nd 9 ! precipitate ( b>ium sulphate :5 ?r[n d[n f hot solutions 9 ! pres5ce ( f]ric salts4 ,?is1 accord+ to ,ku/] & ,?iel 76,zeit4 anorg4 ,*em461 #bb1 #dbd71 is due to ! =mation ( a complex ion 7,fe7,,s#d7b7 :i* precipitates ) ! ,ba ion1 :ile ,ri*>ds 76,zeit4 anorg4 ,*em461 #bc1 #chc7 ascribes x to hydrolytic action1 :i* causes ! =mation ( a basic f]ric complex :i* is occlud$ 9 ! b>ium precipitate4 ,:atev] ! "* ( ! comp\nd may be1 x has be5 %[n t x loses sulphuric anhydride ^u ignition1 caus+ l[ results1 ev5 ?\gh ! precipitate conta9s iron4 ,! contam9ation ( ! b>ium sulphate by iron is mu* less 9 ! pres5ce ( f]r\s ?an f]ric salts4 ,if1 !re=e1 ! sulphur alone 7 to be det]m9$ 9 ! f]r\s ammonium sulphate1 ! precipitation by b>ium might be made directly f an aque\s solution ( ! salt1 :i* _h be5 made slightly acid ) hydro*loric acid4 ,note #d3 ,! precipitation ( ! b>ium sulphate is probably complete at ! end ( a half-h\r1 & ! solution may safely be filt]$ at ! expiration ( t "t if x is desir$ to ha/5 ! analysis4 ,z already not$1 _m precipitates ( ! g5]al "* ( ?is sulphate t5d to gr[ m co>sely granul> if dige/$ = "s "t ) ! liquid f :i* !y h sep>at$4 ,x is !re=e well to all[ ! precipitate to /& 9 a w>m place = sev]al h\rs1 if practicable1 to promote ease ( filtration4 ,! filtrate & wa%+s %\ld always be c>efully exam9$ = m9ute quantities ( ! sulphate :i* may pass ?r\gh ! pores ( ! filt]4 ,?is is be/ accompli%$ by imp>t+ to ! filtrate a g5tle rot>y motion1 :5 ! sulphate1 if pres5t1 w collect at ! c5t] ( ! bottom ( ! beak]4 ,note #e3 ,a r$uction ( b>ium sulphate to ! sulphide may v readily be caus$ by ! r$uc+ action ( ! burn+ c>bon ( ! filt]1 & mu* c>e %\ld be tak5 to prev5t any consid]able r$uction f ?is cause4 ,subsequ5t ignition1 ) ready access ( air1 reconv]ts ! sulphide to sulphate unless a consid]able r$uction has occurr$4 ,9 ! latt] case x is exp$i5t to add "o or two drops ( sulphuric acid & to heat cauti\sly until ! excess ( acid is expell$4 ,note #f3 ,b>ium sulphate requires ab\t #djj1jjj p>ts ( wat] = its solution4 ,x is n decompos$ at a r$ heat b suff]s loss1 probably ( sulphur trioxide1 at a temp]ature above #ijj;,c4 ,,det]m9ation ,,( ,,sulphur ,,9 ,,b>ium ,,sulphate ,,proc$ure4--,weigh out1 into plat9um crucibles1 two portions ( ab\t #j4e gram ( ! sulphate4 ,mix ea* 9 ! crucible ) five to six times its weight ( anhydr\s sodium c>bonate4 ,?is c be/ be done by plac+ ! crucible on a piece ( glaz$ pap] & /irr+ ! mixture ) a clean1 dry /irr+-rod1 :i* may f9ally be wip$ (f ) a small fragm5t ( filt] pap]1 ! latt] be+ plac$ 9 ! crucible4 ,cov] ! crucible & heat until a quiet1 liquid fusion ensues4 ,remove ! burn]1 & tip ! crucible until ! fus$ mass fl[s ne>ly to its m\?4 ,hold x 9 t position until ! mass has solidifi$4 ,:5 cold1 ! mat]ial may usually be deta*$ 9 a lump by tapp+ ! crucible or g5tly press+ x ne> its upp] edge4 ,if x /ill adh]es1 a cubic c5timet] or s ( wat] may be plac$ 9 ! cold crucible & cauti\sly br\ght to boil+1 :5 ! cake w become loos5$ & may be remov$ & plac$ 9 ab\t #bej cc4 ( hot1 di/ill$ wat] to dissolve4 ,clean ! crucible completely1 rubb+ ! sides ) a rubb]-cov]$ /irr+-rod1 if ne$ be4 ,:5 ! fus$ mass has completely dis9tegrat$ & no?+ fur!r w dissolve1 decant ! solution f ! residue ( b>ium c>bonate 7,note #a74 ,p\r ov] ! residue #bj cc4 ( a solution ( sodium c>bonate & #aj cc4 ( wat] & heat to g5tle boil+ = ab\t ?ree m9utes 7,note #b74 ,filt] (f ! c>bonate & wa% x ) hot wat]1 te/+ ! slightly acidifi$ wa%+s = sulphate & pres]v+ any precipitates :i* appe> 9 ^! te/s4 ,acidify ! filtrate ) hydro*loric acid until j acid1 br+ to boil+1 & sl[ly add hot b>ium *loride solution1 z 9 ! prec$+ det]m9ation4 ,add also any te/s f ! wa%+s 9 :i* precipitates h appe>$4 ,filt]1 wa%1 ignite1 & weigh4 ,f ! weight ( b>ium sulphate1 calculate ! p]c5tage ( sulphur 7,s7 9 ! sample4 ,note #a3 ,?is alkal9e fusion is mu* employ$ to dis9tegrate sub/ances ord9>ily insoluble 9 acids into two compon5ts1 "o ( :i* is wat] soluble & ! o!r acid soluble4 ,! reaction involv$ is3 ,ba,s,o#d ,na#b;,,co#c1 -- ,ba,c,o#c1 ,na#b,,s#d4 ,z ! sodium sulphate is soluble 9 wat]1 & ! b>ium c>bonate insoluble1 a sep>ation betwe5 !m is possible & ! sulphur c be det]m9$ 9 ! wat]-soluble portion4 ,x %\ld be not$ t ?is me?od c be appli$ to ! purification ( a precipitate ( b>ium sulphate if contam9at$ by mo/ ( ! sub/ances m5tion$ 9 ,note #c on page #aad4 ,! impurities pass into ! wat] solution toge!r ) ! sodium sulphate1 b1 be+ pres5t 9 su* m9ute am\nts1 d n aga9 precipitate ) ! b>ium sulphate4 ,note #b3 ,! b>ium c>bonate is boil$ ) sodium c>bonate solution be=e filtration because ! reaction above is rev]sible2 & x is only by keep+ ! sodium c>bonate pres5t 9 excess until ne>ly all ( ! sodium sulphate solution has be5 remov$ by filtration t ! rev]sion ( "s ( ! b>ium c>bonate to b>ium sulphate is prev5t$4 ,?is is an application ( ! pr9ciple ( mass action1 9 :i* ! conc5tration ( ! reag5t 7! c>bonate ion7 is kept z high z practicable & t ( ! sulphate ion z l[ z possible1 9 ord] to =ce ! reaction 9 ! desir$ direction 7see ,app5dix74 ,,det]m9ation ,,( ,,phosphoric ,,anhydride ,,9 ,,apatite ,! m9]al apatite is compos$ ( calcium phosphate1 associat$ ) calcium *loride1 or fluoride4 ,specim5s are easily obta9able :i* are ne>ly pure & leave on treatm5t ) acid only a slight silice\s residue4 ,= ! purpose ( gravimetric det]m9ation1 phosphoric acid is usually precipitat$ f ammoniacal solutions 9 ! =m ( magnesium ammonium phosphate :i*1 on ignition1 is conv]t$ into magnesium pyrophosphate4 ,s9ce ! calcium phosphate ( ! apatite is also insoluble 9 ammoniacal solutions1 ?is proc$ure _c be appli$ directly4 ,! sep>ation ( ! phosphoric acid f ! calcium mu/ fir/ be accompli%$ by precipitation 9 ! =m ( ammonium phosphomolybdate 9 nitric acid solution1 us+ ammonium molybdate z ! precipitant4 ,! yell[ precipitate1 z x is (t5 call$1 is n always ( a def9ite composition1 & !re=e n suitable = direct weigh+1 b may be dissolv$ 9 ammonia1 & ! phosphoric acid ?r[n out z magnesium ammonium phosphate f ! solution4 ,( ! sub/ances likely to occur 9 apatite1 silicic acid alone int]f]es ) ! precipitation ( ! phosphoric acid 9 nitric acid solution4 ,,precipitation ,,( ,,ammonium ,,phosphomolybdate ,,proc$ure4--,gr9d ! m9]al 9 an agate mort> until no grit is p]ceptible4 ,transf] ! sub/ance to a weigh+-tube1 & weigh out two portions1 n exce$+ #j4bj gram ea* 7,note #a7 into two beak]s ( ab\t #bjj cc4 capacity4 ,p\r ov] !m #bj cc4 ( dilute nitric acid 7sp4 gr4 #a4b7 & w>m g5tly until solv5t action has app>5tly ceas$4 ,evaporate ! solution cauti\sly to dryness1 heat ! residue = ab\t an h\r at #ajj-aaj;,c41 & treat x aga9 ) nitric acid z describ$ above2 sep>ate ! residue ( silica by filtration on a small filt] 7#g cm47 & wa% ) w>m wat]1 us+ z little z possible 7,note #b74 ,receive ! filtrate 9 a beak] 7#bjj-ejj cc474 ,te/ ! wa%+s ) ammonia = calcium phosphate1 b add all su* te/s 9 :i* a precipitate appe>s to ! orig9al nitrate 7,note #c74 ,! filtrate & wa%+s mu/ be kept z small z possible & %\ld n exce$ #ajj cc4 9 volume4 ,add aque\s ammonia 7sp4 gr4 #j4if7 until ! precipitate ( calcium phosphate fir/ produc$ j fails to r$issolve1 & !n add a few drops ( nitric acid until ?is is aga9 br\ght into solution 7,note #d74 ,w>m ! solution until x _c be com=tably held 9 ! h& 7ab\t #fj;,c47 &1 aft] removal ( ! burn]1 add #ge cc4 ( ammonium molybdate solution :i* has be5 6g5tly6 w>m$1 b :i* mu/ be p]fectly cle>4 ,all[ ! mixture to /& at a temp]ature ( ab\t #ej or #fj;,c4 = twelve h\rs 7,notes #e & #f74 ,filt] (f ! yell[ precipitate on a #i cm4 filt]1 & wa% by decantation ) a solution ( ammonium nitrate made acid ) nitric acid4#a ,all[ ! precipitate to rema9 9 ! beak] z f> z possible4 ,te/ ! wa%+s = calcium ) ammonia & ammonium oxalate 7,note #c74 ,footnote #a3 ,?is solution is prep>$ z foll[s3 ,mix #ajj cc4 ( ammonia solution 7sp4 gr4 #j4if7 ) #cbe cc4 ( nitric acid 7sp4 gr4 #a4b7 & dilute ) #ajj cc4 ( wat]4 ,add #aj cc4 ( molybdate solution to ! nitrate1 & leave x = a few h\rs4 ,x %\ld !n be c>efully exam9$ = a 6yell[6 precipitate2 a :ite precipitate may be neglect$4 ,note #a3 ,magnesium ammonium phosphate1 z not$ bel[1 is slightly soluble "u ! conditions ( op]ation4 ,consequ5tly ! unavoidable errors ( analysis are great] 9 ?is det]m9ation ?an 9 ^? :i* h prec$$ x1 & "s div]g5ce may be expect$ 9 duplicate analyses4 ,x is obvi\s t ! l>g] ! am\nt ( sub/ance tak5 = analysis ! less w be ! relative loss or ga9 due to unavoidable exp]im5tal errors2 b1 9 ?is in/ance1 a *eck is plac$ ^u ! am\nt ( mat]ial :i* may be tak5 bo? by ! bulk ( ! result+ precipitate ( ammonium phosphomolybdate & by ! excessive am\nt ( ammonium molybdate requir$ to effect complete sep>ation ( ! phosphoric acid1 s9ce a lib]al excess above ! !oretical quantity is dem&$4 ,molybdic acid is "o ( ! m exp5sive reag5ts4 ,note #b3 ,soluble silicic acid w\ld1 if pres5t1 p>tially sep>ate ) ! phosphomolybdate1 al?\gh n 9 comb9ation ) molybd5um4 ,its previ\s removal by dehydration is !re=e necess>y4 ,note #c3 ,:5 wa%+ ! silice\s residue ! filtrate may be te/$ = calcium by add+ ammonia1 s9ce t reag5t neutralizes ! acid :i* holds ! calcium phosphate 9 solution & causes precipitation2 b aft] ! removal ( ! phosphoric acid 9 comb9ation ) ! molybd5um1 ! addition ( an oxalate is requir$ to %[ ! pres5ce ( calcium4 ,note #d3 ,an excess ( nitric acid ex]ts a slight solv5t action1 :ile ammonium nitrate less5s ! solubility2 h5ce ! neutralization ( ! =m] by ammonia4 ,note #e3 ,! precipitation ( ! phosphomolybdate takes place m promptly 9 w>m ?an 9 cold solutions1 b ! temp]ature %\ld n exce$ #fj;,c4 dur+ precipitation2 a high] temp]ature t5ds to sep>ate molybdic acid f ! solution4 ,?is acid is ne>ly :ite1 & its deposition 9 ! filtrate on long /&+ %\ld n be mi/ak5 = a second precipitation ( ! yell[ precipitate4 ,! addition ( #ge cc4 ( ammonium molybdate solution insures ! pres5ce ( a lib]al excess ( ! reag5t1 b ! filtrate %\ld be te/$ z 9 all quantitative proc$ures4 ,! precipitation is probably complete 9 _m cases 9 less ?an twelve h\rs2 b x is bett]1 :5 practicable1 to all[ ! solution to /& = ?is l5g? ( "t4 ,vigor\s %ak+ or /irr+ promotes ! sep>ation ( ! precipitate4 ,note #f3 ,! composition ( ! yell[ precipitate und\bt$ly v>ies slightly ) v>y+ conditions at ! "t ( its =mation4 ,its composition may probably fairly be repres5t$ by ! =mula1 7,,nh#d7c,,po#d4ab,mo,o#c4;,h#b,o1 :5 precipitat$ "u ! conditions prescrib$ 9 ! proc$ure4 ,:atev] o!r v>iations may occur 9 its composition1 ! ratio ( #ab ,mo,o#c3a ,p seems to hold1 & ?is fact is utiliz$ 9 volumetric processes = ! det]m9ation ( phosphorus1 9 :i* ! molybd5um is r$uc$ to a l[] oxide & reoxidiz$ by a /&>d solution ( potassium p]manganate4 ,9 pr9ciple1 ! proc$ure is comp>able ) t describ$ = ! det]m9ation ( iron by p]manganate4 ,,precipitation ,,( ,,magnesium ,,ammonium ,,phosphate ,,proc$ure4--,dissolve ! precipitate ( phosphomolybdate ^u ! filt] by p\r+ ?r\gh x dilute aque\s ammonia 7"o volume ( dilute ammonia 7sp4 gr4 #j4if7 & ?ree volumes ( wat]1 :i* %\ld be c>efully measur$71 & receive ! solution 9 ! beak] conta9+ ! bulk ( ! precipitate4 ,! total volume ( nitrate & wa%+s %\ld n mu* exce$ #ajj cc4 ,acidify ! solution ) dilute hydro*loric acid1 & heat x ne>ly to boil+4 ,calculate ! volume ( magnesium ammonium *loride solution 7magnesia mixture7 requir$ to precipitate ! phosphoric acid1 assum+ #dj p] c5t ,p#b,o#e 9 ! apatite4 ,measure out ab\t #e cc4 9 excess ( ?is am\nt1 & p\r x into ! acid solution4 ,!n add sl[ly dilute ammonium hydroxide 7#a volume ( /rong ammonia 7sp4 gr4 #j4ij7 & #i volumes ( wat]71 /irr+ con/antly until a precipitate =ms4 ,!n add a volume ( filt]$1 conc5trat$ ammonia 7sp4 gr4 #j4ij7 equal to "o ?ird ( ! volume ( liquid 9 ! beak] 7,note #a74 ,all[ ! :ole to cool4 ,! precipitat$ magnesium ammonium phosphate %\ld !n be def9itely cry/all9e 9 appe>ance 7,note #b74 7,if x is desir$ to ha/5 ! precipitation1 ! solution may be cool$1 fir/ 9 cold & !n 9 ice-wat]1 & /irr$ 6con/antly6 = half an h\r1 :5 precipitation w usually be complete47 ,decant ! cle> liquid ?r\gh a filt]1 & transf] ! precipitate to ! filt]1 us+ z wa%-wat] a mixture ( "o volume ( conc5trat$ ammonia & ?ree volumes ( wat]4 ,x is n necess>y to clean ! beak] completely or to wa% ! precipitate ?or\ghly at ?is po9t1 z x is necess>y to purify x by reprecipitation4 ,note #a3 ,magnesium ammonium phosphate is n a :olly insoluble sub/ance1 ev5 "u ! mo/ favorable analytical conditions4 ,x is lea/ soluble 9 a liquid conta9+ "o f\r? ( its volume ( conc5trat$ aque\s ammonia 7sp4 gr4 #j4ij7 & ?is proportion %\ld be c>efully ma9ta9$ z prescrib$ 9 ! proc$ure4 ,on acc\nt ( ?is slight solubility ! volume ( solutions %\ld be kept z small z possible & ! am\nt ( wa%-wat] limit$ to t absolutely requir$4 ,a l>ge excess ( ! magnesium solution t5ds bo? to ?r[ out magnesium hydroxide 7%[n by a p]si/5tly floccul5t precipitate7 & to cause ! phosphate to c>ry d[n molybdic acid4 ,! t5d5cy ( ! magnesium precipitate to c>ry d[n molybdic acid is also increas$ if ! solution is too conc5trat$4 ,! volume %\ld n be less ?an #ij cc41 nor m ?an #abe cc41 at ! "t ( ! fir/ precipitation ) ! magnesia mixture4 ,note #b3 ,! magnesium ammonium phosphate %\ld be p]fectly cry/all9e1 & w be s if ! directions are foll[$4 ,! sl[ addition ( ! reag5t is ess5tial1 & ! /irr+ n less s4 ,/irr+ promotes ! sep>ation ( ! precipitate & ! =mation ( l>g] cry/als1 & may !re=e be sub/itut$ = dige/ion 9 ! cold4 ,! /irr+-rod mu/ n be all[$ to scrat* ! glass1 z ! cry/als adh]e to su* scrat*es & are remov$ ) difficulty4 ,,reprecipitation ,,& ,,ignition ,,( ,,magnesium ,,ammonium ,,phosphate ,a s+le precipitation ( ! magnesium comp\nd 9 ! pres5ce ( molybd5um comp\nds r>ely yields a pure product4 ,! molybd5um c be remov$ by solution ( ! precipitate 9 acid & precipitation ( ! molybd5um by sulphuret$ hydrog51 aft] :i* ! magnesium precipitate may be aga9 ?r[n d[n4 ,x is usually m satisfactory to dissolve ! magnesium precipitate & reprecipitate ! phosphate z magnesium ammonium phosphate z describ$ bel[4 ,,proc$ure4--,dissolve ! precipitate f ! filt] 9 a little dilute hydro*loric acid 7sp4 gr4 #a4ab71 all[+ ! acid solution to run into ! beak] 9 :i* ! orig9al precipitation 0 made 7,note #a74 ,wa% ! filt] ) wat] until ! wa%-wat] %[s no te/ = *lorides1 b avoid an unnecess>y am\nt ( wa%-wat]4 ,add to ! solution #b cc4 7n m7 ( magnesia mixture1 & !n dilute ammonium hydroxide solution 7sp4 gr4 #j4if71 drop by drop1 ) con/ant /irr+1 until ! liquid smells di/9ctly ( ammonia4 ,/ir = a few mom5ts & !n add a volume ( /rong ammonia 7sp4 gr4 #j4ij71 equal to "o ?ird ( ! volume ( ! solution4 ,all[ ! solution to /& = "s h\rs1 & !n filt] (f ! magnesium ammonium phosphate1 :i* %\ld be di/9ctly cry/all9e 9 "*4 ,wa% ! precipitate ) dilute ammonia wat]1 z prescrib$ above1 until1 f9ally1 #c cc4 ( ! wa%+s1 aft] acidify+ ) nitric acid1 %[ no evid5ce ( *lorides4 ,te/ bo? filtrates = complete precipitation by add+ a few cubic c5timet]s ( magnesia mixture & all[+ !m to /& = "s "t4 ,transf] ! moi/ precipitate to a weigh$ porcela9 or plat9um crucible & ignite1 us+ great c>e to raise ! temp]ature sl[ly :ile dry+ ! filt] 9 ! crucible1 & to insure ! ready access ( oxyg5 dur+ ! combu/ion ( ! filt] pap]1 ?us gu>d+ aga9/ a possible r$uction ( ! phosphate1 :i* w\ld result 9 disa/r\s consequ5ces bo? to ! crucible1 if ( plat9um1 & ! analysis4 ,d n raise ! temp]ature above mod]ate r$ness until ! precipitate is :ite4 7,keep ?is precaution well 9 m9d47 ,ignite f9ally at ! highe/ temp]ature ( ! ,tirrill burn]1 & repeat ! heat+ until ! weight is con/ant4 ,if ! ignit$ precipitate is p]si/5tly discolor$ by p>ticles ( unburn$ c>bon1 moi/5 ! mass ) a drop or two ( conc5trat$ nitric acid & heat cauti\sly1 f9ally ignit+ /rongly4 ,! acid w dissolve magnesium pyrophosphate f ! surface ( ! p>ticles ( c>bon1 :i* w !n burn away4 ,nitric acid also aids z an oxidiz+ ag5t 9 supply+ oxyg5 = ! combu/ion ( ! c>bon4 ,f ! weight ( magnesium pyrophosphate 7,mg#b,p#b,o#g7 obta9$1 calculate ! phosphoric anhydride 7,p#b,o#e7 9 ! sample ( apatite4 ,note #a3 ,! ionic *ange involv$ 9 ! precipitation ( ! magnesium comp\nd is ,,po#d--- ,,nh#d ,mg -- ,mg,n,h#d,,po#d4 ,! magnesium ammonium phosphate is readily dissolv$ by acids1 ev5 ^? :i* are no /rong] ?an acetic acid4 ,?is is acc\nt$ = by ! fact t two ( ! ions into :i* phosphoric acid may dissociate1 ! ,,hpo#d-- or ,h#b,,po#d- ions1 exhibit ! *>act]i/ics ( v weak acids1 9 t !y %[ almo/ no t5d5cy to dissociate fur!r into ,h & ,,po#d-- ions4 ,consequ5tly ! ionic *anges :i* occur :5 ! magnesium ammonium phosphate is br\ght into contact ) an acid may be typifi$ by ! reaction3 ,h ,mg ,,nh#d ,,po#d--- -- ,mg ,,nh#d ,,hpo#d--2 t is1 ! ,,po#d-- ions & ! ,h ions lose _! id5tity 9 ! =mation ( ! new ion1 ,,hpo#d--1 & ?is cont9ues until ! magnesium ammonium phosphate is entirely dissolv$4 ,note #b3 ,dur+ ignition ! magnesium ammonium phosphate loses ammonia & wat] & is conv]t$ into magnesium pyrophosphate3 #b,mg,n,h#d,,po#d -- ,mg#b,p#b,o#g #b,,nh#c ,h#b,o4 ,! precautions m5tion$ on pages #aaa & #abc mu/ be obs]v$ ) great c>e dur+ ! ignition ( ?is precipitate4 ,! dang] "h lies 9 a possible r$uction ( ! phosphate by ! c>bon ( ! filt] pap]1 or by ! ammonia evolv$1 :i* may act z a r$uc+ ag5t4 ,! phosphorus !n attacks & injures a plat9um crucible1 & ! det]m9ation is valueless4 ,,analysis ,,( ,,lime/one ,lime/ones v>y widely 9 composition f a ne>ly pure m>ble ?r\gh ! dolomitic lime/ones1 conta9+ v>y+ am\nts ( magnesium1 to ! impure v>ieties1 :i* conta9 also f]r\s & mangan\s c>bonates & silice\s comp\nds 9 v>iable proportions4 ,_m o!r m9]als may be inclos$ 9 lime/ones 9 small quantities1 & an exact qualitative analysis w (t5 %[ ! pres5ce ( sulphides or sulphates1 phosphates1 & titanates1 & ! alkali or ev5 ! heavy metals4 ,no attempt is made 9 ! foll[+ proc$ures to provide a complete quantitative s*eme :i* w\ld take into acc\nt all ( ^! con/itu5ts4 ,su* a s*eme = a complete analysis ( a lime/one may be f\nd 9 ,bullet9 ,no4 #gjj ( ! ,unit$ ,/ates ,geological ,survey4 ,x is assum$ t1 = ^! practice det]m9ations1 a lime/one is select$ :i* conta9s only ! m common con/itu5ts fir/ enum]at$ above4 ,,det]m9ation ,,( ,,moi/ure ,! det]m9ation ( ! am\nt ( moi/ure 9 m9]als or ores is (t5 ( great importance4 ,ores :i* h be5 expos$ to ! wea!r dur+ %ipm5t may h absorb$ en\gh moi/ure to appreciably affect ! results ( analysis4 ,s9ce x is ess5tial t ! sell] & buy] %\ld make _! analyses ^u comp>able mat]ial1 x is cu/om>y = ea* analy/ to det]m9e ! moi/ure 9 ! sample exam9$1 & !n to calculate ! p]c5tages ( ! v>i\s con/itu5ts ) ref]5ce to a sample dri$ 9 ! air1 or at a temp]ature a little above #ajj;,c41 :i*1 unless ! ore has und]gone *emical *ange because ( ! wett+1 %\ld be ! same be=e & aft] %ipm5t4 ,,proc$ure4--,spread #be grams ( ! p[d]$ sample on a weigh$ wat*-glass2 weigh to ! ne>e/ #aj milligrams only & heat at #aje;,c42 weigh at int]vals ( an h\r1 aft] cool+ 9 a desiccator1 until ! loss ( weight aft] an h\r's heat+ does n exce$ #aj milligrams4 ,x %\ld be not$ t a v>iation 9 weight ( #aj milligrams 9 a total weight ( #be grams is no great] relatively ?an a v>iation ( #j4a milligram :5 ! sample tak5 weighs #j4be gram ,,det]m9ation ,,( ,,! ,,insoluble ,,matt] ,,& ,,silica ,,proc$ure4--,weigh out two portions ( ! orig9al p[d]$ sample 7n ! dri$ sample71 ( ab\t #e grams ea*1 into #bej cc4 cass]oles1 & cov] ea* ) a wat*-glass 7,note #a74 ,p\r ov] ! p[d] #be cc4 ( wat]1 & !n add #ej cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab7 9 small portions1 w>m+ g5tly1 until no?+ fur!r appe>s to dissolve 7,note #b74 ,evaporate to dryness on ! wat] ba?4 ,p\r ov] ! residue a mixture ( #e cc4 ( wat] & #e cc4 ( conc5trat$ hydro*loric acid 7sp4 gr4 #a4b7 & aga9 evaporate to dryness1 & f9ally heat = at lea/ an h\r at a temp]ature ( #aaj;,c4 ,p\r ov] ?is residue #ej cc4 ( dilute hydro*loric acid 7"o volume acid 7sp4 gr4 #a4ab7 to five volumes wat]71 & boil = ab\t five m9utes2 !n filt] & wa% twice ) ! dilute hydro*loric acid1 & !n ) hot wat] until free f *lorides4 ,transf] ! filt] & cont5ts to a porcela9 crucible1 dry c>efully ov] a l[ flame1 & ignite to con/ant weight4 ,! residue repres5ts ! insoluble matt] & ! silica f any soluble silicates 7,note #c74 ,calculate ! comb9$ p]c5tage ( ^! 9 ! lime/one4 ,note #a3 ,! relatively l>ge weight 7#e grams7 tak5 = analysis insures great] accuracy 9 ! det]m9ation ( ! +r$i5ts :i* are pres5t 9 small proportions1 & is also m likely to be a repres5tative sample ( ! mat]ial analyz$4 ,note #b3 ,x is pla9 t ! am\nt ( ! insoluble residue & also its "* w (t5 dep5d ^u ! /r5g? ( acid us$ = solution ( ! lime/one4 ,x _c1 !re=e1 be reg>d$ z repres5t+ any well-def9$ con/itu5t1 & its det]m9ation is ess5tially empirical4 ,note #c3 ,x is probable t "s ( ! silicates pres5t are :olly or p>tly decompos$ by ! acid1 & ! soluble silicic acid mu/ be conv]t$ by evaporation to dryness1 & heat+1 into :ite1 insoluble silica4 ,?is *ange is n complete aft] "o evaporation4 ,! heat+ at a temp]ature some:at high] ?an t ( ! wat] ba? = a %ort "t t5ds to leave ! silica 9 ! =m ( a p[d]1 :i* promotes subsequ5t filtration4 ,! silice\s residue is wa%$ fir/ ) dilute acid to prev5t hydrolytic *anges1 :i* w\ld result 9 ! =mation ( appreciable quantities ( insoluble basic iron or alum9ium salts on ! filt] :5 wa%+ ) hot wat]4 ,if x is desir$ to det]m9e ! p]c5tage ( silica sep>ately1 ! ignit$ residue %\ld be mix$ 9 a plat9um crucible ) ab\t six times its weight ( anhydr\s sodium c>bonate1 & ! proc$ure giv5 on page #aea %\ld be foll[$4 ,! filtrate f ! silica is !n add$ to ! ma9 filtrate f ! insoluble residue4 ,,det]m9ation ,,( ,,f]ric ,,oxide ,,& ,,alum9ium ,,oxide 7,,) ,,manganese7 ,,proc$ure4--,to ! filtrate f ! insoluble residue add ammonium hydroxide until ! solution j smells di/9ctly ( ammonia1 b d n add an excess4 ,!n add #e cc4 ( saturat$ brom9e wat] 7,note #a71 & boil = five m9utes4 ,if ! smell ( ammonia has disappe>$1 aga9 add ammonium hydroxide 9 slight excess1 & #c cc4 ( brom9e wat]1 & heat aga9 = a few m9utes4 ,f9ally add #aj cc4 ( ammonium *loride solution & keep ! solution w>m until x b>ely smells ( ammonia2 !n filt] promptly 7,note #b74 ,wa% ! filt] twice ) hot wat]1 !n 7aft] replac+ ! receiv+ beak]7 p\r ?r\gh x #be cc4 ( hot1 dilute hydro*loric acid 7"o volume dilute ,h,cl sp4 gr4 #a4ab to five volumes wat]74 ,a br[n residue insoluble 9 ! acid may be all[$ to rema9 on ! filt]4 ,wa% ! filt] five times ) hot wat]1 add to ! filtrate ammonium hydroxide & brom9e wat] z describ$ above1 & repeat ! precipitation4 ,collect ! precipitate on ! filt] already us$1 wa% x free f *lorides ) hot wat]1 & ignite & weigh z describ$ = f]ric hydroxide on page #aaj4 ,! residue aft] ignition consi/s ( f]ric oxide1 alum9a1 & mangano-manganic oxide 7,mn#c,o#d71 if manganese is pres5t4 ,^! are commonly det]m9$ toge!r 7,note #c74 ,calculate ! p]c5tage ( ! comb9$ oxides 9 ! lime/one4 ,note #a3 ,! addition ( brom9e wat] to ! ammoniacal solutions s]ves to oxidize any f]r\s hydroxide to f]ric hydroxide & to precipitate manganese z ,mn,o7,,oh7#b4 ,! solution mu/ conta9 n m ?an a b>e excess ( hydroxyl ions 7ammonium hydroxide7 :5 x is filt]$1 on acc\nt ( ! t5d5cy ( ! alum9ium hydroxide to r$issolve4 ,! solution %\ld n be /rongly ammoniacal :5 ! brom9e is add$1 z /rong ammonia reacts ) ! brom9e1 ) ! evolution ( nitrog54 ,note #b3 ,! precipitate produc$ by ammonium hydroxide & brom9e %\ld be filt]$ (f promptly1 s9ce ! alkal9e solution absorbs c>bon dioxide f ! air1 ) consequ5t p>tial precipitation ( ! calcium z c>bonate4 ,?is is possible ev5 "u ! mo/ favorable conditions1 & = ?is reason ! iron precipitate is r$issolv$ & aga9 precipitat$ to free x f calcium4 ,:5 ! precipitate is small1 ?is reprecipitation may be omitt$4 ,note #c3 ,9 ! abs5ce ( significant am\nts ( manganese ! iron & alum9ium may be sep>ately det]m9$ by fusion ( ! mix$ ignit$ precipitate1 aft] weigh+1 ) ab\t t5 times its weight ( acid potassium sulphate1 solution ( ! cold fus$ mass 9 wat]1 & volumetric det]m9ation ( ! iron1 z describ$ on page #ff4 ,! alum9ium is !n det]m9$ by diff]5ce1 aft] subtract+ ! weight ( f]ric oxide correspond+ to ! am\nt ( iron f\nd4 ,if a sep>ate det]m9ation ( ! iron1 alum9ium1 & manganese is desir$1 ! mix$ precipitate may be dissolv$ 9 acid be=e ignition1 & ! sep>ation effect$ by special me?ods 7see1 = example1 ,fay1 6,quantitative ,analyses61 ,fir/ ,edition1 pp4 #ae-ai & #bc-bg74 ,,det]m9ation ,,( ,,calcium ,,proc$ure4--,to ! comb9$ filtrates f ! d\ble precipitation ( ! hydroxides j describ$1 add #e cc4 ( dilute ammonium hydroxide 7sp4 gr4 #j4if71 & transf] ! liquid to a #ejj cc4 graduat$ flask1 wa%+ out ! beak] c>efully4 ,cool to laboratory temp]ature1 & fill ! flask ) di/ill$ wat] until ! l[e/ po9t ( ! m5iscus is exactly level ) ! m>k on ! neck ( ! flask4 ,c>efully remove any drops ( wat] :i* are on ! inside ( ! neck ( ! flask above ! graduation by means ( a /rip ( filt] pap]1 make ! solution uni=m by p\r+ x out into a dry beak] & back into ! flask sev]al times4 ,measure (f "o fif? ( ?is solution z foll[s 7,note #a73 ,p\r into a #ajj cc4 graduat$ flask ab\t #aj cc4 ( ! solution1 %ake ! liquid ?or\ghly ov] ! inn] surface ( ! small flask1 & p\r x out4 ,repeat ! same op]ation4 ,fill ! #ajj cc4 flask until ! l[e/ po9t ( ! m5iscus is exactly level ) ! m>k on its neck1 remove any drops ( solution f ! upp] "p ( ! neck ) filt] pap]1 & p\r ! solution into a beak] 7#djj-ejj cc474 ,wa% out ! flask ) small quantities ( wat] until x is clean1 add+ ^! to ! #ajj cc4 ( solution4 ,:5 ! duplicate portion ( #ajj cc4 is measur$ out f ! solution1 rememb] t ! flask mu/ be r9s$ out twice ) t solution1 z prescrib$ above1 be=e ! measurem5t is made4 7,a #ajj cc4 pipette may be us$ to measure out ! aliquot portions1 if pref]r$47 ,dilute ea* ( ! measur$ portions to #bej cc4 ) di/ill$ wat]1 heat ! :ole to boil+1 & add ammonium oxalate solution sl[ly 9 mod]ate excess1 /irr+ well4 ,boil = two m9utes2 all[ ! precipitat$ calcium oxalate to settle = a half-h\r1 & decant ?r\gh a filt]4 ,te/ ! filtrate = complete precipitation by add+ a few cubic c5timet]s ( ! precipitant1 all[+ x to /& = fifte5 m9utes4 ,if no precipitate =ms1 make ! solution slightly acid ) hydro*loric acid 7,note #b72 see t x is prop]ly label$ & res]ve x to be comb9$ ) ! filtrate f ! second calcium oxalate precipitation 7,notes #c & #d74 ,r$issolve ! calcium oxalate 9 ! beak] ) w>m hydro*loric acid1 p\r+ ! acid ?r\gh ! filt]4 ,wa% ! filt] five times ) wat]1 & f9ally p\r ?r\gh x aque\s ammonia4 ,dilute ! solution to #bej cc41 br+ to boil+1 & add #a cc4 ammonium oxalate solution 7,note #e7 & ammonia 9 slight excess2 boil = two m9utes1 & set aside = a half-h\r4 ,filt] (f ! calcium oxalate ^u ! filt] fir/ us$1 & wa% free f *lorides4 ,! filtrate %\ld be made b>ely acid ) hydro*loric acid & comb9$ ) ! filtrate f ! fir/ precipitation4 ,beg9 at once ! evaporation ( ! solutions = ! det]m9ation ( magnesium z describ$ bel[4 ,! precipitate ( calcium oxalate may be conv]t$ into calcium oxide by ignition )\t previ\s dry+4 ,aft] burn+ ! filt]1 x may be ignit$ = ?ree qu>t]s ( an h\r 9 a plat9um crucible at ! highe/ heat ( ! ,buns5 or ,tirrill burn]1 & f9ally = t5 m9utes at ! bla/ lamp 7,note #f74 ,repeat ! heat+ ov] ! bla/ lamp until ! weight is con/ant4 ,z ! calcium oxide absorbs moi/ure f ! air1 x mu/ 7aft] cool+7 be weigh$ z rapidly z possible4 ,! precipitate may1 if pref]r$1 be plac$ 9 a weight$ porcela9 crucible4 ,aft] burn+ (f ! filt] & heat+ = t5 m9utes ! calcium precipitate may be conv]t$ into calcium sulphate by plac+ #b cc4 ( dilute sulphuric acid 9 ! crucible 7cold71 heat+ ! cov]$ crucible v cauti\sly ov] a l[ flame to drive (f ! excess ( acid1 & f9ally at r$ness to con/ant weight 7,note #g74 ,f ! weight ( ! oxide or sulphate1 calculate ! p]c5tage ( ! calcium 7,ca7 9 ! lime/one1 rememb]+ t only "o fif? ( ! total solution is us$ = ?is det]m9ation4 ,note #a3 ,if ! calcium 7 precipitat$ f ! entire solution1 ! quantity ( ! precipitate w\ld be great] ?an c\ld be prop]ly treat$4 ,! solution is1 !re=e1 dilut$ to a def9ite volume 7#ejj cc471 & exactly "o fif? 7#ajj cc47 is measur$ (f 9 a graduat$ flask or by means ( a pipette4 ,note #b3 ,! filtrate f ! calcium oxalate %\ld be made slightly acid imm$iately aft] filtration1 9 ord] to avoid ! solv5t action ( ! alkal9e liquid ^u ! glass4 ,note #c3 ,! accurate quantitative sep>ation ( calcium & magnesium z oxalates requires consid]able c>e4 ,! calcium precipitate usually c>ries d[n ) x "s magnesium1 & ?is c be/ be remov$ by r$issolv+ ! precipitate aft] filtration1 & reprecipitation 9 ! pres5ce ( only ! small am\nt ( magnesium :i* 0 includ$ 9 ! fir/ precipitate4 ,:51 h[ev]1 ! proportion ( magnesium is n v l>ge1 ! second precipitation ( ! calcium c usually be avoid$ by precipitat+ x f a r dilute solution 7#hjj cc4 or s7 & 9 ! pres5ce ( a consid]able excess ( ! precipitant1 t is1 r m ?an en\gh to conv]t bo? ! magnesium & calcium into oxalates4 ,note #d3 ,! ionic *anges involv$ 9 ! precipitation ( calcium z oxalate are exce$+ly simple1 & ! pr9ciples discuss$ 9 connection ) ! b>ium sulphate precipitation on page #aac also apply "h4 ,! reaction is ,c#b,o#d-- ,ca -- ,ca,c#b,o#d4 ,calcium oxalate is ne>ly insoluble 9 wat]1 & only v slightly soluble 9 acetic acid1 b is readily dissolv$ by ! /rong m9]al acids4 ,?is behavior ) acids is expla9$ by ! fact t oxalic acid is a /rong] acid ?an acetic acid2 :51 !re=e1 ! oxalate is br\ght into contact ) ! latt] !re is almo/ no t5d5cy to dim9i% ! conc5tration ( ,c#b,o#d-- ions by ! =mation ( an acid less dissociat$ ?an ! acetic acid itself1 & practically no solv5t action ensues4 ,:5 a /rong m9]al acid is pres5t1 h[ev]1 ! ionization ( ! oxalic acid is mu* r$uc$ by ! high conc5tration ( ! ,h ions f ! /rong acid1 ! =mation ( ! undissociat$ acid less5s ! conc5tration ( ! ,c#b,o#d-- ions 9 solution1 m ( ! oxalate passes into solution to re-e/abli% equilibrium1 & ?is process repeats itself until all is dissolv$4 ,! oxalate is imm$iately reprecipitat$ f su* a solution on ! addition ( ,,oh- ions1 :i*1 by unit+ ) ! ,h ions ( ! acids 7bo? ! m9]al acid & ! oxalic acid7 to =m wat]1 leave ! ,ca & ,c#b,o#d-- ions 9 ! solution to recomb9e to =m ,ca,c#b,o#d1 :i* is precipitat$ 9 ! abs5ce ( ! ,h ions4 ,x is well at ?is po9t to add a small excess ( ,c#b,o#d-- ions 9 ! =m ( ammonium oxalate to decrease ! solubility ( ! precipitate4 ,! oxalate precipitate consi/s ma9ly ( ,ca,c#b,o#d4;,h#b,o :5 ?r[n d[n4 ,note #e3 ,! small quantity ( ammonium oxalate solution is add$ be=e ! second precipitation ( ! calcium oxalate to insure ! pres5ce ( a slight excess ( ! reag5t1 :i* promotes ! sep>ation ( ! calcium comp\nd4 ,note #f3 ,on ignition ! calcium oxalate loses c>bon dioxide & c>bon monoxide1 leav+ calcium oxide3 ,ca,c#b,o#d4;,h#b,o -- ,ca,o ,,co#b ,,co ,h#b,o4 ,= small weights ( ! oxalate 7#j4f gram or less7 ?is reaction may be br\ght ab\t 9 a plat9um crucible at ! highe/ temp]ature ( a ,tirrill burn]1 b x is well to ignite l>g] quantities ?an ?is ov] ! bla/ lamp until ! weight is con/ant4 ,note #g3 ,! heat requir$ to burn ! filt]1 & t subsequ5tly appli$ z describ$1 w conv]t mo/ ( ! calcium oxalate to calcium c>bonate1 :i* is *ang$ to sulphate by ! sulphuric acid4 ,! reactions involv$ are ,ca,c#b,o#d -- ,ca,c,o#c ,,co1 ,ca,c,o#c ,h#b,,s#d -- ,ca,s,o#d ,h#b,o ,,co#b4 ,if a porcela9 crucible is employ$ = ignition1 ?is conv]sion to sulphate is to be pref]r$1 z a complete conv]sion to oxide is difficult to accompli%4 ,note #h3 ,! det]m9ation ( ! calcium may be complet$ volumetrically by wa%+ ! calcium oxalate precipitate f ! filt] into dilute sulphuric acid1 w>m+1 & titrat+ ! lib]at$ oxalic acid ) a /&>d solution ( potassium p]manganate z describ$ on page #gb4 ,:5 a consid]able numb] ( analyses are to be made1 ?is proc$ure w save mu* ( ! "t o!rwise requir$ = ignition & weigh+4 ,,det]m9ation ,,( ,,magnesium ,,proc$ure4--,evaporate ! acidifi$ filtrates f ! calcium precipitates until ! salts beg9 to cry/allize1 b d 6n6 evaporate to dryness 7,note #a74 ,dilute ! solution cauti\sly until ! salts are br\ght into solution1 add+ a little acid if ! solution has evaporat$ to v small volume4 ,! solution %\ld be c>efully exam9$ at ?is po9t & mu/ be filt]$ if a precipitate has appe>$4 ,heat ! cle> solution to boil+2 remove ! burn] & add #be cc4 ( a solution ( disodium phosphate4 ,!n add sl[ly dilute ammonia 7#a volume /rong ammonia 7sp4 gr4 #j4ij7 & #i volumes wat]7 z long z a precipitate cont9ues to =m4 ,f9ally1 add a volume ( conc5trat$ ammonia 7sp4 gr4 #j4ij7 equal to "o ?ird ( ! volume ( ! solution1 & all[ ! :ole to /& = ab\t twelve h\rs4 ,decant ! solution ?r\gh a filt]1 wa% x ) dilute ammonia wat]1 proce$+ z prescrib$ = ! det]m9ation ( phosphoric anhydride on page #abb1 includ+2 ! reprecipitation 7,note #b71 except t #c cc4 ( disodium phosphate solution are add$ be=e ! reprecipitation ( ! magnesium ammonium phosphate in/ead ( ! magnesia mixture !re prescrib$4 ,f ! weight ( ! pyrophosphate1 calculate ! p]c5tage ( magnesium oxide 7,mg,o7 9 ! sample ( lime/one4 ,rememb] t ! pyrophosphate f9ally obta9$ is f "o fif? ( ! orig9al sample4 ,note #a3 ,! precipitation ( ! magnesium %\ld be made 9 z small volume z possible1 & ! ratio ( ammonia to ! total volume ( solution %\ld be c>efully provid$ =1 on acc\nt ( ! relative solubility ( ! magnesium ammonium phosphate4 ,?is matt] has be5 fully discuss$ 9 connection ) ! phosphoric anhydride det]m9ation4 ,note #b3 ,! fir/ magnesium ammonium phosphate precipitate is r>ely :olly cry/all9e1 z x %\ld be1 & is n always ( ! prop] composition :5 precipitat$ 9 ! pres5ce ( su* l>ge am\nts ( ammonium salts4 ,! difficulty c be/ be rem$i$ by filt]+ ! precipitate & 7)\t wa%+ x7 r$issolv+ 9 a small quantity ( hydro*loric acid1 f :i* x may be aga9 ?r[n d[n by ammonia aft] add+ a little disodium phosphate solution4 ,if ! floccul5t "* 0 occasion$ by ! pres5ce ( magnesium hydroxide1 ! second precipitation1 9 a small] volume conta9+ few] salts1 w (t5 result m favorably4 ,! removal ( iron or alum9a f a contam9at$ precipitate is a matt] involv+ a long proc$ure1 & a r$et]m9ation ( ! magnesium f a new sample1 ) additional precautions1 is usually to be pref]r$4 ,,det]m9ation ,,( ,,c>bon ,,dioxide 6,absorption ,app>atus6 ,illu/ration3 ,fig4 #c ,! app>atus requir$ = ! det]m9ation ( ! c>bon dioxide %\ld be arrang$ z %[n 9 ! cut 7,fig4 #c74 ,! flask 7,a7 is an ord9>y wa% bottle1 :i* %\ld be ne>ly fill$ ) dilute hydro*loric acid 7#ajj cc4 acid 7sp4 gr4 #a4ab7 & #bjj cc4 ( wat]74 ,! flask is connect$ by rubb] tub+ 7a7 ) ! glass tube 7b7 lead+ ne>ly to ! bottom ( ! evolution flask 7,b7 & hav+ its l[] end b5t upw>d & drawn out to small bore1 s t ! c>bon dioxide evolv$ f ! lime/one _c bubble back into 7b74 ,! evolution flask %\ld pref]ably be a wide-m\!d ,soxhlet extraction flask ( ab\t #aej cc4 capacity because ( ! ease ) :i* tubes & /opp]s may be fitt$ into ! neck ( a flask ( ?is type4 ,! flask %\ld be fitt$ ) a two-hole rubb] /opp]4 ,! cond5s] 7,c7 may consi/ ( a tube ) two or ?ree l>ge bulbs bl[n 9 x1 = use z an air-cool$ cond5s]1 or x may be a small wat]-jacket$ cond5s]4 ,! latt] is to be pref]r$ if a numb] ( det]m9ations are to be made 9 succession4 ,a glass deliv]y tube 7c7 leads f ! cond5s] to ! small ,u-tube 7,d7 conta9+ "s glass beads or small pieces ( glass rod & #c cc4 ( a saturat$ solution ( silv] sulphate1 ) #c cc4 ( conc5trat$ sulphuric acid 7sp4 gr4 #a4hd74 ,! %ort rubb] tub+ 7d7 connects ! fir/ ,u-tube to a second ,u-tube 7,e7 :i* is fill$ ) small du/-free lumps ( dry calcium *loride1 ) a small1 loose plug ( cotton at ! top ( ea* arm4 ,bo? tubes %\ld be clos$ by cork /opp]s1 ! tops ( :i* are cut (f level )1 or pref]ably =c$ a little bel[1 ! top ( ! ,u-tube1 & !n neatly seal$ ) seal+ wax4 ,! c>bon dioxide may be absorb$ 9 a tube conta9+ soda lime 7,f7 or 9 a ,geissl] bulb 7,f'7 conta9+ a conc5trat$ solution ( potassium hydroxide 7,note #b74 ,! tube 7,f7 is a glass-/opp]$ side-arm ,u-tube 9 :i* ! side t[>d ! evolution flask & "o half ( ! o!r side are fill$ ) small1 du/-free lumps ( soda lime ( good quality 7,note #c74 ,s9ce soda lime conta9s consid]able moi/ure1 ! o!r half ( ! "r side ( ! tube is fill$ ) small lumps ( dry1 du/-free calcium *loride to reta9 ! moi/ure f ! soda lime4 ,loose plugs ( cotton are plac$ at ! top ( ea* arm & betwe5 ! soda lime & ! calcium *loride4 ,! ,geissl] bulb 7,f'71 if us$1 %\ld be fill$ ) potassium hydroxide solution 7#a "p ( solid potassium hydroxide dissolv$ 9 two p>ts ( wat]7 until ea* small bulb is ab\t two ?irds full 7,note #d74 ,a small tube conta9+ calcium *loride is connect$ ) ! ,geissl] bulb prop] by a gr\nd jo9t & %\ld be wir$ to ! bulb = safety4 ,?is is design$ to reta9 any moi/ure f ! hydroxide solution4 ,a piece ( clean1 f9e copp] wire is s atta*$ to ! bulb t x c be hung f ! hook above a balance pan1 or o!r support4 ,! small bottle 7,g7 ) conc5trat$ sulphuric acid 7sp4 gr4 #a4hd7 is s arrang$ t ! tube 7f7 b>ely dips bel[ ! surface4 ,?is w prev5t ! absorption ( wat] vapor by 7,f7 or 7,f'7 & s]ves z an aid 9 regulat+ ! fl[ ( air ?r\gh ! app>atus4 7,h7 is an aspirator bottle ( ab\t f\r lit]s capacity1 fill$ ) wat]2 7k7 is a safety tube & a means ( refill+ 7,h72 7h7 is a screw clamp1 & 7,k7 a ,u-tube fill$ ) soda lime4 ,note #a3 ,! air curr5t1 :i* is subsequ5tly drawn ?r\gh ! app>atus1 to sweep all ( ! c>bon dioxide into ! absorption app>atus1 is likely to c>ry ) x "s hydro*loric acid f ! evolution flask4 ,?is acid is reta9$ by ! silv] sulphate solution4 ,! addition ( conc5trat$ sulphuric acid to ?is solution r$uces its vapor pressure s f> t v little wat] is c>ri$ on by ! air curr5t1 & ?is slight am\nt is absorb$ by ! calcium *loride 9 7,e74 ,z ! calcium *loride frequ5tly conta9s a small am\nt ( a basic mat]ial :i* w\ld absorb c>bon dioxide1 x is necess>y to pass c>bon dioxide ?r\gh 7,e7 = a %ort "t & !n drive all ! gas out ) a dry air curr5t = ?irty m9utes be=e use4 ,note #b3 ,soda-lime absorption tubes are to be pref]r$ if a satisfactory quality ( soda lime is available & ! numb] ( det]m9ations to be made successively is small4 ,! pota% bulbs w usually p]mit ( a l>g] numb] ( successive det]m9ations )\t refill+1 b !y require great] c>e 9 h&l+ & 9 ! analytical proc$ure4 ,note #c3 ,soda lime is a mixture ( sodium & calcium hydroxides4 ,bo? comb9e ) c>bon dioxide to =m c>bonates1 ) ! evolution ( wat]4 ,consid]able heat is g5]at$ by ! reaction1 & ! temp]ature ( ! tube dur+ absorption s]ves z a r\gh index ( ! progress ( ! reaction ?r\gh ! mass ( soda lime4 ,x is ess5tial t soda lime ( good quality = analytical purposes %\ld be us$4 ,! tube %\ld n conta9 du/1 z ?is is likely to be swept away4 ,note #d3 ,! solution ( ! hydroxide = use 9 ! ,geissl] bulb mu/ be highly conc5trat$ to insure complete absorption ( ! c>bon dioxide & also to r$uce ! vapor pressure ( ! solution1 ?us less5+ ! dang] ( loss ( wat] ) ! air :i* passes ?r\gh ! bulbs4 ,! small quantity ( moi/ure :i* is !n c>ri$ out ( ! bulbs is held by ! calcium *loride 9 ! prolong tube4 ,! be/ =m ( absorption bulb is t to :i* ! prolong tube is atta*$ by a gr\nd glass jo9t4 ,aft] ! potassium hydroxide is approximately half consum$ 9 ! fir/ bulb ( ! absorption app>atus1 potassium bic>bonate is =m$1 & z x is mu* less soluble ?an ! c>bonate1 x (t5 precipitates4 ,its =mation is a w>n+ t ! absorb+ p[] ( ! hydroxide is mu* dim9i%$4 6,! ,analysis6 ,,proc$ure4-- ,weigh out into ! flask 7,b7 ab\t #a gram ( lime/one4 ,cov] x ) #ae cc4 ( wat]4 ,weigh ! absorption app>atus 7,f7 or 7,f'7 accurately aft] all[+ x to /& = #cj m9utes 9 ! balance case1 & wip+ x c>efully ) a l9tless clo?1 tak+ c>e to h&le x z little z possible aft] wip+ 7,note #a74 ,connect ! absorption app>atus ) 7e7 & 7f74 ,if a soda-lime tube is us$1 be sure t ! arm conta9+ ! soda lime is next ! tube 7,e7 & t ! glass /opcocks are op54 ,to be sure t ! :ole app>atus is airtight1 disconnect ! rubb] tube f ! flask 7,a71 mak+ sure t ! tubes 7a7 & 7b7 d n conta9 any hydro*loric acid1 close ! p9*cocks 7a7 & 7k7 & op5 7h74 ,no bubbles %\ld pass ?r\gh 7,d7 or 7,g7 aft] a few seconds4 ,:5 assur$ t ! fitt+s are tight1 close 7h7 & op5 7a7 cauti\sly to admit air to re/ore atmosph]ic pressure4 ,?is precaution is ess5tial1 z a sudd5 inru% ( air w project liquid f 7,d7 or 7,f'74 ,reconnect ! rubb] tube ) ! flask 7,a74 ,op5 ! p9*cocks 7a7 & 7k7 & bl[ ov] ab\t #aj cc4 ( ! hydro*loric acid f 7,a7 into 7,b74 ,:5 ! action ( ! acid slack5s1 bl[ ov] 7sl[ly7 ano!r #aj cc4 ,! rate ( gas evolution %\ld n exce$ = m ?an a few seconds t at :i* ab\t two bubbles p] second pass ?r\gh 7,g7 7,note #b74 ,repeat ! addition ( acid 9 small portions until ! action ^u ! lime/one seems to be at an end1 tak+ c>e to close 7a7 aft] ea* addition ( acid 7,note #c74 ,disconnect 7,a7 & connect ! rubb] tub+ ) ! soda-lime tube 7,k7 & op5 7a74 ,!n close 7k7 & op5 7h71 regulat+ ! fl[ ( wat] f 7,h7 9 su* a way t ab\t two bubbles p] second pass ?r\gh 7,g74 ,place a small flame "u 7,b7 & 6sl[ly6 raise ! cont5ts to boil+ & boil = ?ree m9utes4 ,!n remove ! burn] f "u 7,b7 & cont9ue to draw air ?r\gh ! app>atus = #bj-cj m9utes1 or until 7,h7 is empti$ 7,note #d74 ,remove ! absorption app>atus1 clos+ ! /opcocks on 7,f7 or /opp]+ ! op5 ends ( 7,f'71 leave ! app>atus 9 ! balance case = at lea/ ?irty m9utes1 wipe x c>efully & weigh1 aft] op5+ ! /opcocks 7or remov+ plugs74 ,! increase 9 weight is due to absorption ( ,,co#b1 f :i* its p]c5tage 9 ! sample may be calculat$4 ,aft] clean+ 7,b7 & refill+ 7,h71 ! app>atus is ready = ! duplicate analysis4 ,note #a3 ,! absorption tubes or bulbs h l>ge surfaces on :i* moi/ure may collect4 ,by all[+ !m to rema9 9 ! balance case = "s "t be=e weigh+1 ! am\nt ( moi/ure absorb$ on ! surface is z ne>ly con/ant z practicable dur+ two weigh+s1 & a uni=m temp]ature is also assur$4 ,! /opcocks ( ! ,u-tube %\ld be op5$1 or ! plugs us$ to close ! op5+s ( ! ,geissl] bulb %\ld be remov$ be=e weigh+ 9 ord] t ! air cont5ts %all always be at atmosph]ic pressure4 ,note #b3 ,if ! gas passes too rapidly into ! absorption app>atus1 "s c>bon dioxide may be c>ri$ ?r\gh1 n be+ completely reta9$ by ! absorb5ts4 ,note #c3 ,! ess5tial ionic *anges involv$ 9 ?is proc$ure are ! foll[+3 ,x is assum$ t ! lime/one1 :i* is typifi$ by calcium c>bonate1 is v slightly soluble 9 wat]1 & ! ions result+ are ,ca & ,,co#c--4 ,9 ! pres5ce ( ,h ions ( ! m9]al acid1 ! ,,co#c-- ions =m ,h#b;,,co#c4 ,?is is n only a weak acid :i*1 by its =mation1 dim9i%es ! conc5tration ( ! ,,co#c-- ions1 ?us caus+ m ( ! c>bonate to dissolve to re-e/abli% equilibrium1 b x is also an un/able comp\nd & breaks d[n into c>bon dioxide & wat]4 ,note #d3 ,c>bon dioxide is dissolv$ by cold wat]1 b ! gas is expell$ by boil+1 &1 toge!r ) t :i* is di/ribut$ ?r\gh ! app>atus1 is swept out into ! absorption bulb by ! curr5t ( air4 ,?is air is purifi$ by draw+ x ?r\gh ! tube 7,k7 conta9+ soda lime1 :i* removes any c>bon dioxide :i* may be 9 x4 ,,det]m9ation ,,( ,,lead1 ,,copp]1 ,,iron1 ,,& ,,z9c ,,9 ,,brass ,,electrolytic ,,sep>ations 6,g5]al ,discussion6 ,:5 a direct curr5t ( electricity passes f "o electrode to ano!r ?r\gh solutions ( electrolytes1 ! individual ions pres5t 9 ^! solutions t5d to move t[>d ! electrode ( opposite electrical *>ge to t :i* ea* ion be>s1 & to be dis*>g$ by t electrode4 ,:e!r or n su* dis*>ge actually occurs 9 ! case ( any p>ticul> ion dep5ds ^u ! pot5tial 7voltage7 ( ! curr5t :i* is pass+ ?r\gh ! solution1 s9ce = ea* ion !re is1 "u def9ite conditions1 a m9imum pot5tial bel[ :i* ! dis*>ge ( ! ion _c be effect$4 ,by tak+ advantage ( diff]5ces 9 dis*>ge-pot5tials1 x is possible to effect sep>ations ( a numb] ( ! metallic ions by electrolysis1 & at ! same "t to deposit ! metals 9 =ms :i* admit ( direct weigh+4 ,9 ?is way ! sl[] proc$ures ( precipitation & filtration may frequ5tly be avoid$4 ,! foll[+ p>agraphs pres5t a brief /atem5t ( ! fundam5tal pr9ciples & conditions und]ly+ electro-analysis4 ,! total en]gy ( an electric curr5t z x passes ?r\gh a solution is di/ribut$ among ?ree factors1 fir/1 its pot5tial1 :i* is measur$ 9 volts1 & corresponds to :at is call$ head 9 a /ream ( wat]2 second1 curr5t /r5g?1 :i* is measur$ 9 amp]es1 & corresponds to ! volume ( wat] pass+ a cross-section ( a /ream 9 a giv5 "t int]val2 & ?ird1 ! resi/ance ( ! conduct+ m$ium1 :i* is measur$ 9 ohms4 ,! relation betwe5 ^! ?ree factors is express$ by ,ohm's law1 namely1 t 6,i ,e_/,r61 :5 ,i is curr5t /r5g?1 ,e pot5tial1 & ,r resi/ance4 ,x is pla9 t1 = a con/ant resi/ance1 ! /r5g? ( ! curr5t & its pot5tial are mutually & directly int]dep5d5t4 ,z already /at$1 ! appli$ electrical pot5tial det]m9es :e!r or n deposition ( a metal ^u an electrode actually occurs4 ,! curr5t /r5g? det]m9es ! rate ( deposition & ! physical *>act]i/ics ( ! deposit4 ,! resi/ance ( ! solution is g5]ally s small z to fall out ( practical consid]ation4 ,approximate deposition-pot5tials h be5 det]m9$ = a numb] ( ! metallic elem5ts1 & also = hydrog5 & "s ( ! acid-=m+ radicals4 ,! values giv5 bel[ are ^? requir$ = deposition f normal solutions at ord9>y temp]atures ) ref]5ce to a hydrog5 electrode4 ,!y mu/ be reg>d$ z approximate1 s9ce sev]al di/urb+ factors & "s second>y reactions r5d] difficult _! exact application "u ! conditions ( analysis4 ,!y are3 ,zn ,cd ,fe ,ni ,pb ,h ,cu ,sb ,hg ,ag ,,s#d #j4gg #j4db #j4cd #j4cc #j4ac #j -#j4cd -#j4fg -#j4gf -#j4gi #a4ij ,f ^! data x is evid5t t 9 ord] to deposit copp] f a normal solution ( copp] sulphate a m9imum pot5tial equal to ! algebraic sum ( ! deposition-pot5tials ( copp] ions & sulphate ions mu/ be appli$1 t is1 #a4ef volts4 ,! deposition ( z9c f a solution ( z9c sulphate w\ld require #b4fg volts1 b1 s9ce ! deposition ( hydrog5 f sulphuric acid solution requires only #a4ij volts1 ! quantitative deposition ( z9c by electrolysis f a sulphuric acid solution ( a z9c salt is n practicable4 ,on ! o!r h&1 silv]1 if pres5t 9 a solution ( copp] sulphate1 w\ld deposit ) ! copp]4 ,! =ego+ examples suffice to illu/rate ! application ( ! pr9ciple ( deposition pot5tials1 b x mu/ fur!r be not$ t ! values /at$ apply to normal solutions ( ! comp\nds 9 "q1 t is1 to solutions ( consid]able conc5trations4 ,z ! conc5tration ( ! ions dim9i%es1 & h5ce few] ions approa* ! electrodes1 some:at high] voltages are requir$ to attract & dis*>ge !m4 ,f ?is x foll[s t ! conc5trations %\ld be kept z high z possible to effect complete deposition 9 ! lea/ practicable "t1 or else ! pot5tials appli$ mu/ be progressively increas$ z deposition proce$s4 ,9 practice1 ! desir$ result is obta9$ by />t+ ) small volumes ( solution1 us+ z l>ge an electrode surface z possible1 & by /irr+ ! solution to br+ ! ions 9 contact ) ! electrodes4 ,?is is1 9 g5]al1 a m conv5i5t proc$ure ?an t ( increas+ ! pot5tial ( ! curr5t dur+ electrolysis1 al?\gh t me?od is also us$4 ,z already /at$1 ^? ions 9 a solution ( electrolytes w fir/ be dis*>g$ :i* h ! l[e/ deposition pot5tials1 & s long z ^! ions are pres5t ar\nd ! electrode 9 consid]able conc5tration !y1 almo/ alone1 are dis*>g$1 b1 z _! conc5tration dim9i%es1 o!r ions ^: deposition pot5tials are high] b /ill )9 t ( ! curr5t appli$1 w also beg9 to sep>ate4 ,= example1 f a nitric acid solution ( copp] nitrate1 ! copp] ions w fir/ be dis*>g$ at ! ca?ode1 b z !y dim9i% 9 conc5tration hydrog5 ions f ! acid 7or wat]7 w be also dis*>g$4 ,s9ce ! hydrog5 ?us lib]at$ is a r$uc+ ag5t1 ! nitric acid 9 ! solution is sl[ly r$uc$ to ammonia1 & x may happ5 t if ! curr5t is pass$ ?r\gh = a long "t1 su* a solution w become alkal9e4 ,oxyg5 is lib]at$ at ! anode1 b1 s9ce !re is no oxidizable sub/ance pres5t ar\nd t electrode1 x escapes z oxyg5 gas4 ,x %\ld be not$ t1 9 g5]al1 ! *anges occurr+ at ! ca?ode are r$uctions1 :ile ^? at ! anode are oxidations4 ,= analytical purposes1 solutions ( nitrates or sulphates ( ! metals are pref]able to ^? ( ! *lorides1 s9ce lib]at$ *lor9e attacks ! electrodes4 ,9 "s cases1 z = example1 t ( silv]1 solution ( salts =m+ complex ions1 l t ( ! d\ble cyanide ( silv] & potassium1 yield bett] metallic deposits4 ,mo/ metals are deposit$ z su* ^u ! ca?ode2 a few1 notably lead & manganese1 sep>ate 9 ! =m ( dioxides ^u ! anode4 ,x is evid5tly important t ! deposit$ mat]ial %\ld be s firmly adh]5t t x c be wa%$1 dri$1 & weigh$ )\t loss 9 h&l+4 ,to secure ^! conditions x is ess5tial t ! curr5t d5sity 7t is1 ! am\nt ( curr5t p] unit ( area ( ! electrodes7 %all n be too high4 ,9 prescrib+ analytical conditions x is cu/om>y to /ate ! curr5t /r5g? 9 normal d5sities express$ 9 amp]es p] #ajj sq4 cm4 ( electrode surface1 z1 = example1 ,n4,d#ajj #b amps4 ,if deposition occurs too rapidly1 ! deposit is likely to be spongy or loosely adh]5t & falls (f on subsequ5t treatm5t4 ,?is places a practical limit to ! curr5t d5sity to be employ$1 = a giv5 electrode surface4 ,! cause ( ! unsatisfactory "* ( ! deposit is app>5tly sometimes to be f\nd 9 ! co9cid5t lib]ation ( consid]able hydrog5 & sometimes 9 ! failure ( ! rapidly deposit$ mat]ial to =m a cont9u\s adh]5t surface4 ,! effect ( rotat+ electrodes ^u ! "* ( ! deposit is ref]r$ to bel[4 ,! negative ions ( an electrolyte are attract$ to ! anode & are dis*>g$ on contact ) x4 ,anions su* z ! *loride ion yield *lor9e atoms1 f :i* gase\s *lor9e molecules are =m$ & escape4 ,! radicals :i* compose su* ions z ,,no#c- or ,,s#d-- are n capable ( indep5d5t exi/5ce aft] dis*>ge1 & break d[n into oxyg5 & ,n#b,o#e & ,,s#c respectively4 ,! oxyg5 escapes & ! anhydrides1 react+ ) wat]1 re-=m nitric & sulphuric acids4 ,! law ( ,f>aday expresses ! relation betwe5 curr5t /r5g? & ! quantities ( ! decomposition products :i*1 "u con/ant conditions1 appe> at ! electrodes1 namely1 t a giv5 quantity ( electricity1 act+ = a giv5 "t1 causes ! sep>ation ( *emically equival5t quantities ( ! v>i\s elem5ts or radicals4 ,= example1 s9ce #ajg4id grams ( silv] is equival5t to #a4jjh grams ( hydrog51 & t 9 turn to #h grams ( oxyg51 or #ca4gh grams ( copp]1 ! quantity ( electricity :i* w cause ! deposit ( #ajg4id grams ( silv] 9 a giv5 "t w also sep>ate ! weights j indicat$ ( ! o!r sub/ances4 ,exp]im5ts %[ t a curr5t ( "o amp]e pass+ = "o second1 i4e41 a c\lomb ( electricity1 causes ! deposition ( #j4jjaaah gram ( silv] f a normal solution ( a silv] salt4 ,! numb] ( c\lombs requir$ to deposit #ajg4id grams is #ajg4id_/j4jjaaah or #if1eej & ! same numb] ( c\lombs w also cause ! sep>ation ( #a4jjh grams ( hydrog51 #h grams ( oxyg5 or #ca4gh grams ( copp]4 ,:ile x might at fir/ appe> t ,f>aday's law c\ld ?us be us$ z a basis = ! calculation ( ! "t requir$ = ! deposition ( a giv5 quantity ( an electrolyte f solution1 x mu/ be rememb]$ t ! law expresses :at occurs :5 ! conc5tration ( ! ions 9 ! solution is kept con/ant1 z1 = example1 :5 ! anode 9 a silv] salt solution is a plate ( metallic silv]4 ,"u ! conditions ( electro-analysis ! conc5tration ( ! ions is con/antly dim9i%+ z deposition proce$s & ! "t actually requir$ = complete deposition ( a giv5 weight ( mat]ial by a curr5t ( con/ant /r5g? is1 !re=e1 great] ?an t calculat$ on ! basis ( ! law z /at$ above4 ,! electrodes employ$ 9 electro-analysis are almo/ exclusively ( plat9um1 s9ce t metal alone satisfactorily resi/s *emical action ( ! electrolytes1 & c be dri$ & weigh$ )\t *ange 9 composition4 ,! plat9um electrodes may be us$ 9 ! =m ( di%es1 foil or gauze4 ,! la/1 on acc\nt ( ! ease ( circulation ( ! electrolyte1 its relatively l>ge surface 9 proportion to its weight & ! read9ess ) :i* x c be wa%$ & dri$1 is g5]ally pref]r$4 ,_m devices h be5 describ$ by ! use ( :i* ! electrode ^u :i* deposition occurs c be me*anically rotat$4 ,?is has an effect p>allel to t ( greatly increas+ ! electrode surface & also provides a mo/ effici5t means ( /irr+ ! solution4 ,) su* an app>atus ! amp]age may be increas$ to #e or ev5 #aj amp]es & depositions complet$ ) great rapidity & accuracy4 ,x is desirable1 :5ev] practicable1 to provide a rotat+ or /irr+ device1 s9ce1 = example1 ! "t consum$ 9 ! deposition ( ! am\nt ( copp] usually f\nd 9 analysis may be r$uc$ f ! #bj to #bd h\rs requir$ ) /ation>y electrodes1 & un/irr$ solutions1 to ab\t "o half h\r4 ,,det]m9ation ,,( ,,copp] ,,& ,,lead ,,proc$ure4--,weigh out two portions ( ab\t #j4e gram ea* 7,note #a7 into tall1 sl5d] lipless beak]s ( ab\t #ajj cc4 capacity4 ,dissolve ! metal 9 a solution ( #e cc4 ( dilute nitric acid 7sp4 gr4 #a4bj7 & #e cc4 ( wat]1 heat+ g5tly1 & keep+ ! beak] cov]$4 ,:5 ! sample has all dissolv$ 7,note #b71 wa% d[n ! sides ( ! beak] & ! bottom ( ! wat*-glass ) wat] & dilute ! solution to ab\t #ej cc4 ,c>efully heat to boil+ & boil = a m9ute or two to expel nitr\s fumes4 ,mean:ile1 f\r plat9um electrodes1 two anodes & two ca?odes1 %\ld be clean$ by dipp+ 9 dilute nitric acid1 wa%+ ) wat] & f9ally ) #ie p] c5t alcohol 7,note #c74 ,! alcohol may be ignit$ & burn$ (f4 ,! electrodes are !n cool$ 9 a desiccator & weigh$4 ,connect ! electrodes ) ! b9d+ po/s 7or o!r device = connection ) ! electric circuit7 9 su* a way t ! copp] w be deposit$ ^u ! electrode ) ! l>g] surface1 :i* is made ! ca?ode4 ,! beak] conta9+ ! solution %\ld !n be rais$ into place f bel[ ! electrodes until ! latt] rea* ne>ly to ! bottom ( ! beak]4 ,! support = ! beak] mu/ be s arrang$ t x c be easily rais$ or l[]$4 ,if ! electrolytic app>atus is provid$ ) a me*anism = ! rotation ( ! electrode or /irr+ ( ! electrolyte1 proce$ z foll[s3 ,arrange ! resi/ance 9 ! circuit to provide a direct curr5t ( ab\t "o amp]e4 ,pass ?is curr5t ?r\gh ! solution to be electrolyz$1 & />t ! rotat+ me*anism4 ,keep ! beak] cov]$ z completely z possible1 us+ a split wat*-glass 7or o!r device7 to avoid loss by spatt]+4 ,:5 ! solution is colorless1 :i* is usually ! case aft] ab\t #ce m9utes1 r9se (f ! cov] glass1 wa% d[n ! sides ( ! beak]1 add ab\t #j4cj gram ( urea & cont9ue ! electrolysis = ano!r five m9utes 7,notes #d & #e74 ,if /ation>y electrodes are employ$1 ! curr5t /r5g? %\ld be ab\t #j4a amp]e1 :i* may1 aft] #ab to #ae h\rs1 be increas$ to #j4b amp]e4 ,! "t requir$ = complete deposition is usually f #bj to #bd h\rs4 ,x is advisable to add #e cc4 ( nitric acid 7sp4 gr4 #a4b7 if ! electrolysis ext5ds ov] ?is l5g? ( "t4 ,no urea is add$ 9 ?is case4 ,:5 ! deposition ( ! copp] appe>s to be complete1 /op ! rotat+ me*anism & sl[ly l[] ! beak] ) ! left h&1 direct+ at ! same "t a /ream ( wat] f a wa% bottle on bo? electrodes4 ,remove ! beak]1 %ut (f ! curr5t1 &1 if necess>y1 complete ! wa%+ ( ! electrodes 7,note #f74 ,r9se ! electrodes cauti\sly ) alcohol & heat !m 9 a hot closet until ! alcohol has j evaporat$1 b no long]1 s9ce ! copp] is likely to oxidize at ! high] temp]ature4 7,! alcohol may be remov$ by ignition if c>e is tak5 to keep ! electrodes 9 motion 9 ! air s t ! copp] deposit is n too /rongly heat$ at any "o po9t47 ,te/ ! solution 9 ! beak] = copp] z foll[s1 rememb]+ t x is to be us$ = subsequ5t det]m9ations ( iron & z9c3 ,remove ab\t #e cc4 & add a slight excess ( ammonia4 ,comp>e ! mixture ) "s di/ill$ wat]1 hold+ bo? above a :ite surface4 ,! solution %\ld n %[ any t+e ( blue4 ,if ! pres5ce ( copp] is indicat$1 add ! te/ portion to ! ma9 solution1 evaporate ! :ole to a volume ( ab\t #ajj cc41 & aga9 electrolyze ) clean electrodes 7,note #g74 ,aft] cool+ ! electrodes 9 a desiccator1 weigh !m & f ! weight ( copp] on ! ca?ode & ( lead dioxide 7,pb,o#b7 on ! anode1 calculate ! p]c5tage ( copp] 7,cu7 & ( lead 7,pb7 9 ! brass4 ,note #a3 ,x is obvi\s t ! brass tak5 = analysis %\ld be unt>ni%$1 :i* c be easily assur$1 :5 wire is us$1 by sc\r+ ) em]y4 ,if *ips or bor+s are us$1 !y %\ld be well mix$1 & ! sample = analysis tak5 f diff]5t p>ts ( ! mixture4 ,note #b3 ,if a :ite residue rema9s ^u treatm5t ( ! alloy ) nitric acid1 x indicates ! pres5ce ( t94 ,! mat]ial is n1 !re=e1 a true brass4 ,?is may be treat$ z foll[s3 ,evaporate ! solution to dryness1 moi/5 ! residue ) #e cc4 ( dilute nitric acid 7sp4 gr4 #a4b7 & add #ej cc4 ( hot wat]4 ,filt] (f ! meta-/annic acid1 wa%1 ignite 9 porcela9 & weigh z ,sn,o#b4 ,?is oxide is nev] :olly free f copp] & mu/ be purifi$ = an exact det]m9ation4 ,if x does n exce$ #b p] c5t ( ! alloy1 ! quantity ( copp] :i* x conta9s may usually be neglect$4 ,note #c3 ,! electrodes %\ld be fre$ f all greasy matt] be=e us+1 & ^? portions ^u :i* ! metal w deposit %\ld n be t\*$ ) ! f+]s aft] clean+4 ,note #d3 ,( ! ions 9 solution1 ! ,h1 ,cu1 ,zn1 & ,fe ions t5d to move t[>d ! ca?ode4 ,! ,,no#c- ions & ! lead1 probably 9 ! =m ( ,pb,o#b-- ions1 move t[>d ! anode4 ,at ! ca?ode ! ,cu ions are dis*>g$ & plate out z metallic copp]4 ,?is alone occurs :ile ! solution is relatively conc5trat$4 ,lat] on1 ,h ions are also dis*>g$4 ,9 ! pres5ce ( consid]able quantities ( ,h ions1 z 9 ?is acid solution1 no ,zn or ,fe ions are dis*>g$ because ( _! great] deposition pot5tials4 ,at ! anode ! lead is deposit$ z ,pb,o#b & oxyg5 is evolv$4 ,= ! reasons /at$ on page #ada c>e mu/ be tak5 t ! solution does n become alkal9e if ! electrolysis is long cont9u$4 ,note #e3 ,urea reacts ) nitr\s acid1 :i* may be =m$ 9 ! solution z a result ( ! r$uc+ action ( ! lib]at$ hydrog54 ,its removal promotes ! complete precipitation ( ! copp]4 ,! reaction is ,,co7,,nh#b7b #b;,,hno#b -- ,,co#b #b,n#b #c;,h#b,o4 ,note #f3 ,! electrodes mu/ be wa%$ ne>ly or q free f ! nitric acid solution be=e ! circuit is brok5 to prev5t re-solution ( ! copp]4 ,if sev]al solutions are connect$ 9 ! same circuit x is obvi\s t "s device mu/ be us$ to close ! circuit z soon z ! beak] is remov$4 ,note #g3 ,! electrodes ^u :i* ! copp] has be5 deposit$ may be clean$ by imm]sion 9 w>m nitric acid4 ,to remove ! lead dioxide1 add a few cry/als ( oxalic acid to ! nitric acid4 ,,det]m9ation ,,( ,,iron ,mo/ brasses conta9 small p]c5tages ( iron 7usually n ov] #j4a p] c5t7 :i*1 unless remov$1 is precipitat$ z phosphate & weigh$ ) ! z9c4 ,,proc$ure4--,to ! solution f ! precipitation ( copp] & lead by electrolysis1 add dilute ammonia 7sp4 gr4 #j4if7 until ! precipitate ( z9c hydroxide :i* fir/ =ms re-dissolves1 leav+ only a slight r$ precipitate ( f]ric hydroxide4 ,filt] (f ! iron precipitate1 us+ a wa%$ filt]1 & wa% five times ) hot wat]4 ,te/ a portion ( ! la/ wa%+ ) a dilute solution ( ammonium sulphide to assure complete removal ( ! z9c4 ,! precipitate may !n be ignit$ & weigh$ z f]ric oxide1 z describ$ on page #aaj4 ,calculate ! p]c5tage ( iron 7,fe7 9 ! brass4 ,,det]m9ation ,,( ,,z9c ,,proc$ure4--,acidify ! filtrate f ! iron det]m9ation ) dilute nitric acid4 ,conc5trate x to #aej cc4 ,add to ! cold solution dilute ammonia 7sp4 gr4 #j4if7 cauti\sly until x b>ely smells ( ammonia2 !n add 6"o drop6 ( a dilute solution ( litmus 7,note #a71 & drop 91 ) ! aid ( a dropp]1 dilute nitric acid until ! blue ( ! litmus j *anges to r$4 ,x is important t ?is po9t %\ld n be ov]/epp$4 ,heat ! solution ne>ly to boil+ & p\r into x sl[ly a filt]$ solution ( di-ammonium hydrog5 phosphate#a conta9+ a weight ( ! phosphate ab\t equal to twelve times t ( ! z9c to be precipitat$4 7,= ?is calculation ! approximate p]c5tage ( z9c is t f\nd by subtract+ ! sum ( ! p]c5tages ( ! copp]1 lead & iron f #ajj p] c5t47 ,keep ! solution j bel[ boil+ = fifte5 m9utes1 /irr+ frequ5tly 7,note #b74 ,if at ! end ( ?is "t ! amorph\s precipitate has become cry/all9e1 all[ ! solution to cool = ab\t f\r h\rs1 al?\gh a long] "t does no h>m 7,note #c71 & filt] ^u an asbe/os filt] 9 a porcela9 ,goo* crucible4 ,! filt] is prep>$ z describ$ on page #ajc1 & %\ld be dri$ to con/ant weight at #aje;,c4 ,footnote #a3 ,! ammonium phosphate :i* is commonly obta9able conta9s "s mono-ammonium salt1 & ?is is n satisfactory z a precipitant4 ,x is advisable1 !re=e1 to weigh out ! am\nt ( ! salt requir$1 dissolve x 9 a small volume ( wat]1 add a drop ( ph5olph?ale9 solution1 & f9ally add dilute ammonium hydroxide solution cauti\sly until ! solution j becomes p9k1 b d n add an excess4 ,wa% ! precipitate until free f sulphates ) a w>m #a p] c5t solution ( ! di-ammonium phosphate1 & !n five times ) #ej p] c5t alcohol 7,note #d74 ,dry ! crucible & precipitate = an h\r at #aje;,c41 & f9ally to con/ant weight 7,note #e74 ,! filtrate %\ld be made alkal9e ) ammonia & te/$ = z9c ) a few drops ( ammonium sulphide1 all[+ x to /& 7,notes #f1 #g & #h74 ,f ! weight ( ! z9c ammonium phosphate 7,zn,n,h#d,,po#d7 calculate ! p]c5tage ( ! z9c 7,zn7 9 ! brass4 ,note #a3 ,! z9c ammonium phosphate is soluble bo? 9 acids & 9 ammonia4 ,x is1 !re=e1 necess>y to precipitate ! z9c 9 a ne>ly neutral solution1 :i* is m accurately obta9$ by add+ a drop ( a litmus solution to ! liquid ?an by ! use ( litmus pap]4 ,note #b3 ,! precipitate :i* fir/ =ms is amorph\s1 & may h a v>iable composition4 ,on /&+ x becomes cry/all9e & !n has ! composition ,zn,n,h#d,,po#d4 ,! precipitate !n settles rapidly & is apt to occasion bump+ if ! solution is heat$ to boil+4 ,/irr+ promotes ! cry/allization4 ,note #c3 ,9 a c>efully neutraliz$ solution conta9+ a consid]able excess ( ! precipitant1 & also ammonium salts1 ! sep>ation ( ! z9c is complete aft] /&+ f\r h\rs4 ,! ionic *anges connect$ ) ! precipitation ( ! z9c z z9c ammonium phosphate are simil> to ^? describ$ = magnesium ammonium phosphate1 except t ! z9c precipitate is soluble 9 an excess ( ammonium hydroxide1 probably z a result ( ! =mation ( complex ions ( ! g5]al "* ,zn7,,nh#c7d4 ,note #d3 ,! precipitate is wa%$ fir/ ) a dilute solution ( ! phosphate to prev5t a slight decomposition ( ! precipitate 7z a result ( hydrolysis7 if hot wat] alone is us$4 ,! alcohol is add$ to ! f9al wa%-wat] to promote ! subsequ5t dry+4 ,note #e3 ,! precipitate may be ignit$ & weigh$ z ,zn#b,p#b,o#g1 by cauti\sly heat+ ! porcela9 ,goo* crucible )9 a nickel or iron crucible1 us$ z a radiator4 ,! heat+ mu/ be v sl[ at fir/1 z ! escap+ ammonia may r$uce ! precipitate if x is heat$ too quickly4 ,note #f3 ,if ! ammonium sulphide produc$ a di/9ct precipitate1 ?is %\ld be collect$ on a small filt]1 dissolv$ 9 a few cubic c5timet]s ( dilute nitric acid1 & ! z9c reprecipitat$ z phosphate1 filt]$ (f1 dri$1 & weigh$1 & ! weight add$ to t ( ! ma9 precipitate4 ,note #g3 ,x has be5 f\nd t "s samples ( asbe/os are act$ ^u by ! phosphate solution & lose weight4 ,an error f ?is s\rce may be avoid$ by det]m9+ ! weight ( ! crucible & filt] aft] weigh+ ! precipitate4 ,= ?is purpose ! precipitate may be dissolv$ 9 dilute nitric acid1 ! asbe/os wa%$ ?or\ghly1 & ! crucible reweigh$4 ,note #h4 ,! details ( ?is me?od ( precipitation ( z9c are fully discuss$ 9 an article by ,dak91 6,zts*r4 ,anal4 ,*em461 #ci 7#aijj71 #bgc4 ,,det]m9ation ,,( ,,silica ,,9 ,,silicates ,( ! natural silicates1 or artificial silicates su* z slags & "s ( ! cem5ts1 a comp>atively few c be completely decompos$ by treatm5t ) acids1 b by f> ! l>g] numb] require fusion ) an alkal9e flux to effect decomposition & solution = analysis4 ,! proc$ure giv5 bel[ applies to silicates undecomposable by acids1 ( :i* ! m9]al feldsp> is tak5 z a typical example4 ,modifications ( ! proc$ure1 :i* are applicable to silicates :i* are completely or p>tially decomposable by acids1 are giv5 9 ! ,notes on page #aee4 ,,prep>ation ,,( ,,! ,,sample ,gr9d ab\t #c grams ( ! m9]al 9 an agate mort> 7,note #a7 until no gritt9ess is to be detect$1 or1 bett]1 until x w entirely pass ?r\gh a sieve made ( f9e silk bolt+ clo?4 ,! sieve may be made by plac+ a piece ( ! bolt+ clo? ov] ! top ( a small beak] 9 :i* ! gr\nd m9]al is plac$1 hold+ ! clo? 9 place by means ( a rubb] b& bel[ ! lip ( ! beak]4 ,by inv]t+ ! beak] ov] clean pap] & g5tly tapp+ x1 ! f9e p>ticles pass ?r\gh ! sieve1 leav+ ! co>s] p>ticles )9 ! beak]4 ,^! mu/ be return$ to ! mort> & gr\nd1 & ! process ( sift+ & gr9d+ repeat$ until ! entire sample passes ?r\gh ! sieve4 ,note #a3 ,if ! sample ( feldsp> = analysis is 9 ! massive or cry/all9e =m1 x %\ld be cru%$ 9 an iron mort> until ! pieces are ab\t half ! size ( a pea1 & !n transf]r$ to a /eel mort>1 9 :i* !y are r$uc$ to a co>se p[d]4 ,a wood5 mallet %\ld always be us$ to /rike ! pe/le ( ! /eel mort>1 & ! bl[s %\ld n be %>p4 ,x is pla9 t f9al gr9d+ 9 an agate mort> mu/ be cont9u$ until ! :ole ( ! portion ( ! m9]al orig9ally tak5 has be5 gr\nd s t x w pass ! bolt+ clo?1 o!rwise ! sift$ portion does n repres5t an av]age sample1 ! s(t] +r$i5ts1 if =eign matt] is pres5t1 be+ fir/ r$uc$ to p[d]4 ,= ?is reason x is be/ to />t ) n m ?an ! quantity ( ! feldsp> ne$$ = analysis4 ,! m9]al mu/ be ?or\ghly mix$ aft] ! gr9d+4 ,,fusion ,,& ,,solution ,,proc$ure4--,weigh into plat9um crucibles two portions ( ! gr\nd feldsp> ( ab\t #j4h gram ea*4 ,weigh on r\gh balances two portions ( anhydr\s sodium c>bonate1 ea* am\nt+ to ab\t six times ! weight ( ! feldsp> tak5 = analysis 7,note #a74 ,p\r ab\t ?ree f\r?s ( ! sodium c>bonate into ! crucible1 place ! latt] on a piece ( clean1 glaz$ pap]1 & ?or\ghly mix ! sub/ance & ! flux by c>efully /irr+ = sev]al m9utes ) a dry glass rod1 ! end ( :i* has be5 rec5tly heat$ & r\nd$ 9 a flame & sl[ly cool$4 ,! rod may be wip$ (f ) a small fragm5t ( filt] pap]1 :i* may be plac$ 9 ! crucible4 ,place ! rema9+ f\r? ( ! c>bonate on ! top ( ! mixture4 ,cov] ! crucible1 heat x to dull r$ness = five m9utes1 & !n gradually increase ! heat to ! full capacity ( a ,buns5 or ,tirrill burn] = tw5ty m9utes1 or until a quiet1 liquid fusion is obta9$ 7,note #b74 ,f9ally1 heat ! sides & cov] /rongly until any mat]ial :i* may h collect$ ^u !m is also br\ght to fusion4 ,all[ ! crucible to cool1 & remove ! fus$ mass z direct$ on page #aaf4 ,dis9tegrate ! mass by plac+ x 9 a previ\sly prep>$ mixture ( #ajj cc4 ( wat] & #ej cc4 ( dilute hydro*loric acid 7sp4 gr4 #a4ab7 9 a cov]$ cass]ole 7,note #c74 ,clean ! crucible & lid by means ( a little hydro*loric acid1 add+ ?is acid to ! ma9 solution 7,notes #d & #e74 ,note #a3 ,qu>tz1 & m9]als conta9+ v high p]c5tages ( silica1 may require eight or t5 p>ts by weight ( ! flux to insure a satisfactory decomposition4 ,note #b3 ,dur+ ! fusion ! feldsp>1 :i*1 :5 pure1 is a silicate ( alum9ium & ei!r sodium or potassium1 b usually conta9s "s iron1 calcium1 & magnesium1 is decompos$ by ! alkal9e flux4 ,! sodium ( ! latt] comb9es ) ! silicic acid ( ! silicate1 ) ! evolution ( c>bon dioxide1 :ile ab\t two ?irds ( ! alum9ium =ms sodium alum9ate & ! rema9d] is conv]t$ into basic c>bonate1 or ! oxide4 ,! calcium & magnesium1 if pres5t1 are *ang$ to c>bonates or oxides4 ,! heat is appli$ g5tly to prev5t a too viol5t reaction :5 fusion fir/ takes place4 ,note #c3 ,! solution ( a silicate by a /rong acid is ! result ( ! comb9ation ( ! ,h ions ( ! acid & ! silicate ions ( ! silicate to =m a slightly ioniz$ silicic acid4 ,z a consequ5ce1 ! conc5tration ( ! silicate ions 9 ! solution is r$uc$ ne>ly to z]o1 & m silicate dissolves to re-e/abli% ! di/urb$ equilibrium4 ,?is process repeats itself until all ( ! silicate is br\ght into solution4 ,:e!r ! result+ solution ( ! silicate conta9s or?o-silicic acid 7,h#d,si,o#d7 or :e!r x is a colloidal solution ( "s o!r less hydrat$ acid1 su* z meta-silicic acid 7,h#b,si,o#c71 is a matt] t is /ill debatable4 ,x is c]ta91 h[ev]1 t ! gelat9\s mat]ial :i* readily sep>ates f su* solutions is ( ! nature ( a hydrogel1 t is1 a colloid :i* is insoluble 9 wat]4 ,?is sub/ance :5 heat$ to #ajj;,c41 or high]1 is completely dehydrat$1 leav+ only ! anhydride1 ,si,o#b4 ,! *anges may be repres5t$ by ! equation3 ,si,o#c-- #b;,h -- ,h#b,si,o#c -- ,h#b,o ,si,o#b4 ,note #d3 ,a portion ( ! fus$ mass is usually project$ upw>d by ! escap+ c>bon dioxide dur+ ! fusion4 ,! crucible mu/ !re=e be kept cov]$ z mu* z possible & ! lid c>efully clean$4 ,note #e3 ,a gritty residue rema9+ aft] ! dis9tegration ( ! fus$ mass by acid indicates t ! sub/ance has be5 b imp]fectly decompos$4 ,su* a residue %\ld be filt]$1 wa%$1 dri$1 ignit$1 & aga9 fus$ ) ! alkal9e flux2 or1 if ! quantity ( mat]ial at h& w p]mit1 x is bett] to reject ! analysis1 & to use increas$ c>e 9 gr9d+ ! m9]al & 9 mix+ x ) ! flux4 ,,dehydration ,,& ,,filtration ,,proc$ure4--,evaporate ! solution ( ! fusion to dryness1 /irr+ frequ5tly until ! residue is a dry p[d]4 ,moi/5 ! residue ) #e cc4 ( /rong hydro*loric acid 7sp4 gr4 #a4bj7 & evaporate aga9 to dryness4 ,heat ! residue = at lea/ "o h\r at a temp]ature ( #aaj;,c4 7,note #a74 ,aga9 moi/5 ! residue ) conc5trat$ hydro*loric acid1 w>m g5tly1 mak+ sure t ! acid comes into contact ) ! :ole ( ! residue1 dilute to ab\t #bjj cc4 & br+ to boil+4 ,filt] (f ! silica )\t mu* delay 7,note #b71 & wa% five times ) w>m dilute hydro*loric acid 7"o "p dilute acid 7#a4ab sp4 gr47 to ?ree p>ts ( wat]74 ,all[ ! filt] to dra9 = a few mom5ts1 !n place a clean beak] bel[ ! funnel & wa% ) wat] until free f *lorides1 disc>d+ ^! wa%+s4 ,evaporate ! orig9al filtrate to dryness1 dehydrate at #aaj;,c4 = "o h\r 7,note #c71 & proce$ z be=e1 us+ a second filt] to collect ! silica aft] ! second dehydration4 ,wa% ?is filt] ) w>m1 dilute hydro*loric acid 7,note #d71 & f9ally ) hot wat] until free f *lorides4 ,note #a3 ,! silicic acid mu/ be fre$ f its comb9ation ) a base 7sodium1 9 ?is in/ance7 be=e x c be dehydrat$4 ,! excess ( hydro*loric acid accompli%es ?is lib]ation4 ,by dis9tegrat+ ! fus$ mass ) a consid]able volume ( dilute acid ! silicic acid is at fir/ held 9 solution to a l>ge ext5t4 ,imm$iate treatm5t ( ! fus$ mass ) /rong acid is likely to cause a semi-gelat9\s silicic acid to sep>ate at once & to inclose alkali salts or alum9a4 ,a floccul5t residue w (t5 rema9 aft] ! decomposition ( ! fus$ mass is effect$4 ,?is is usually p>tially dehydrat$ silicic acid & does n require fur!r treatm5t at ?is po9t4 ,! progress ( ! dehydration is indicat$ by ! behavior ( ! solution1 :i* z evaporation proce$s usually gelat9izes4 ,on ?is acc\nt x is necess>y to all[ ! solution to evaporate on a /eam ba?1 or to /ir x vigor\sly1 to avoid loss by spatt]+4 ,note #b3 ,to obta9 an approximately pure silica1 ! residue aft] evaporation mu/ be ?or\ghly extract$ by w>m+ ) hydro*loric acid1 & ! solution freely dilut$ to prev5t1 z f> z possible1 ! inclosure ( ! residual salts 9 ! p>ticles ( silica4 ,! filtration %\ld take place )\t delay1 z ! dehydrat$ silica sl[ly dissolves 9 hydro*loric acid on /&+4 ,note #c3 ,x has be5 %[n by ,hillebr& t silicic acid _c be completely dehydrat$ by a s+le evaporation & heat+1 nor by sev]al su* treatm5ts1 unless an int]m$iate filtration ( ! silica occurs4 ,if1 h[ev]1 ! silica is remov$ & ! filtrates are aga9 evaporat$ & ! residue heat$1 ! am\nt ( silica rema9+ 9 solution is usually negligible1 al?\gh sev]al evaporations & filtrations are requir$ ) "s silicates to insure absolute accuracy4 ,x is probable t temp]atures above #ajj;,c4 are n absolutely necess>y to dehydrate ! silica2 b x is recomm5d$1 z t5d+ to leave ! silica 9 a bett] condition = filtration ?an :5 ! l[] temp]ature ( ! wat] ba? is us$4 ,?is1 & _m o!r po9ts 9 ! analysis ( silicates1 are fully discuss$ by ,dr4 ,hillebr& 9 ! admirable monograph on ,! ,analysis ( ,silicate & ,c>bonate ,rocks1 ,bullet9 ,no4 #gjj ( ! ,unit$ ,/ates ,geological ,survey4 ,! d\ble evaporation & filtration spok5 ( above are ess5tial because ( ! relatively l>ge am\nt ( alkali salts 7sodium *loride7 pres5t aft] evaporation4 ,= ! highe/ accuracy 9 ! det]m9ation ( silica1 or ( iron & alum9a1 x is also necess>y to exam9e = silica ! precipitate produc$ 9 ! filtrate by ammonium hydroxide by fus+ x ) acid potassium sulphate & solution ( ! fus$ mass 9 wat]4 ,! insoluble silica is filt]$1 wa%$1 & weigh$1 & ! weight add$ to ! weight ( silica previ\sly obta9$4 ,note #d3 ,alum9ium & iron are likely to be ?r[n d[n z basic salts f hot1 v dilute solutions ( _! *lorides1 z a result ( hydrolysis4 ,if ! silica 7 wa%$ only ) hot wat]1 ! solution ( ^! *lorides rema9+ 9 ! filt] aft] ! passage ( ! orig9al filtrate w\ld gradually become s dilute z to ?r[ d[n basic salts )9 ! pores ( ! filt]1 :i* w\ld rema9 ) ! silica4 ,to avoid ?is1 an acid wa%-wat] is us$ until ! alum9ium & iron are practically remov$4 ,! acid is !n remov$ by wat]4 ,,ignition ,,& ,,te/+ ,,( ,,silica ,,proc$ure4--,transf] ! two wa%$ filt]s belong+ to ea* det]m9ation to a plat9um crucible1 :i* ne$ n be previ\sly weigh$1 & burn (f ! filt] 7,note #a74 ,ignite = ?irty m9utes ov] ! bla/ lamp ) ! cov] on ! crucible1 & !n = p]iods ( t5 m9utes1 until ! weight is con/ant4 ,:5 a con/ant weight has be5 obta9$1 p\r into ! crucible ab\t #c cc4 ( wat]1 & !n #c cc4 ( hydr(luoric acid4 6,?is mu/ be done 9 a hood ) a good draft & great c>e mu/ be tak5 n to come into contact ) ! acid or to inhale its fumes 7,note #b674 ,if ! precipitate has dissolv$ 9 ?is quantity ( acid1 add two drops ( conc5trat$ sulphuric acid1 & heat v sl[ly 7always "u ! hood7 until all ! liquid has evaporat$1 f9ally ignit+ to r$ness4 ,cool 9 a desiccator1 & weigh ! crucible & residue4 ,d$uct ?is weight f ! previ\s weight ( crucible & impure silica1 & f ! diff]5ce calculate ! p]c5tage ( silica 9 ! sample 7,note #c74 ,note #a3 ,! silica und]goes no *ange dur+ ! ignition beyond ! removal ( all traces ( wat]2 b ,hillebr& 76loc4 cit467 has %[n t ! silica holds moi/ure s t5aci\sly t prolong$ ignition ov] ! bla/ lamp is necess>y to remove x entirely4 ,?is f9ely divid$1 ignit$ silica t5ds to absorb moi/ure1 & %\ld be weigh$ quickly4 ,note #b3 ,not)/&+ all precautions1 ! ignit$ precipitate ( silica is r>ely :olly pure4 ,x is te/$ by volatilisation ( ! silica z silicon fluoride aft] solution 9 hydr(luoric acid1 &1 if ! analysis has be5 prop]ly conduct$1 ! residue1 aft] treatm5t ) ! acids & ignition1 %\ld n exce$ #a mg4 ,! acid produces ulc]ation if br\ght into contact ) ! sk91 & its fumes are excessively h>mful if inhal$4 ,note #c3 ,! impurities are probably weigh$ ) ! orig9al precipitate 9 ! =m ( oxides4 ,! addition ( ! sulphuric acid displaces ! hydr(luoric acid1 & x may be assum$ t ! result+ sulphates 7usually ( iron or alum9ium7 are conv]t$ to oxides by ! f9al ignition4 ,x is obvi\s t unless ! sulphuric & hydr(luoric acids us$ are kn[n to leave no residue on evaporation1 a quantity equal to t employ$ 9 ! analysis mu/ be evaporat$ & a correction appli$ = any residue f\nd4 ,note #d3 ,if ! silicate to be analyz$ is %[n by a previ\s qualitative exam9ation to be completely decomposable1 x may be directly treat$ ) hydro*loric acid1 ! solution evaporat$ to dryness1 & ! silica dehydrat$ & fur!r treat$ z describ$ 9 ! case ( ! feldsp> aft] fusion4 ,a silicate :i* gelat9izes on treatm5t ) acids %\ld be mix$ fir/ ) a little wat]1 & ! /rong acid add$ 9 small portions ) /irr+1 o!rwise ! gelat9\s silicic acid incloses p>ticles ( ! orig9al silicate & prev5ts decomposition4 ,! wat]1 by sep>at+ ! p>ticles & slightly less5+ ! rapidity ( action1 prev5ts ?is difficulty4 ,?is proc$ure is "o :i* applies 9 g5]al to ! solution ( f9e m9]al p[d]s 9 acids4 ,if a small residue rema9s undecompos$ by ! treatm5t ( ! silicate ) acid1 ?is may be filt]$1 wa%$1 ignit$ & fus$ ) sodium c>bonate & a solution ( ! fus$ mass add$ to ! orig9al acid solution4 ,?is d\ble proc$ure has an advantage1 9 t x avoids add+ s l>ge a quantity ( sodium salts z is requir$ = dis9tegration ( ! :ole ( ! silicate by ! fusion me?od4 ,,"p ,,iv ,,/oi*iometry ,! problems ) :i* ! analytical *emi/ has to deal are n1 z a matt] ( actual fact1 difficult ei!r to solve or to und]/&4 ,t !y appe> difficult to _m /ud5ts is due to ! fact t1 in/ead ( und]/&+ ! pr9ciples :i* und]lie ea* ( ! small numb] ( types into :i* ^! problems may be gr\p$1 ea* problem is approa*$ z an individual puzzle1 unrelat$ to o!rs already solv$ or expla9$4 ,?is attitude ( m9d %\ld be c>efully avoid$4 ,x is obvi\s t ability to make ! calculations necess>y = ! int]pretation ( analytical data is no less important ?an ! manipulative skill requir$ to obta9 !m1 & t a mod]ate "t sp5t 9 ! c>eful /udy ( ! solutions ( ! typical problems :i* foll[ may save mu* lat] emb>rassm5t4 #a4 ,x is (t5 necess>y to calculate :at is kn[n z a *emical factor1 or its equival5t log>i?mic value call$ a log factor1 = ! conv]sion ( ! weight ( a giv5 *emical sub/ance into an equival5t weight ( ano!r sub/ance4 ,?is is1 9 reality1 a v simple problem 9 proportion1 mak+ use ( ! atomic or molecul> weights ( ! sub/ances 9 "q :i* are *emically equival5t to ea* o!r4 ,"o ( ! simple/ cases ( ?is sort is ! foll[+3 ,:at is ! factor = ! conv]sion ( a giv5 weight ( b>ium sulphate 7,ba,s,o#d7 into an equival5t weight ( sulphur 7,s78 ,! molecul> weight ( ,ba,s,o#d is #bcc4e4 ,!re is "o atom ( ,s 9 ! molecule & ! atomic weight ( ,s is #cb4a4 ,! *emical factor is1 !re=e1 #cb4a_/bcc4e1 or #j4acge & ! weight ( ,s correspond+ to a giv5 weight ( ,ba,s,o#d is f\nd by multiply+ ! weight ( ,ba,s,o#d by ?is factor4 ,if ! problem takes ! =m1 ,:at is ! factor = ! conv]sion ( a giv5 weight ( f]ric oxide 7,fe#b,o#c7 into f]r\s oxide 7,fe,o71 or ( a giv5 weight ( mangano-manganic oxide 7,mn#c,o#d7 into manganese 7,mn78 ! pr9ciple involv$ is ! same1 b x mu/ !n be not$ t1 9 ! fir/ in/ance1 ea* molecule ( ,fe#b,o#c w be equival5t to two molecules ( ,fe,o1 & 9 ! second in/ance t ea* molecule ( ,mn#c,o#d is equival5t to ?ree atoms ( ,mn4 ,! respective factors !n become 7#b;,fe,o_/,fe#b,o#c7 or 7#adc4f_/aei4f7 & 7#c,mn_/,mn#c,o#d7 or 7#afd4g_/bbh4g74 ,x is obvi\s t ! ari?metical processes involv$ 9 ?is type ( problem are extremely simple4 ,x is only necess>y to obs]ve c>efully ! *emical equival5ts4 ,x is pla9ly incorrect to express ! ratio ( f]r\s to f]ric oxide z 7,fe,o_/,fe#b,o#c71 s9ce ea* molecule ( ! f]ric oxide w yield two molecules ( ! f]r\s oxide4 ,mi/akes ( ?is sort are easily made & con/itute "o ( ! mo/ frequ5t s\rces ( error4 #b4 ,a type ( problem :i* is slightly m complicat$ 9 appe>ance1 b exactly comp>able 9 pr9ciple1 is ! foll[+3 ,:at is ! factor = ! conv]sion ( a giv5 weight ( f]r\s sulphate 7,fe,s,o#d71 us$ z a r$uc+ ag5t aga9/ potassium p]manganate1 into ! equival5t weight ( sodium oxalate 7,na#b;,c#b,o#d78 ,to det]m9e ! *emical equival5ts 9 su* an in/ance x is necess>y to inspect ! *emical reactions involv$4 ,^! are3 #aj;,fe,s,o#d #b,k,mn,o#d #h;,h#b,,s#d -- #e;,fe#b7,,s#d7c ,k#b,,s#d #b,mn,s,o#d #h;,h#b,o1 #e,na#b;,c#b,o#d #b,k,mn,o#d #h;,h#b,,s#d -- #e,na#b,,s#d #aj;,,co#b ,k#b,,s#d #b,mn,s,o#d #h;,h#b,o4 ,x is evid5t t #aj;,fe,s,o#d 9 ! "o case1 & #e,na#b;,c#b,o#d 9 ! o!r1 ea* react ) #b,k,mn,o#d4 ,^! molecul> quantities are !re=e equival5t1 & ! factor becomes 7#aj;,fe,s,o#d_/e,na#b;,c#b,o#d7 or 7#b;,fe,s,o#d_/,na#b;,c#b,o#d7 or 7#cjc4h_/acd74 ,aga91 let x be assum$ t x is desir$ to det]m9e ! factor requir$ = ! conv]sion ( a giv5 weight ( potassium p]manganate 7,k,mn,o#d7 into an equival5t weight ( potassium bi*romate 7,k#b;,cr#b,o#g71 ea* act+ z an oxidiz+ ag5t aga9/ f]r\s sulphate4 ,! reactions involv$ are3 #aj;,fe,s,o#d #b,k,mn,o#d #h;,h#b,,s#d -- #e;,fe#b7,,s#d7c ,k#b,,s#d #b,mn,s,o#d #h;,h#b,o1 #f;,fe,s,o#d ,k#b;,cr#b,o#g #g;,h#b,,s#d -- #c;,fe#b7,,s#c7c ,k#b,,s#d ,cr#b7,,s#d7c #g;,h#b,o4 ,an inspection ( ^! equations %[s t #b,,kmo#d react ) #aj;,fe,s,o#d1 :ile ,k#b;,cr#b,o#g reacts ) #f;,fe,s,o#d4 ,^! are n equival5t1 b if ! fir/ equation is multipli$ by #c & ! second by #e ! numb] ( molecules ( ,fe,s,o#d is !n ! same 9 bo?1 & ! numb] ( molecules ( ,k,mn,o#d & ,k#b;,cr#b,o#g react+ ) ^! #cj molecules become #f & #e respectively4 ,^! are obvi\sly *emically equival5t & ! desir$ factor is express$ by ! fraction 7#f,k,mn,o#d_/e,k#b;,cr#b,o#g7 or 7#idh4j_/adga4j74 #c4 ,x is sometimes necess>y to calculate ! value ( solutions accord+ to ! pr9ciples j expla9$1 :5 sev]al successive reactions are involv$4 ,su* problems may be solv$ by a s]ies ( proportions1 b x is usually possible to elim9ate ! common factors & solve b a s+le "o4 ,= example1 ! am\nt ( ,mn,o#b 9 a sample ( ! m9]al pyrolusite may be det]m9$ by dissolv+ ! m9]al 9 hydro*loric acid1 absorb+ ! evolv$ *lor9e 9 a solution ( potassium iodide1 & measur+ ! lib]at$ iod9e by titration ) a /&>d solution ( sodium ?iosulphate4 ,! reactions involv$ are3 ,mn,o#b #d;,h,cl -- ,mn,cl#b #b;,h#b,o ,cl#b ,cl#b #b,,ki -- ,i#b #b,k,cl ,i#b #b,na#b,s#b,o#c -- #b,na,i ,na#b,s#d,o#f ,assum+ t ! weight ( ?iosulphate correspond+ to ! volume ( sodium ?iosulphate solution us$ is kn[n1 :at is ! correspond+ weight ( manganese dioxide8 ,f ! reactions giv5 above1 ! foll[+ proportions may be /at$3 #b,na#b,s#b,o#c3;,i#b #caf4d3bec4i1 ,i#b3;,cl#b #bec4i3ga1 ,cl#b3,mn,o#b #ga3hf4i4 ,aft] cancel+ ! common factors1 !re rema9s #b,na#b,s#b,o#c3,mn,o#b #caf4d3hf4i1 & ! factor = ! conv]sion ( ?iosulphate into an equival5t ( manganese dioxide is #hf4i_/caf4d4 #d4 ,to calculate ! volume ( a reag5t requir$ = a specific op]ation1 x is necess>y to "k ! exact reaction :i* is to be br\ght ab\t1 &1 z ) ! calculation ( factors1 to keep 9 m9d ! molecul> relations betwe5 ! reag5t & ! sub/ance react$ ^u4 ,= example1 to e/imate ! weight ( b>ium *loride necess>y to precipitate ! sulphur f #j4a gram ( pure pyrite 7,fe,s#b71 ! proportion %\ld read #dhh4 #abj4j #b7;,ba,cl#b4b;,h#b,o73,fe,s#b x3#j4a1 :]e 6x6 repres5ts ! weight ( ! *loride requir$4 ,ea* ( ! two atoms ( sulphur w =m ^u oxidation a molecule ( sulphuric acid or a sulphate1 :i*1 9 turn1 w require a molecule ( ! b>ium *loride = precipitation4 ,to det]m9e ! quantity ( ! b>ium *loride requir$1 x is necess>y to include 9 its molecul> weight ! wat] ( cry/allization1 s9ce ?is is insep>able f ! *loride :5 x is weigh$4 ,?is applies equally to o!r simil> in/ances4 ,if ! /r5g? ( an acid is express$ 9 p]c5tage by weight1 due reg>d mu/ be paid to its specific gravity4 ,= example1 hydro*loric acid 7sp4 gr4 #a4ab7 conta9s #bc4h p] c5t ,h,cl 6by weight62 t is1 #j4bfff gram ,h,cl 9 ea* cubic c5timet]4 #e4 ,x is sometimes desirable to avoid ! manipulation requir$ = ! sep>ation ( ! con/itu5ts ( a mixture ( sub/ances by mak+ :at is call$ an indirect analysis4 ,= example1 9 ! analysis ( silicate rocks1 ! sodium & potassium pres5t may be obta9$ 9 ! =m ( _! *lorides & weigh$ toge!r4 ,if ! weight ( su* a mixture is kn[n1 & also ! p]c5tage ( *lor9e pres5t1 x is possible to calculate ! am\nt ( ea* *loride 9 ! mixture4 ,let x be assum$ t ! weight ( ! mix$ *lorides is #j4ae gram1 & t x conta9s #ec p] c5t ( *lor9e4 ,! simple/ solution ( su* a problem is rea*$ ?r\gh algebraic me?ods4 ,! weight ( *lor9e is evid5tly #j4ae x #j4ec1 or #j4jgie gram4 ,let x repres5t ! weight ( sodium *loride pres5t & y t ( potassium *loride4 ,! molecul> weight ( ,na,cl is #eh4e & t ( ,k,cl is #gd4f4 ,! atomic weight ( *lor9e is #ce4e4 ,!n x y #j4ae 7#ce4e_/eh4e7x 7#ce4e_/gd4f7y #j4jjgie ,solv+ ^! equations = x %[s ! weight ( ,na,cl to be #j4jfbe gram4 ,! weight ( ,k,cl is f\nd by subtract+ ?is f #j4ae4 ,! above is "o ( ! mo/ common types ( indirect analyses4 ,o!rs are m complex b !y c be r$uc$ to algebraic expressions & solv$ by _! aid4 ,x %\ld1 h[ev]1 be not$ t ! results obta9$ by ^! indirect me?ods _c be dep5d$ ^u = high accuracy1 s9ce slight errors 9 ! det]m9ation ( ! common con/itu5t1 z *lor9e 9 ! above mixture1 w cause consid]able v>iations 9 ! values f\nd = ! compon5ts4 ,!y %\ld n be employ$ :5 direct me?ods are applicable1 if accuracy is ess5tial4 ,,problems 7,! reactions necess>y = ! solution ( ^! problems are ei!r /at$ ) ! problem or may be f\nd 9 ! e>li] text4 ,9 ! calculations f :i* ! answ]s are d]iv$1 ! atomic weights giv5 on page #aie h be5 employ$1 us+1 h[ev]1 only ! fir/ decimal b increas+ ?is by #a :5 ! second decimal is #e or above4 ,?us1 #ci4a has be5 tak5 z ! atomic weight ( potassium1 #cb4a = sulphur1 etc4 ,?is has be5 done m]ely to secure uni=mity ( treatm5t1 & ! /ud5t %\ld rememb] t x is always well to take into acc\nt ! degree ( accuracy desir$ 9 a p>ticul> in/ance 9 det]m9+ ! numb] ( decimal places to reta94 ,f\r-place log>i?ms 7 employ$ 9 ! calculations4 ,:]e f\r figures are giv5 9 ! answ]1 ! la/ figure may v>y by "o or 7r>ely7 by two units1 accord+ to ! me?od by :i* ! problem is solv$47 ,,volumetric ,,analysis #a4 ,h[ _m grams ( pure potassium hydroxide are requir$ = exactly #a lit] ( normal alkali solution8 6,answ]63 #ef4a grams4 #b4 ,calculate ! equival5t 9 grams 7a7 ( sulphuric acid z an acid2 7b7 ( hydro*loric acid z an acid2 7c7 ( oxalic acid z an acid2 7d7 ( nitric acid z an acid4 6,answ]s63 7a7 #di4je2 7b7 #cf4e2 7c7 #fc2 7d7 #fc4 #c4 ,calculate ! equival5t 9 grams ( 7a7 potassium hydroxide2 7b7 ( sodium c>bonate2 7c7 ( b>ium hydroxide2 7d7 ( sodium bic>bonate :5 titrat$ ) an acid4 6,answ]s63 7a7 #ef4a2 7b7 #ec4h2 7c7 #he4g2 7d7 #hd4 #d4 ,:at is ! equival5t 9 grams ( ,na#b;,,hpo#d 7a7 z a phosphate2 7b7 z a sodium salt8 6,answ]s63 7a7 #dg4cc2 7b7 #ga4j4 #e4 ,a sample ( aque\s hydro*loric acid has a specific gravity ( #a4ab & conta9s #bc4ha p] c5t hydro*loric acid by weight4 ,calculate ! grams & ! milliequival5ts ( hydro*loric acid 7,h,cl7 9 ea* cubic c5timet] ( ! aque\s acid4 6,answ]s63 #j4bffg gram2 #g4cjg milliequival5ts4 #f4 ,h[ _m cubic c5timet]s ( hydro*loric acid 7sp4 gr4 #a4bj conta9+ #ci4hj p] c5t ,h,cl by weight7 are requir$ to furni% #cf4de grams ( ! gase\s comp\nd8 6,answ]63 #gf4cc cc4 #g4 ,a giv5 solution conta9s #j4ajfc equival5ts ( hydro*loric acid 9 #igf cc4 ,:at is its normal value8 6,answ]63 #j4ajhi ,n4 #h4 ,9 /&>diz+ a hydro*loric acid solution x is f\nd t #dg4bf cc4 ( hydro*loric acid are exactly equival5t to #a4baf grams ( pure sodium c>bonate1 us+ me?yl orange z an indicator4 ,:at is ! normal value ( ! hydro*loric acid8 6,answ]63 #j4dhee ,n4 #i4 ,conv]t #db4ge cc4 ( #j4eafb normal hydro*loric acid to ! equival5t volume ( normal hydro*loric acid4 6,answ]63 #bb4jg cc4 #aj4 ,a solution conta9+ #be4bg cc4 ( #j4ajfe normal hydro*loric acid is add$ to "o conta9+ #ib4ba cc4 ( #j4edca normal sulphuric acid & #ej cc4 ( exactly normal potassium hydroxide add$ f a pipette4 ,is ! solution acid or alkal9e8 ,h[ _m cubic c5timet]s ( #j4a normal acid or alkali mu/ be add$ to exactly neutralize ! solution8 6,answ]63 #bg4f cc4 alkali 7solution is acid74 #aa4 ,by exp]im5t ! normal value ( a sulphuric acid solution is f\nd to be #j4eagb4 ,( ?is acid #ci4fe cc4 are exactly equival5t to #ba4gd cc4 ( a /&>d alkali solution4 ,:at is ! normal value ( ! alkali8 6,answ]63 #j4idcb ,n4 #ab4 ,a solution ( sulphuric acid is /&>diz$ aga9/ a sample ( calcium c>bonate :i* has be5 previ\sly accurately analyz$ & f\nd to conta9 #ib4dd ,ca,c,o#c & no o!r basic mat]ial4 ,! sample weigh+ #j4gdbc gram 0 titrat$ by add+ an excess ( acid 7#db4db cc47 & titrat+ ! excess ) sodium hydroxide solution 7#aa4bb cc474 #a cc4 ( acid is equival5t to #j4iigf cc4 ( sodium hydroxide4 ,calculate ! normal value ( ea*4 6,answ]s63 ,acid #j4dcih ,n2 alkali #j4ddji ,n4 #ac4 ,giv5 five #aj cc4 portions ( #j4a normal hydro*loric acid1 7a7 h[ _m grams ( silv] *loride w be precipitat$ by a portion :5 an excess ( silv] nitrate is add$8 7b7 h[ _m grams ( pure anhydr\s sodium c>bonate 7,na#b;,,co#c7 w be neutraliz$ by a portion ( x8 7c7 h[ _m grams ( silv] w !re be 9 ! silv] *loride =m$ :5 an excess ( silv] nitrate is add$ to a portion8 7d7 h[ _m grams ( iron w be dissolv$ to ,fe,cl#b by a portion ( x8 7e7 h[ _m grams ( magnesium *loride w be =m$ & h[ _m grams ( c>bon dioxide lib]at$ :5 an excess ( magnesium c>bonate is treat$ ) a portion ( ! acid8 6,answ]s63 7a7 #j4adcd2 7b7 #j4jec2 7c7 #j4ajgi2 7d7 #j4jbgi2 7e7 #j4jdgfe1 & #j4jbb4 #ad4 ,if #cj4jj grams ( potassium tetroxalate 7,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o7 are dissolv$ & ! solution dilut$ to exactly #a lit]1 & #dj cc4 are neutraliz$ ) #bj cc4 ( a potassium c>bonate solution1 :at is ! normal value ( ! c>bonate solution8 6,answ]63 #j4gjhd ,n4 #ae4 ,h[ _m cubic c5timet]s ( #j4c normal sulphuric acid w be requir$ to neutralize 7a7 #cj cc4 ( #j4e normal potassium hydroxide2 7b7 to neutralize #cj cc4 ( #j4e normal b>ium hydroxide2 7c7 to neutralize #bj cc4 ( a solution conta9+ #aj4jb grams ( potassium bic>bonate p] #ajj cc42 7d7 to give a precipitate ( b>ium sulphate weigh+ #j4dcbj gram8 6,answ]s63 7a7 #ej cc42 7b7 #ej cc42 7c7 #ff4gc cc42 7d7 #ab4cc cc4 #af4 ,x is desir$ to dilute a solution ( sulphuric acid ( :i* #a cc4 is equival5t to #j4ajbg gram ( pure sodium c>bonate to make x exactly #a4bej normal4 #gjj cc4 ( ! solution are available4 ,to :at volume mu/ x be dilut$8 6,answ]63 #ajhd cc4 #ag4 ,giv5 ! foll[+ data3 #a cc4 ( ,na,o,h #a4aag cc4 ,h,cl4 ,! ,h,cl is #j4dhgf ,n4 ,h[ mu* wat] mu/ be add$ to #ajj cc4 ( ! alkali to make x exactly #j4e ,n48 6,answ]63 #i4j cc4 #ah4 ,:at is ! normal value ( a sulphuric acid solution :i* has a specific gravity ( #a4hci & conta9s #ie ,h#b,,s#d by weight8 6,answ]63 #ce4fa ,n4 #ai4 ,a sample ( ,ro*elle ,salt 7,k,na,c#d;,h#d,o#f4d;,h#b,o71 aft] ignition 9 plat9um to conv]t x to ! d\ble c>bonate1 is titrat$ ) sulphuric acid1 us+ me?yl orange z an indicator4 ,f ! foll[+ data calculate ! p]c5tage purity ( ! sample3 ,wt4 sample #j4iejj gram ,h#b,,s#d us$ #dc4fe cc4 ,na,o,h us$ #a4gb cc4 #a cc4 ,h#b,,s#d #a4jfd cc4 ,na,o,h ,normal value ,na,o,h #j4acba ,n4 6,answ]63 #hg4gb cc4 #bj4 ,"o gram ( a mixture ( #ej sodium c>bonate & #ej potassium c>bonate is dissolv$ 9 wat]1 & #ag4cf cc4 ( #a4jge ,n acid is add$4 ,is ! result+ solution acid or alkal9e8 ,h[ _m cubic c5timet]s ( #a4jge ,n acid or alkali w h to be add$ to make ! solution exactly neutral8 6,answ]s63 ,acid2 #a4hf cc4 alkali4 #ba4 ,9 prep>+ an alkal9e solution = use 9 volumetric "w1 an analy/1 because ( %ortage ( *emicals1 mix$ exactly #df4cb grams ( pure ,,koh & #bg4fd grams ( pure ,na,o,h1 & aft] dissolv+ 9 wat]1 dilut$ ! solution to exactly "o lit]4 ,h[ _m cubic c5timet]s ( #a4jbb ,n hydro*loric acid are necess>y to neutralize #ej cc4 ( ! basic solution8 6,answ]63 #gd4ah cc4 #bb4 ,"o gram ( crude ammonium salt is treat$ ) /rong potassium hydroxide solution4 ,! ammonia lib]at$ is di/ill$ & collect$ 9 #ej cc4 ( #j4e ,n acid & ! excess titrat$ ) #a4ee cc4 ( #j4e ,n sodium hydroxide4 ,calculate ! p]c5tage ( ,,nh#c 9 ! sample4 6,answ]63 #da4ag4 #bc4 ,9 titrat+ solutions ( alkali c>bonates 9 ! pres5ce ( ph5olph?ale91 ! color *ange takes place :5 ! c>bonate has be5 conv]t$ to bic>bonate4 ,9 ! pres5ce ( me?yl orange1 ! color *ange takes place only :5 ! c>bonate has be5 completely neutraliz$4 ,f ! foll[+ data1 calculate ! p]c5tages ( ,na#b;,,co#c & ,na,o,h 9 an impure mixture4 ,weight ( sample1 #a4ejj grams2 ,h,cl 7#j4e ,n7 requir$ = ph5olph?ale9 end-po9t1 #bh4he cc42 ,h,cl 7#j4e ,n7 requir$ to complete ! titration aft] add+ me?yl orange1 #bc4he cc4 6,answ]s63 #f4fg ,na,o,h2 #hd4bh ,na#b;,,co#c4 #bd4 ,a sample ( sodium c>bonate conta9+ sodium hydroxide weighs #a4agi grams4 ,x is titrat$ ) #j4cj ,n hydro*loric acid1 us+ ph5olph?ale9 9 cold solution z an indicator & becomes colorless aft] ! addition ( #dh4af cc4 ,me?yl orange is add$ & #bd4jh cc4 are ne$$ = complete neutralization4 ,:at is ! p]c5tage ( ,na,o,h & ,na#b;,,co#c8 6,answ]s63 #bd4ej ,na,o,h2 #fd4ib ,na#b;,,co#c4 #be4 ,f ! foll[+ data1 calculate ! p]c5tages ( ,na#b;,,co#c & ,na,h,c,o#c 9 an impure mixture4 ,weight ( sample #a4jjj gram2 volume ( #j4be ,n hydro*loric acid requir$ = ph5olph?ale9 end-po9t1 #bf4dj cc42 aft] add+ an excess ( acid & boil+ out ! c>bon dioxide1 ! total volume ( #j4be ,n hydro*loric acid requir$ = ph5olph?ale9 end-po9t1 #fg4aj cc4 6,answ]63 #fi4ie ,na#b;,,co#c2 #cj4jb ,na,h,c,o#c4 #bf4 ,9 ! analysis ( a "o-gram sample ( soda a%1 :at mu/ be ! normality ( ! acid 9 ord] t ! numb] ( cubic c5timet]s ( acid us$ %all repres5t ! p]c5tage ( c>bon dioxide pres5t8 6,answ]63 #j4dedd gram4 #bg4 ,:at weight ( pe>l a% mu/ be tak5 = analysis 9 ord] t ! numb] ( cubic c5timet]s ( #j4e ,n acid us$ may be equal to "o ?ird ! p]c5tage ( ,k#b;,,co#c8 6,answ]63 #a4aeb grams4 #bh4 ,:at weight ( cream ( t>t> mu/ h be5 tak5 = analysis 9 ord] to h obta9$ #ig4fj ,,khc#d;,h#d,o#f 9 an analysis involv+ ! foll[+ data3 ,na,o,h us$ #cj4jf cc42 ,h#b,,s#d solution us$ #j4ej cc42 #a cc4 ,h#b,,s#d sol4 #j4jbee gram ,ca,c,o#c2 #a cc4 ,h#b,,s#d sol4 #a4jb cc4 ,na,o,h sol48 6,answ]63 #b4hdf grams4 #bi4 ,calculate ! p]c5tage ( potassium oxide 9 an impure sample ( potassium c>bonate f ! foll[+ data3 ,weight ( sample #a4jj gram2 ,h,cl sol4 us$ #ee4ij cc42 ,na,o,h sol4 us$ #j4db cc42 #a cc4 ,na,o,h sol4 #j4jjhdgc gram ( ,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o2 #b cc4 ,h,cl sol4 #e cc4 ,na,o,h sol4 6,answ]63 #fe4fh4 #cj4 ,calculate ! p]c5tage purity ( a sample ( calcite 7,ca,c,o#c7 f ! foll[+ data3 7,/&>dization72 ,weight ( ,h#b;,c#b,o#d4b;,h#b,o #j4bdfj gram2 ,na,o,h solution us$ #da4jc cc42 ,h,cl solution us$ #j4fc2 #a cc4 ,na,o,h solution #a4aij cc4 ,h,cl solution4 7,analysis72 ,weight ( sample #j4abjj gram2 ,h,cl us$ #cf4ch cc42 ,na,o,h us$ #f4bj cc4 6,answ]63 #ig4ig4 #ca4 ,x is desir$ to dilute a solution ( hydro*loric acid to exactly #j4je ,n4 ,! foll[+ data are giv53 #dd4ig cc4 ( ! hydro*loric acid are equival5t to #dc4gf cc4 ( ! ,na,o,h solution4 ,! ,na,o,h is /&>diz$ aga9/ a pure potassium tetroxalate 7,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o7 weigh+ #j4bafb gram & requires #di4ad cc4 ,h[ _m cc4 ( wat] mu/ be add$ to #ajjj cc4 ( ! aque\s hydro*loric acid8 6,answ]63 #aa cc4 #cb4 ,h[ _m cubic c5timet]s ( #c ,n phosphoric acid mu/ be add$ to #cjj cc4 ( #j4d ,n phosphoric acid 9 ord] t ! result+ solution may be #j4f ,n8 6,answ]63 #be cc4 #cc4 ,to oxidize ! iron 9 #a gram ( ,fe,s,o#d7,,nh#d7b,,s#d4f;,h#b,o 7mol4 wgt4 #cib7 requires #c cc4 ( a giv5 solution ( ,,hno#c4 ,:at is ! normality ( ! nitric acid :5 us$ z an acid8 #f;,fe,s,o#d #b;,,hno#c #b;,h#b,,s#d #c;,fe#b7,,s#d7c #b,,no #d;,h#b,o4 6,answ]63 #j4bhce ,n4 #cd4 ,! same volume ( c>bon dioxide at ! same temp]ature & ! same pressure is lib]at$ f a #a gram sample ( dolomite1 by add+ an excess ( hydro*loric acid1 z c be lib]at$ by ! addition ( #ce cc4 ( #j4e ,n hydro*loric acid to an excess ( any pure or impure c>bonate4 ,calculate ! p]c5tage ( ,,co#b 9 ! dolomite4 6,answ]63 #ch4e4 #ce4 ,h[ _m cubic c5timet]s ( sulphuric acid 7sp4 gr4 #a4hd1 conta9+ #if ,h#b,,s#d by weight7 w be requir$ to displace ! *loride 9 ! calcium *loride =m$ by ! action ( #ajj cc4 ( #j4ajgb ,n hydro*loric acid on an excess ( calcium c>bonate1 & h[ _m grams ( ,ca,s,o#d w be =m$8 6,answ]s63 #j4bih cc42 #j4gcjj gram4 #cf4 ,potassium hydroxide :i* has be5 expos$ to ! air is f\nd on analysis to conta9 #g4fb wat]1 #b4ch ,k#b;,,co#c4 & #ij ,,koh4 ,:at weight ( residue w be obta9$ if "o gram ( ?is sample is add$ to #df cc4 ( normal hydro*loric acid & ! result+ solution1 aft] exact neutralization ) #a4jgj ,n potassium hydroxide solution1 is evaporat$ to dryness8 6,answ]63 #c4dg grams4 #cg4 ,a *emi/ receiv$ f\r diff]5t solutions1 ) ! /atem5t t !y conta9$ ei!r pure ,na,o,h2 pure ,na#b;,,co#c2 pure ,na,h,c,o#c1 or mixtures ( ^! sub/ances4 ,f ! foll[+ data id5tify !m3 ,sample ,i4 ,on add+ ph5olph?ale9 to a solution ( ! sub/ance1 x gave no color to ! solution4 ,sample ,,ii4 ,on titrat+ ) /&>d acid1 x requir$ #ae4bf cc4 = a *ange 9 color1 us+ ph5olph?ale91 & #ag4ij cc4 additional1 us+ me?yl orange z an indicator4 ,sample ,,iii4 ,! sample 0 titrat$ ) hydro*loric acid until ! p9k ( ph5olph?ale9 disappe>$1 & on ! addition ( me?yl orange ! solution 0 color$ p9k4 ,sample ,,iv4 ,on titrat+ ) hydro*loric acid1 us+ ph5olph?ale91 #ae4jj cc4 7 requir$4 ,a new sample ( ! same weight requir$ exactly #cj cc4 ( ! same acid = neutralization1 us+ me?yl orange4 6,answ]s63 7a7 ,na,h,c,o#c2 7b7 ,na,h,c,o#c,na#b;,,co#c2 7c7,na,o,h2 7d7 ,na#b;,,co#c4 #ch4 ,9 ! analysis ( a sample ( ,,khc#d;,h#d,o#f ! foll[+ data are obta9$3 ,weight sample #j4dgcb gram4 ,na,o,h solution us$ #bd4ig cc4 #c4jj cc4 ,na,o,h #a cc4 ( ,h#c,,po#d solution ( :i* #a cc4 w precipitate #j4jabbg gram ( magnesium z ,mg,n,h#d,,po#d4 ,calculate ! p]c5tage ( ,,khc#d;,h#d,o#f4 6,answ]63 #hh4fg4 #ci4 ,a "o-gram sample ( sodium hydroxide :i* has be5 expos$ to ! air = "s "t1 is dissolv$ 9 wat] & dilut$ to exactly #ejj cc4 ,"o hundr$ cubic c5timet]s ( ! solution1 :5 titrat$ ) #j4ajfb ,n hydro*loric acid1 us+ me?yl orange z an indicator1 requires #ch4fj cc4 = complete neutralization4 ,b>ium *loride 9 excess is add$ to a second portion ( #ajj cc4 ( ! solution1 :i* is dilut$ to exactly #bej cc41 all[$ to /& & filt]$4 ,two hundr$ cubic c5timet]s ( ?is filtrate require #bi4fb cc4 ( #j4ajfb ,n hydro*loric acid = neutralization1 us+ ph5olph?ale9 z an indicator4 ,calculate p]c5tage ( ,na,o,h1 ,na#b;,,co#c1 & ,h#b,o4 6,answ]s63 #gh4fc ,na,o,h2 #d4de ,na#b;,,co#c2 #af4ib ,h#b,o4 #dj4 ,a sodium hydroxide solution 7made f solid ,na,o,h :i* has be5 expos$ to ! air7 0 titrat$ aga9/ a /&>d acid us+ me?yl orange z an indicator1 & 0 f\nd to be exactly #j4a ,n4 ,?is solution 0 us$ 9 ! analysis ( a mat]ial sold at #b c5ts p] p\nd p] c5t ( an acid con/itu5t ,a1 & always mix$ s t x 0 suppos$ to conta9 #ae ( ,a1 on ! basis ( ! analy/'s report4 ,ow+ to ! c>elessness ( ! analy/'s assi/ant1 ! sodium hydroxide solution 0 us$ ) ph5olph?ale9 z an indicator 9 cold solution 9 mak+ ! analyses4 ,! conc]n manufactur+ ?is mat]ial sells #fjj tons p] ye>1 & :5 ! mi/ake 0 discov]$ x 0 e/imat$ t at ! end ( a ye> ! error 9 ! use ( indicators w\ld ei!r co/ !m or _! cu/om]s #fjjj4 ,:o w\ld lose & :y8 ,assum+ ! impure ,na,o,h us$ orig9ally 9 mak+ ! titrat+ solution consi/$ ( ,na,o,h & ,na#b;,,co#c only1 :at p] c5t ( ea* 0 pres5t8 6,answ]s63 ,cu/om] lo/2 #c4id ,na#b;,,co#c2 #if4jf ,na,o,h4 #da4 ,9 ! /&>dization ( a ,k#b;,cr#b,o#g solution aga9/ iron wire1 #ii4he pure1 #db4db cc4 ( ! solution 7 add$4 ,! weight ( ! wire us$ 0 #j4bb gram4 #c4bg cc4 ( a f]r\s sulphate solution hav+ a normal value z a r$uc+ ag5t ( #j4ajaa 7 add$ to complete ! titration4 ,calculate ! normal value ( ! ,k#b;,cr#b,o#g4 6,answ]63 #j4ajjf ,n4 #db4 ,:at weight ( iron ore conta9+ #ef4b ,fe %\ld be tak5 to /&>dize an approximately #j4a ,n oxidiz+ solution1 if n m ?an #dg cc4 are to be us$8 6,answ]63 #j4dffg gram4 #dc4 ,"o t5? gram ( iron wire1 #ii4gh pure1 is dissolv$ 9 hydro*loric acid & ! iron oxidiz$ completely ) brom9e wat]4 ,h[ _m grams ( /ann\s *loride are !re 9 a lit] ( solution if x requires #i4dg cc4 to j r$uce ! iron 9 ! above8 ,:at is ! normal value ( ! /ann\s *loride solution z a r$uc+ ag5t8 6,answ]63 #ag4ib grams2 #j4ahhh ,n4 #dd4 ,"o gram ( an oxide ( iron is fus$ ) potassium acid sulphate & ! fusion dissolv$ 9 acid4 ,! iron is r$uc$ ) /ann\s *loride1 m]curic *loride is add$1 & ! iron titrat$ ) a normal ,k#b;,cr#b,o#g solution4 #ab4id cc4 7 us$4 ,:at is ! =mula ( ! oxide1 ,fe,o1 ,fe#b,o#c1 or ,fe#c,o#d8 6,answ]63 ,fe#c,o#d4 #de4 ,if an elem5t has #ih = its atomic weight1 & aft] r$uction ) /ann\s *loride c\ld be oxidiz$ by bi*romate to a /ate correspond+ to an ,,xo#d- anion1 compute ! oxide1 or val5ce1 correspond+ to ! r$uc$ /ate f ! foll[+ data3 #j4cbff gram ( ! pure elem5t1 aft] be+ dissolv$1 0 r$uc$ ) /ann\s *loride & oxidiz$ by #dj cc4 ( ,k#b;,cr#b,o#g1 ( :i* "o cc4 #j4aifj gram ( ,fe,s,o#d7,,nh#d7b,,s#d4f;,h#b,o4 6,answ]63 ,monoval5t4 #df4 ,det]m9e ! p]c5tage ( iron 9 a sample ( limonite f ! foll[+ data3 ,sample #j4ejjj gram4 ,k,mn,o#d us$ #ej cc4 #a cc4 ,k,mn,o#d #j4jjecag gram ,fe4 ,fe,s,o#d us$ #f cc4 #a cc4 ,fe,s,o#d #j4jjibjj gram ,fe,o4 6,answ]63 #dd4fj4 #dg4 ,if #a gram ( a silicate yields #j4ejjj gram ( ,fe#b,o#c & ,al#b,o#c & ! iron pres5t requires #be cc4 ( #j4b ,n ,k,mn,o#d1 calculate ! p]c5tage ( ,fe,o & ,al#b,o#c 9 ! sample4 6,answ]63 #ce4hi ,fe,o2 #aj4jc ,al#b,o#c4 #dh4 ,a sample ( magnesia lime/one has ! foll[+ composition3 ,silica1 #c4jj2 f]ric oxide & alum9a1 #j4bj2 calcium oxide1 #cc4aj2 magnesium oxide1 #bj4gj2 c>bon dioxide1 #dc4jj4 ,9 manufactur+ lime f ! above ! c>bon dioxide is r$uc$ to #c4jj4 ,h[ _m cubic c5timet]s ( normal ,k,mn,o#d w be requir$ to det]m9e ! calcium oxide volumetrically 9 a #a gram sample ( ! lime8 6,answ]63 #bj4jh cc4 #di4 ,if #ajj cc4 ( potassium bi*romate solution 7#aj gram ,k#b;,cr#b,o#g p] lit]71 #e cc4 ( #f ,n sulphuric acid1 & #ge cc4 ( f]r\s sulphate solution 7#hj grams ,fe,s,o#d4g;,h#b,o p] lit]7 are mix$1 & ! result+ solution titrat$ ) #j4baba ,n ,k,mn,o#d1 h[ _m cubic c5timet]s ( ! ,k,mn,o#d solution w be requir$ to oxidize ! iron8 6,answ]63 #e4gj cc4 #ej4 ,if a #j4ejjj gram sample ( limonite conta9+ #ei4ej p] c5t ,fe#b,o#c requires #dj cc4 ( ,k,mn,o#d to oxidize ! iron1 :at is ! value ( #a cc4 ( ! p]manganate 9 t]ms ( 7a7 ,fe1 7b7 ,h#b;,c#b,o#d4b;,h#b,o8 6,answ]s63 7a7 #j4jjeahi gram2 7b7 #j4jjehei gram4 #ea4 ,a sample ( pyrolusite weigh+ #j4fjjj gram is treat$ ) #j4ijjj gram ( oxalic acid4 ,! excess oxalic acid requires #bc4ie cc4 ( p]manganate 7#a cc4 #j4jcjch gram ,fe,s,o#d4g;,h#b,o74 ,:at is ! p]c5tage ( ,mn,o#b1 9 ! sample8 6,answ]63 #hd4dg4 #eb4 ,a solution conta9s #ej grams ( ,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o p] lit]4 ,:at is ! normal value ( ! solution 7a7 z an acid1 & 7b7 z a r$uc+ ag5t8 6,answ]s63 7a7 #j4eijc ,n2 7b7 #j4ghgb ,n4 #ec4 ,9 ! analysis ( an iron ore conta9+ #fj ,fe#b,o#c1 a sample weigh+ #j4ejjj gram is tak5 & ! iron is r$uc$ ) sulphur\s acid4 ,on acc\nt ( failure to boil out all ! excess ,,s#b1 #ch4fj cubic c5timet]s ( #j4a ,n ,k,mn,o#d 7 requir$ to titrate ! solution4 ,:at 0 ! error1 p]c5tage error1 & :at weight ( sulphur dioxide 0 9 ! solution8 6,answ]s63 7a7 #a4fj2 7b7 #b4fg2 7c7 #j4jjcbb gram4 #ed4 ,f ! foll[+ data1 calculate ! ratio ( ! nitric acid z an oxidiz+ ag5t to ! tetroxalate solution z a r$uc+ ag5t3 #a cc4 ,,hno#c #a4bdf cc4 ,na,o,h solution2 #a cc4 ,na,o,h #a4gdc cc4 ,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o solution2 ,normal value ,na,o,h #j4ab4 6,answ]63 #d4hhe4 #ee4 ,giv5 ! foll[+ data3 #be cc4 ( a hydro*loric acid1 :5 /&>diz$ gravimetrically z silv] *loride1 yields a precipitate weigh+ #j4edfe gram4 #bd4ce cc4 ( ! hydro*loric acid are exactly equival5t to #cj4ag cc4 ( ,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o solution4 ,h[ mu* wat] mu/ be add$ to a lit] ( ! oxalate solution to make x exactly #j4jbe ,n z a r$uc+ ag5t8 6,answ]63 #eefd cc4 #ef4 ,t5 grams ( a mixture ( pure potassium tetroxalate 7,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o7 & pure oxalic acid 7,h#b;,c#b,o#d4b;,h#b,o7 are dissolv$ 9 wat] & dilut$ to exactly #ajjj cc4 ,! normal value ( ! oxalate solution :5 us$ z an acid is #j4acae4 ,calculate ! ratio ( tetroxalate to oxalate us$ 9 mak+ up ! solution & ! normal value ( ! solution z a r$uc+ ag5t4 6,answ]s63 #b3a2 #j4aegg ,n4 #eg4 ,a /ud5t /&>diz$ a solution ( ,na,o,h & "o ( ,k,mn,o#d aga9/ pure ,,khc#b,o#d4;,h#b;,c#b,o#d4b;,h#b,o & f\nd ! =m] to be #j4jgejj ,n z an alkali & ! latt] exactly #j4a ,n z an oxidiz+ ag5t4 ,by co9cid5ce1 exactly #dg4bf cc4 7 us$ 9 ea* /&>dization4 ,f9d ! ratio ( ! oxalate us$ 9 ! ,na,o,h /&>dization to ! oxalate us$ 9 ! p]manganate /&>dization4 6,answ]63 #a3a4 #eh4 ,a sample ( apatite weigh+ #j4fj gram is analyz$ = its phosphoric anhydride cont5t4 ,if ! phosphate is precipitat$ z 7,,nh#d7c,,po#d4ab,mo,o#c1 & ! precipitate 7aft] solution & r$uction ( ! ,mo,o#c to ,mo#bd,o#cg71 requires #ajj cc4 ( normal ,k,mn,o#d to oxidize x back to ,mo,o#c1 :at is ! p]c5tage ( ,p#b,o#e8 6,answ]63 #cc4ha4 #ei4 ,9 ! analysis ( a sample ( /eel weigh+ #a4hha grams ! phosphorus 0 precipitat$ ) ammonium molybdate & ! yell[ precipitate 0 dissolv$1 r$uc$ & titrat$ ) ,k,mn,o#d4 ,if ! sample conta9$ #j4jbe p] c5t ,p & #f4ja cc4 ( ,k,mn,o#d 7 us$1 to :at oxide 0 ! molybd5um r$uc$8 #a cc4 ,k,mn,o#d #j4jjgahh gram ,na#b;,c#b,o#d4 6,answ]63 ,mo#d,o#e4 #fj4 ,:at is ! value ( #a cc4 ( an iod9e solution 7#a cc4 equival5t to #j4jcjj gram ,na#b,s#b,o#c7 9 t]ms ( ,z#b,o#c8 6,answ]63 #j4jjiche gram4 #fa4 #dh cc4 ( a solution ( sodium ?iosulphate are requir$ to titrate ! iod9e lib]at$ f an excess ( potassium iodide solution by #j4cjjj gram ( pure ,,kio#c4 7,,kio#c #e,,ki #c;,h#b,,s#d #c,k#b,,s#d #c;,i#b #c;,h#b,o47 ,:at is ! normal /r5g? ( ! sodium ?iosulphate & ! value ( #a cc4 ( x 9 t]ms ( iod9e8 6,answ]s63 #j4agec ,n2 #j4jbbbd gram4 #fb4 ,"o ?\s& cubic c5timet]s ( #j4ajgi ,n sodium ?iosulphate solution is all[$ to /&4 ,"o p] c5t by weight ( ! ?iosulphate is decompos$ by ! c>bonic acid pres5t 9 ! solution4 ,to :at volume mu/ ! solution be dilut$ to make x exactly #j4a ,n z a r$uc+ ag5t8 7,na#b,s#b,o#c #b;,h#b;,,co#c ,h#b,,s#c #b,na,h,c,o#c ,s47 6,answ]63 #ajij cc4 #fc4 ,an analyz$ sample ( /ibnite conta9+ #gj4je ,sb is giv5 = analysis4 ,a /ud5t titrates x ) a solution ( iod9e ( :i* #a cc4 is equival5t to #j4jjdiej gram ( ,z#b,o#c4 ,due to an error on 8 "p 9 /&>dization1 ! /ud5t's analysis %[s ! sample to conta9 #gj4cb ,sb4 ,calculate ! true normal value ( ! iod9e solution1 & ! p]c5tage error 9 ! analysis4 6,answ]s63 #j4ajjj ,n2 #j4ci4 #fd4 ,a sample ( pyrolusite weigh+ #j4ejjj gram is treat$ ) an excess ( hydro*loric acid1 ! lib]at$ *lor9e is pass$ into potassium iodide & ! lib]at$ iod9e is titrat$ ) sodium ?iosulphate solution 7#di4ff grams ( pure ,na#b,s#b,o#c4e;,h#b,o p] lit]74 ,if #ch4gb cc4 are requir$1 :at volume ( #j4be normal p]manganate solution w be requir$ 9 an indirect det]m9ation 9 :i* a simil> sample is r$uc$ ) #j4ijab gram ,h#b;,c#b,o#d4b;,h#b,o & ! excess oxalic acid titrat$8 6,answ]63 #bf4bb cc4 #fe4 ,9 ! det]m9ation ( sulphur 9 /eel by evolv+ ! sulphur z hydrog5 sulphide1 precipitat+ cadmium sulphide by pass+ ! lib]at$ hydrog5 sulphide ?r\gh ammoniacal cadmium *loride solution1 & decompos+ ! ,cd,s ) acid 9 ! pres5ce ( a measur$ am\nt ( /&>d iod9e1 ! foll[+ data are obta9$3 ,sample1 #e4jbg grams2 cc4 ,na#b,s#b,o#c sol4 #ab4fh2 cc4 ,iod9e sol4 #ae4ei2 #a cc4 ,iod9e sol4 #a4jhf cc4 ,na#b,s#b,o#c sol42 #a cc4 ,na#b,s#b,o#c #j4jjejdd gram ,cu4 ,calculate ! p]c5tage ( sulphur4 7,h#b,s ,i#b #b;,,hi ,s47 6,answ]63 #j4ajg4 #ff4 ,giv5 ! foll[+ data1 calculate ! p]c5tage ( iron 9 a sample ( crude f]ric *loride weigh+ #a4jjj gram4 ,! iod9e lib]at$ by ! reaction #b;,fe,cl#c #b;,,hi #b;,h,cl #b;,fe,cl#b ,i#b is r$uc$ by ! addition ( #ej cc4 ( sodium ?iosulphate solution & ! excess ?iosulphate is titrat$ ) /&>d iod9e & requires #g4he cc4 #de cc4 ,i#b solution #de4ie cc4 ,na#b,s#b,o#c solution2 #de cc4 ,z#b,o#c solution #de4bg cc4 ,i#b solution4 #a cc4 ars5ite solution #j4jjeafj gram ,z#b,o#c4 6,answ]63 #bc4gg4 #fg4 ,sulphide sulphur 0 det]m9$ 9 a sample ( r$uc$ b>ium sulphate by ! evolution me?od1 9 :i* ! sulphur 0 evolv$ z hydrog5 sulphide & 0 pass$ into ,cd,cl#b solution1 ! acidifi$ precipitate be+ titrat$ ) iod9e & ?iosulphate4 ,sample1 #e4jgf grams2 cc4 ,i#b #bj4hc2 cc4 ,na#b,s#b,o#c #ab4cg2 #dc4de cc4 ,na#b,s#b,o#c #dc4db cc4 ,i#b2 #h4jf cc4 ,k,mn,o#d #dd4ff cc4 ,na#b,s#b,o#c2 #bh4hg cc4 ,k,mn,o#d #j4bjjd gram ,na#b;,c#b,o#d4 ,calculate ! p]c5tage ( sulphide sulphur 9 ! sample4 6,answ]63 #j4jej4 #fh4 ,:at weight ( pyrolusite conta9+ #hi4ba ,mn,o#b w oxidize ! same am\nt ( oxalic acid z #cg4ab cc4 ( a p]manganate solution1 ( :i* #a cc4 w lib]ate #j4jage gram ( ,i#b f ,,ki8 6,answ]63 #j4bdic gram4 #fi4 ,a sample ( pyrolusite weighs #j4bdjj gram & is #ib4ej pure ,mn,o#b4 ,! iod9e lib]at$ f ,,ki by ! manganese dioxide is suffici5t to react ) #df4bd cc4 ( ,na#b,s#b,o#c sol4 ,:at is ! normal value ( ! ?iosulphate8 6,answ]633 #j4aaje ,n4 #gj4 ,9 ! volumetric analysis ( silv] co9 7#ij ,ag71 us+ a #j4ejjj gram sample1 :at is ! lea/ normal value t a potassium ?iocyanate solution may h & n require m ?an #ej cc4 ( solution 9 ! analysis8 6,answ]63 #j4jhcci ,n4 #ga4 ,a mixture ( pure li?ium *loride & b>ium bromide weigh+ #j4f gram is treat$ ) #de4ae cubic c5timet]s ( #j4bjag ,n silv] nitrate1 & ! excess titrat$ ) #be cc4 ( #j4a ,n ,,kscn solution1 us+ f]ric alum z an indicator4 ,calculate ! p]c5tage ( brom9e 9 ! sample4 6,answ]63 #dj4aa4 #gb4 ,a mixture ( ! *lorides ( sodium & potassium f #j4ejjj gram ( a feldsp> weighs #j4aejj gram1 & aft] solution 9 wat] requires #bb4ga cc4 ( #j4ajab ,n silv] nitrate = ! precipitation ( ! *loride ions4 ,:at are ! p]c5tages ( ,na#b,o & ,k#b,o 9 ! feldsp>8 6,answ]63 #h4bd ,na#b,o2 #i4ad ,k#b,o4 ,,gravimetric ,,analysis #gc4 ,calculate 7a7 ! grams ( silv] 9 "o gram ( silv] *loride2 7b7 ! grams ( c>bon dioxide lib]at$ by ! addition ( an excess ( acid to "o gram ( calcium c>bonate2 7c7 ! grams ( ,mg,cl#b necess>y to precipitate #a gram ( ,mg,n,h#d,,po#d4 6,answ]s63 7a7 #j4gebf2 7b7 #j4dcig2 7c7 #j4fidj4 #gd4 ,calculate ! *emical factor = 7a7 ,sn 9 ,sn,o#b2 7b7 ,mg,o 9 ,mg#b,p#b,o#g2 7c7 ,p#b,o#e 9 ,mg#b,p#b,o#g2 7d7 ,fe 9 ,fe#b,o#c2 7e7 ,,s#d 9 ,ba,s,o#d4 6,answ]s63 7a7 #j4ghgi2 7b7 #j4cfbj2 7c7 #j4fcgh2 7d7 #j4fiij2 7e7 #j4daae4 #ge4 ,calculate ! log factor = 7a7 ,pb 9 ,pb,cr,o#d2 7b7 ,cr#b,o#c 9 ,pb,cr,o#d2 7c7 ,pb 9 ,pb,o#b & 7d7 ,ca,o 9 ,ca,c#b,o#d4 6,answ]s63 7a7 #i4hjfi-aj1 7b7 #i4cgac-aj2 7c7 #i4icgf-aj2 7d7 #i4fdae-aj4 #gf4 ,h[ _m grams ( ,mn#c,o#d c be obta9$ f #a gram ( ,mn,o#b8 6,answ]63 #j4hggd gram4 #gg4 ,if a sample ( silv] co9 weigh+ #j4bejj gram gives a precipitate ( ,ag,cl weigh+ #j4biia gram1 :at weight ( ,ag,i c\ld h be5 obta9$ f ! same weight ( sample1 & :at is ! p]c5tage ( silv] 9 ! co98 6,answ]s63 #j4dhih gr42 #ij4je4 #gh4 ,h[ _m cubic c5timet]s ( hydro*loric acid 7sp4 gr4 #a4ac conta9+ #be4ge ,h,cl by weight7 are requir$ to exactly neutralize #be cc4 ( ammonium hydroxide 7sp4 gr4 4#ij conta9+ #bh4cc ,,nh#c by weight78 6,answ]63 #dg4jc cc4 #gi4 ,h[ _m cubic c5timet]s ( ammonium hydroxide solution 7sp4 gr4 #j4if conta9+ #i4ia ,,nh#c by weight7 are requir$ to precipitate ! alum9ium z alum9ium hydroxide f a two-gram sample ( alum 7,k,al7,,s#d7b4ab;,h#b,o78 ,:at w be ! weight ( ! ignit$ precipitate8 6,answ]s63 #b4bf cc42 #j4baed gram4 #hj4 ,:at volume ( nitric acid 7sp4 gr4 #a4je conta9+ #i4j ,,hno#c by weight7 is requir$ to oxidize ! iron 9 "o gram ( ,fe,s,o#d4g;,h#b,o 9 ! pres5ce ( sulphuric acid8 #f;,fe,s,o#d #b;,,hno#c #c;,h#b,,s#d #c;,fe#b7,,s#d7c #b,,no #d;,h#b,o4 6,answ]63 #j4hj cc4 #ha4 ,if #j4gecj gram ( f]ric nitrate 7,fe7,,no#c7c4i;,h#b,o7 is dissolv$ 9 wat] & #a4cg cc4 ( ,h,cl 7sp4 gr4 #a4aa conta9+ #ba4ib ,h,cl by weight7 is add$1 h[ _m cubic c5timet]s ( ammonia 7sp4 gr4 #j4if conta9+ #i4ia ,,nh#c by weight7 are requir$ to neutralize ! acid & precipitate ! iron z f]ric hydroxide8 6,answ]63 #b4fc cc4 #hb4 ,to a susp5sion ( #j4cajj gram ( ,al7,,oh7#c 9 wat] are add$ #ac4jj cc4 ( aque\s ammonia 7sp4 gr4 #j4ij conta9+ #bh4d ,,nh#c by weight74 ,h[ _m cubic c5timet]s ( sulphuric acid 7sp4 gr4 #a4ah conta9+ #bd4g ,h#b,,s#d by weight7 mu/ be add$ to ! mixture 9 ord] to br+ ! alum9ium into solution8 6,answ]63 #cd4h cc4 #hc4 ,h[ _m cubic c5timet]s ( sulphur\s acid 7sp4 gr4 #a4jd conta9+ #ge grams ,,s#b p] lit]7 are requir$ to r$uce ! iron 9 #a gram ( f]ric alum 7,k,fe7,,s#d7b4ab;,h#b,o78 ,fe#b7,,s#d7c ,,s#b #b;,h#b,o #b;,fe,s,o#d #b;,h#b,,s#d4 6,answ]63 #j4he cc4 #hd4 ,h[ _m cubic c5timet]s ( a solution ( potassium bi*romate conta9+ #bf4cj grams ( ,k#b;,cr#b,o#g p] lit] mu/ be tak5 9 ord] to yield #j4fjcc gram ( ,cr#b,o#c aft] r$uction & precipitation ( ! *romium8 ,k#b;,cr#b,o#g #c,,s#b ,h#b,,s#d ,k#b,,s#d ,cr#b7,,s#d7c ,h#b,o4 6,answ]63 #dd4ci cc4 #he4 ,h[ _m cubic c5timet]s ( ammonium hydroxide 7sp4 gr4 #j4idf conta9+ #ac4hh ,,nh#c by weight7 are requir$ to precipitate ! iron z ,fe7,,oh7#c f a sample ( pure ,fe,s,o#d47,,nh#d7b,,s#d4f;,h#b,o1 :i* requires #j4cd cc4 ( nitric acid 7sp4 gr4 #a4cej conta9+ #ee4gi ,,hno#c by weight7 = oxidation ( ! iron8 7,see problem ,no4 #hj = reaction47 6,answ]63 #d4gd cc4 #hf4 ,9 ! analysis ( an iron ore by solution1 oxidation & precipitation ( ! iron z ,fe7,,oh7#c1 :at weight ( sample mu/ be tak5 = analysis s t ea* "o hundr$? ( a gram ( ! ignit$ precipitate ( ,fe#b,o#c %all repres5t "o t5? ( "o p] c5t ( iron8 6,answ]63 #f4ii grams4 #hg4 ,:at weight 9 grams ( impure f]r\s ammonium sulphate %\ld be tak5 = analysis s t ! numb] ( c5tigrams ( ,ba,s,o#d obta9$ w repres5t five times ! p]c5tage ( sulphur 9 ! sample8 6,answ]63 #j4fhgj gram4 #hh4 ,:at weight ( magnetite mu/ be tak5 = analysis 9 ord] t1 aft] precipitat+ & ignit+ all ! iron to ,fe#b,o#c1 ! p]c5tage ( ,fe#b,o#d 9 ! sample may be f\nd by multiply+ ! weight 9 grams ( ! ignit$ precipitate by #ajj8 6,answ]63 #j4iffe gram4 #hi4 ,aft] oxidiz+ ! ars5ic 9 #j4ejjj gram ( pure ,z#b,s#c to ars5ic acid1 x is precipitat$ ) magnesia mixture 7,mg,cl#b #b,,nh#d;,cl74 ,if exactly #ab4f cc4 ( ! mixture are requir$1 h[ _m grams ( ,mg,cl#b p] lit] does ! solution conta98 ,h#c;,as,o#d ,mg,cl#b #c,,nh#d,,oh ,mg,n,h#d;,as,o#d #b,,nh#d;,cl #c;,h#b,o4 6,answ]63 #cj4ga grams4 #ij4 ,a sample is prep>$ = /ud5t analysis by mix+ pure apatite 7,ca#c7,,po#d7b4;,ca,cl#b7 ) an in]t mat]ial4 ,if #a gram ( ! sample gives #j4djac gram ( ,mg#b,p#b,o#g1 h[ _m cubic c5timet]s ( ammonium oxalate solution 7conta9+ #dj grams ( 7,,nh#d7b;,c#b,o#d4;,h#b,o p] lit]7 w\ld be requir$ to precipitate ! calcium f ! same weight ( sample8 6,answ]63 #be4fj cc4 #ia4 ,if #j4fgdb gram ( a mixture ( pure magnesium c>bonate & pure calcium c>bonate1 :5 treat$ ) an excess ( hydro*loric acid1 yields #j4caag gram ( c>bon dioxide1 calculate ! p]c5tage ( magnesium oxide & ( calcium oxide 9 ! sample4 6,answ]s63 #ac4bb ,mg,o2 #dj4ed ,ca,o4 #ib4 ,! calcium 9 a sample ( dolomite weigh+ #j4ichj gram is precipitat$ z calcium oxalate & ignit$ to calcium oxide4 ,:at volume ( gas1 measur$ ov] wat] at #bj;,c4 & #gfe mm4 pressure1 is giv5 (f dur+ ignition1 if ! result+ oxide weighs #j4bfjf gram8 7,g4,m4,v4 #bb4d lit]s2 ,v4,p4 wat] at #bj;,c4 #ag4d mm47 6,answ]63 #bbg cc4 #ic4 ,a lime/one is f\nd to conta9 #ic4je ,ca,c,o#c1 & #e4af ,mg,c,o#c4 ,calculate ! weight ( ,ca,o obta9able f #c tons ( ! lime/one1 assum+ complete conv]sion to oxide4 ,:at weight ( ,mg#b,p#b,o#g c\ld be obta9$ f a #c-;gram sample ( ! lime/one8 6,answ]s63 #a4efe tons2 #j4bjdd gram4 #id4 ,a sample ( dolomite is analyz$ = calcium by precipitat+ z ! oxalate & ignit+ ! precipitate4 ,! ignit$ product is assum$ to be ,ca,o & ! analy/ reports #bi4ej ,ca 9 ! sample4 ,ow+ to insuffici5t ignition1 ! product actually conta9$ #h ( its weight ( ,ca,c,o#c4 ,:at is ! correct p]c5tage ( calcium 9 ! sample1 & :at is ! p]c5tage error8 6,answ]s63 #bh4df2 #c4fe error4 #ie4 ,:at weight ( impure calcite 7,ca,c,o#c7 %\ld be tak5 = analysis s t ! volume 9 cubic c5timet]s ( ,,co#b obta9$ by treat+ ) acid1 measur$ dry at #ah;,c4 & #gfc mm41 %all equal ! p]c5tage ( ,ca,o 9 ! sample8 6,answ]63 #j4bcei gram4 #if4 ,h[ _m cubic c5timet]s ( ,,hno#c 7sp4 gr4 #a4ac conta9+ #ba4j ,,hno#c by weight7 are requir$ to dissolve #e grams ( brass1 conta9+ #j4fa ,pb1 #bd4ci ,zn1 & #ge ,cu1 assum+ r$uction ( ! nitric acid to ,,no by ea* con/itu5t8 ,:at fraction ( ?is volume ( acid is us$ = oxidation8 6,answ]s63 #ee4jf cc42 #be4 #ig4 ,:at weight ( metallic copp] w be deposit$ f a cupric salt solution by a curr5t ( #a4e amp]es dur+ a p]iod ( #de m9utes1 assum+ #ajj curr5t effici5cy8 7#a ,f>aday #if1ejj c\lombs47 6,answ]63 #a4cce grams4 #ih4 ,9 ! electrolysis ( a #j4hjjj gram sample ( brass1 !re is obta9$ #j4jjcj gram ( ,pb,o#b1 & a deposit ( metallic copp] exactly equal 9 weight to ! ignit$ precipitate ( ,zn#b,p#b,o#g subsequ5tly obta9$ f ! solution4 ,:at is ! p]c5tage composition ( ! brass8 6,answ]s63 #fi4ge ,cu2 #bi4ib ,zn2 #j4cc ,pb4 #ii4 ,a sample ( brass 7#fh4ij ,cu2 #a4aj ,pb & #cj4jj ,zn7 weigh+ #j4idjj gram is dissolv$ 9 nitric acid4 ,! lead is det]m9$ by weigh+ z ,pb,s,o#d1 ! copp] by electrolysis & ! z9c by precipitation ) 7,,nh#d7b;,,hpo#d 9 a neutral solution4 7a7 ,calculate ! cubic c5timet]s ( nitric acid 7sp4 gr4 #a4db conta9+ #fi4ij ,,hno#c by weight7 requir$ to j dissolve ! brass1 assum+ r$uction to ,,no4 6,answ]63 #b4dh cc4 7b7 ,calculate ! cubic c5timet]s ( sulphuric acid 7sp4 gr4 #a4hd conta9+ #id ,h#b,,s#d by weight7 to displace ! nitric acid4 6,answ]63 #j4hc cc4 7c7 ,calculate ! weight ( ,pb,s,o#d4 6,answ]63 #j4jaeb gram4 7d7 ,! clean electrode weighs #aj4ifdj grams4 ,calculate ! weight aft] ! copp] has be5 deposit$4 6,answ]63 #aa4faaf grams4 7e7 ,calculate ! grams ( 7,,nh#d7b;,,hpo#d requir$ to precipitate ! z9c z ,zn,n,h#d,,po#d4 6,answ]63 #j4egje gram4 7f7 ,calculate ! weight ( ignit$ ,zn#b,p#b,o#g4 6,answ]63 #j4fegc gram4 #ajj4 ,if 9 ! analysis ( a brass conta9+ #bh4jj z9c an error is made 9 weigh+ a #b4e gram portion by :i* #j4jja gram too mu* is weigh$ out1 :at p]c5tage error 9 ! z9c det]m9ation w\ld result8 ,:at volume ( a solution ( sodium hydrog5 phosphate1 conta9+ #ij grams ( ,na#b;,,hpo#d4ab;,h#b,o p] lit]1 w\ld be requir$ to precipitate ! z9c z ,zn,n,h#d,,po#d & :at weight ( precipitate w\ld be obta9$8 6,answ]s63 7a7 #j4jd error2 7b7 #ci4ig cc42 7c7 #a4iji grams4 #aja4 ,a sample ( magnesium c>bonate1 contam9at$ ) ,si,o#b z its only impurity1 weighs #j4ejjj gram & loses #j4ajjj gram on ignition4 ,:at volume ( disodium phosphate solution 7conta9+ #ij grams ,na#b;,,hpo#d4ab;,h#b,o p] lit]7 w be requir$ to precipitate ! magnesium z magnesium ammonium phosphate8 6,answ]63 #i4jg cc4 #ajb4 #b4fb cubic c5timet]s ( nitric acid 7sp4 gr4 #a4db conta9+ #fi4hj ,,hno#b by weight7 are requir$ to j dissolve a sample ( brass conta9+ #fi4bg ,cu2 #j4je ,pb2 #j4jg ,fe2 & #cj4fa ,zn4 ,assum+ ! acid us$ z oxidiz+ ag5t 0 r$uc$ to ,,no 9 e case1 calculate ! weight ( ! brass & ! cubic c5timet]s ( acid us$ z acid4 6,answ]63 #j4iib gram2 #a4ig cc4 #ajc4 ,"o gram ( a mixture ( silv] *loride & silv] bromide is f\nd to conta9 #j4ffce gram ( silv]4 ,:at is ! p]c5tage ( brom9e8 6,answ]63 #ba4cj4 #ajd4 ,a precipitate ( silv] *loride & silv] bromide weighs #j4hacb gram4 ,on heat+ 9 a curr5t ( *lor9e1 ! silv] bromide is conv]t$ to silv] *loride1 & ! mixture loses #j4adej gram 9 weight4 ,calculate ! p]c5tage ( *lor9e 9 ! orig9al precipitate4 6,answ]63 #f4ac4 #aje4 ,a sample ( feldsp> weigh+ #a4jjj gram is fus$ & ! silica det]m9$4 ,! weight ( silica is #j4fdfj gram4 ,?is is fus$ ) #d grams ( sodium c>bonate4 ,h[ _m grams ( ! c>bonate actually comb9$ ) ! silica 9 fusion1 & :at 0 ! loss 9 weight due to c>bon dioxide dur+ ! fusion8 6,answ]s63 #a4ace grams2 #j4dgae gram4 #ajf4 ,a mixture ( b>ium oxide & calcium oxide weigh+ #b4babj grams is trans=m$ into mix$ sulphates1 weigh+ #e4jbc grams4 ,calculate ! grams ( calcium oxide & b>ium oxide 9 ! mixture4 6,answ]s63 #a4hbd grams ,ca,o2 #j4chgg gram ,ba,o4 ,,app5dix ,,electrolytic ,,dissociation ,,!ory ,! foll[+ brief /atem5ts conc]n+ ! ionic !ory & a few ( its applications are int5d$ = ref]5ce 9 connection ) ! explanations :i* are giv5 9 ! ,notes accompany+ ! v>i\s proc$ures4 ,! read] :o desires a m ext5d$ discussion ( ! fundam5tal !ory & its uses is ref]r$ to su* books z ,talbot & ,blan*>d's 6,electrolytic ,dissociation ,!ory6 7,macmillan ,company71 or ,alex&] ,smi?'s 6,introduction to ,g5]al ,inorganic ,*emi/ry6 7,c5tury ,company74 ,! 6electrolytic dissociation !ory61 z prop\nd$ by ,arrh5ius 9 #ahhg1 assumes t acids1 bases1 & salts 7t is1 electrolytes7 9 aque\s solution are dissociat$ to a great] or less ext5t into 6ions64 ,^! ions are assum$ to be electrically *>g$ atoms or gr\ps ( atoms1 z1 = example1 ,h & ,br- f hydrobromic acid1 ,na & ,,oh- f sodium hydroxide1 #b,,nh#d & ,,s#d-- f ammonium sulphate4 ,! unit *>ge is t :i* is dissociat$ ) a hydrog5 ion4 ,^? ^u o!r ions v>y 9 sign & numb] accord+ to ! *emical "* & val5ce ( ! atoms or radicals ( :i* ! ions are compos$4 ,9 any solution ! aggregate ( ! positive *>ges ^u ! positive ions 76cations67 mu/ always balance ! aggregate negative *>ges ^u ! negative ions 76anions674 ,x is assum$ t ! ,na ion1 = example1 diff]s f ! sodium atom 9 behavior because ( ! v consid]able electrical *>ge :i* x c>ries & :i*1 z j /at$1 mu/1 9 an electrically neutral solution1 be balanc$ by a correspond+ negative *>ge on "s o!r ion4 ,:5 an electric curr5t is pass$ ?r\gh a solution ( an electrolyte ! ions move ) & convey ! curr5t1 & :5 ! cations come into contact ) ! negatively *>g$ ca?ode !y lose _! *>ges1 & ! result+ electrically neutral atoms 7or radicals7 are lib]at$ z su*1 or else ent] at once into *emical reaction ) ! compon5ts ( ! solution4 ,two ions ( id5tically ! same composition b ) diff]5t electrical *>ges may exhibit widely diff]5t prop]ties4 ,= example1 ! ion ,mn,o#d- f p]manganates yields a purple-r$ solution & diff]s 9 its *emical behavior f ! ion ,mn,o#d-- f manganates1 ! solutions ( :i* are gre54 ,! *emical *anges ^u :i* ! proc$ures ( analytical *emi/ry dep5d are almo/ exclusively ^? 9 :i* ! react+ sub/ances are electrolytes1 & analytical *emi/ry is1 !re=e1 ess5tially ! *emi/ry ( ! ions4 ,! p]c5tage dissociation ( ! same electrolyte t5ds to increase ) increas+ dilution ( its solution1 al?\gh n 9 direct proportion4 ,! p]c5tage dissociation ( diff]5t electrolytes 9 solutions ( equival5t conc5trations 7su*1 = example1 z normal solutions7 v>ies widely1 z is indicat$ 9 ! foll[+ tables1 9 :i* approximate figures are giv5 = t5?-normal solutions at a temp]ature ( ab\t #ah;,c4 ,,acids ,,sub/ance ,,p]c5tage ,,dissociation ,,9 #j4a ,,equival5t ,,solution ,h,cl1 ,h,br1 ,,hi1 ,,hno#c #ij ,h,cl,o#c1 ,h,cl,o#d1 ,h,mn,o#d #ij ,h#b,,s#d -- ,h ,,hso#d- #ij ,h#b;,c#b,o#d -- ,h ,,hc#b,o#d- #ej ,h#b,,s#c -- ,h ,,hso#c- #bj ,h#c,,po#d -- ,h ,h#b,,po#d- #bg ,h#b,,po#d- -- ,h ,,hpo#d-- #j4b ,h#c;,as,o#d -- ,h ,h#b;,as,o#d- #bj ,,hf #i ,,hc#b;,h#c,o#b #a4d ,h#b;,,co#c -- ,h ,,hco#c- #j4ab ,h#b,s -- ,h ,,hs- #j4je ,,hcn #j4ja ,,bases ,,sub/ance ,,p]c5tage ,,dissociation ,,9 #j4a ,,equival5t ,,solution ,,koh1 ,na,o,h #hf ,ba7,,oh7#b #ge ,,nh#d,,oh #a4d ,,salts ,,type ,,( ,,salt ,,p]c5tage ,,dissociation ,,9 #j4a ,,equival5t ,,solution ,r,r- #hf ,r7,r-7#b #gb 7,r7#b,r-- #gb ,r,r-- #de ,! p]c5tage dissociation is det]m9$ by /udy+ ! electrical conductivity ( ! solutions & by o!r physico-*emical me?ods1 & ! foll[+ g5]al /atem5ts summ>ize ! results3 6,salts61 z a class1 are l>gely dissociat$ 9 aque\s solution4 6,acids6 yield ,h ions 9 wat] solution1 & ! comp>ative 6/r5g?61 t is1 ! activity1 ( acids is proportional to ! conc5tration ( ! ,h ions & is measur$ by ! p]c5tage dissociation 9 solutions ( equival5t conc5tration4 ,! common m9]al acids are l>gely dissociat$ & !re=e give a relatively high conc5tration ( ,h ions1 & are commonly kn[n z /rong acids4 ,! organic acids1 on ! o!r h&1 belong g5]ally to ! gr\p ( weak acids4 6,bases6 yield ,,oh- ions 9 wat] solution1 & ! comp>ative /r5g? ( ! bases is measur$ by _! relative dissociation 9 solutions ( equival5t conc5tration4 ,ammonium hydroxide is a weak base1 z %[n 9 ! table above1 :ile ! hydroxides ( sodium & potassium exhibit /rongly basic prop]ties4 ,ionic reactions are all1 to a great] or less degree1 6rev]sible reactions64 ,a typical example ( an easily rev]sible reaction is t repres5t+ ! *anges 9 ionization :i* an electrolyte su* z acetic acid und]goes on dilution or conc5tration ( its solutions1 6i4e461 ,,hc#b;,h#c,o#b -- ,h ,c#b;,h#c,o#b-4 ,z 0 /at$ above1 ! ionization increases ) dilution1 ! reaction !n proce$+ f left to "r1 :ile conc5tration ( ! solution occasions a p>tial reassociation ( ! ions1 & ! reaction proce$s f "r to left4 ,to und]/& ! pr9ciple und]ly+ ^! *anges x is necess>y to consid] fir/ ! conditions :i* prevail :5 a solution ( acetic acid1 :i* has be5 /irr$ until x is ( uni=m conc5tration ?r\gh\t1 has come to a con/ant temp]ature4 ,a c>eful /udy ( su* solutions has %[n t !re is a def9ite /ate ( equilibrium betwe5 ! con/itu5ts ( ! solution2 t is1 !re is a def9ite relation betwe5 ! undissociat$ acetic acid & its ions1 :i* is *>act]i/ic = ! prevail+ conditions4 ,x is n1 h[ev]1 assum$ t ?is is a condition ( /atic equilibrium1 b r t !re is cont9ual dissociation & association1 z repres5t$ by ! oppos+ reactions1 ! app>5t condition ( re/ result+ f ! fact t ! am\nt ( *ange 9 "o direction dur+ a giv5 "t is exactly equal to t 9 ! opposite direction4 ,a quantitative /udy ( ! am\nt ( undissociat$ acid1 & ( ,h ions & ,c#b;,h#c,o#b- ions actually to be f\nd 9 a l>ge numb] ( solutions ( acetic acid ( v>y+ dilution 7assum+ !m to be 9 a condition ( equilibrium at a common temp]ature71 has %[n t !re is always a def9ite relation betwe5 ^! ?ree quantities :i* may be express$ ?us3 76,conc'n ,h x ,conc'n ,c#b;,h#c,o#b-7_/;,conc'n ,,hc#b;,h#c,o#b ,con/ant64 ,9 o!r words1 !re is always a def9ite & con/ant ratio betwe5 ! product ( ! conc5trations ( ! ions & ! conc5tration ( ! undissociat$ acid :5 conditions ( equilibrium prevail4 ,x has be5 f\nd1 fur!r1 t a simil> /atem5t may be made reg>d+ all rev]sible reactions1 :i* may be express$ 9 g5]al t]ms ?us3 ,! rate ( *emical *ange is proportional to ! product ( ! conc5trations ( ! sub/ances tak+ "p 9 ! reaction2 or1 if conditions ( equilibrium are consid]$ 9 :i*1 z /at$1 ! rate ( *ange 9 opposite directions is assum$ to be equal1 !n ! product ( ! conc5trations ( ! sub/ances ent]+ into ! reaction /&s 9 a con/ant ratio to ! product ( ! conc5trations ( ! result+ sub/ances1 z giv5 9 ! expression above = ! solutions ( acetic acid4 ,?is pr9ciple is call$ ! 6,law ( ,mass ,action64 ,x %\ld be borne 9 m9d t ! expression above = acetic acid applies to a wide range ( dilutions1 provid$ ! temp]ature rema9s con/ant4 ,if ! temp]ature *anges ! value ( ! con/ant *anges some:at1 b is aga9 uni=m = diff]5t dilutions at t temp]ature4 ,! foll[+ data are giv5 = temp]atures ( ab\t #ah;,c4#a ,,molal ,,fraction ,,molal ,,conc5tra- ,,molal ,,conc5tra- ,,value ,,( ,,conc5tration ,,ioniz$ ,,tion ,,( ,h ,,& ,,tion ,,( ,,undis- ,,con/ant ,,con/ant ,,acetate- ,,ions ,,sociat$ ,,acid #a4j 4#jjd 4#jjd 4#iif 4#jjjjafa #j4a 4#jac 4#jjac 4#jihg 4#jjjjaga #j4ja 4#jdjg 4#jjjdjg 4#jjieic 4#jjjjagb ,footnote #a3 ,alex&] ,smi?1 6,g5]al ,inorganic ,*emi/ry61 p4 #egi4 ,! molal conc5trations giv5 9 ! table ref] to fractions ( a gram-molecule p] lit] ( ! undissociat$ acid1 & to fractions ( ! correspond+ quantities ( ,h & ,c#b;,h#c,o#b- ions p] lit] :i* w\ld result f ! complete dissociation ( a gram-molecule ( acetic acid4 ,! values calculat$ = ! con/ant are subject to "s v>iation on acc\nt ( exp]im5tal errors 9 det]m9+ ! p]c5tage ioniz$ 9 ea* case1 b ! approximate agreem5t betwe5 ! values f\nd = molal & c5timolal 7"o hundr$fold dilution7 is significant4 ,! figures giv5 also illu/rate ! g5]al pr9ciple1 t ! 6relative6 ionization ( an electrolyte increases ) ! dilution ( its solution4 ,if we consid] :at happ5s dur+ ! 7usually7 brief p]iod ( dilution ( ! solution f molal to #j4a molal1 = example1 x w be se5 t on ! addition ( wat] ! conditions ( conc5tration :i* l$ to equality 9 ! rate ( *ange1 & h5ce to equilibrium 9 ! molal solution1 cease to exi/2 & s9ce ! dissociat+ t5d5cy increases ) dilution1 z j /at$1 x is true at ! fir/ in/ant aft] ! addition ( wat] t ! conc5tration ( ! undissociat$ acid is too great to be p]man5t "u ! new conditions ( dilution1 & ! reaction1 ,,hc#b;,h#c,o#b -- ,h ,c#b;,h#c,o#b-1 w proce$ f left to "r ) great rapidity until ! respective conc5trations adju/ !mselves to ! new conditions4 ,t :i* is true ( ?is reaction is also true ( all rev]sible reactions1 namely1 t any *ange ( conditions :i* occasions an increase or a decrease 9 conc5tration ( "o or m ( ! compon5ts causes ! reaction to proce$ 9 "o direction or ! o!r until a new /ate ( equilibrium is e/abli%$4 ,?is pr9ciple is con/antly appli$ ?r\gh\t ! discussion ( ! applications ( ! ionic !ory 9 analytical *emi/ry1 & x %\ld be cle>ly und]/ood t :5ev] an exi/+ /ate ( equilibrium is di/urb$ z a result ( *anges ( dilution or temp]ature1 or z a consequ5ce ( *emical *anges :i* br+ into action any ( ! con/itu5ts ( ! solution1 ?us alt]+ _! conc5trations1 !re is always a t5d5cy to re-e/abli% ?is equilibrium 9 accordance ) ! law4 ,?us1 if a base is add$ to ! solution ( acetic acid ! ,h ions !n unite ) ! ,,oh- ions f ! base to =m undissociat$ wat]4 ,! conc5tration ( ! ,h ions is ?us dim9i%$1 & m ( ! acid dissociates 9 an attempt to re/ore equilbrium1 until f9ally practically all ! acid is dissociat$ & neutraliz$4 ,simil> conditions prevail :51 = example1 silv] ions react ) *loride ions1 or b>ium ions react ) sulphate ions4 ,9 ! =m] case ! dissociation reaction ( ! silv] nitrate is ,ag,n,o#c -- ,ag ,,no#c-1 & z soon z ! ,ag ions unite ) ! ,cl- ions ! conc5tration ( ! =m] is dim9i%$1 m ( ! ,ag,n,o#c dissociates1 & ?is process goes on until ! ,ag ions are practically all remov$ f ! solution1 if ! ,cl- ions are pres5t 9 suffici5t quantity4 ,= ! sake ( accuracy x %\ld be /at$ t ! mass law _c be rigidly appli$ to solutions ( ^? electrolytes :i* are l>gely dissociat$4 ,:ile ! explanation ( ! deviation f quantitative exactness 9 ^! cases is n kn[n1 ! law is /ill ( m>k$ s]vice 9 develop+ analytical me?ods along m logical l9es ?an 0 =m]ly practicable4 ,x has n seem$ wise to qualify ea* /atem5t made 9 ! ,notes to indicate ?is lack ( quantitative exactness4 ,! /ud5t %\ld recognize its exi/5ce1 h[ev]1 & w realize its significance bett] z 8 k ( physical *emi/ry increases4 ,if we apply ! mass law to ! case ( a sub/ance ( small solubility1 su* z ! comp\nds usually precipitat$ 9 quantitative analysis1 we d]ive :at is kn[n z ! 6solubility product61 z foll[s3 ,tak+ silv] *loride z an example1 & rememb]+ t x is n absolutely insoluble 9 wat]1 ! equilibrium expression = its solution is3 76,conc'n ,ag x ,conc'n ,cl-7_/,conc'n ,ag,cl ,con/ant64 ,b su* a solution ( silv] *loride :i* is 9 contact ) ! solid precipitate mu/ be saturat$ = ! exi/+ temp]ature1 & ! quantity ( undissociat$ ,ag,cl 9 ! solution is def9ite & con/ant = t temp]ature4 ,s9ce x is a con/ant1 x may be elim9at$1 & ! expression becomes 6,conc'n ,ag x ,conc'n ,cl- ,con/ant61 & ?is is kn[n z ! solubility product4 ,no precipitation ( a specific sub/ance w occur until ! product ( ! conc5trations ( its ions 9 a solution exce$s ! solubility product = t sub/ance2 :5ev] t product is exce$$ precipitation mu/ foll[4 ,x w readily be se5 t if a sub/ance :i* yields an ion 9 common ) ! precipitat$ comp\nd is add$ to su* a solution z has j be5 describ$1 ! conc5tration ( t ion is increas$1 & z a result ! conc5tration ( ! o!r ion mu/ proportionately decrease1 :i* c only occur ?r\gh ! =mation ( "s ( ! undissociat$ comp\nd :i* mu/ sep>ate f ! already saturat$ solution4 ,?is expla9s :y ! addition ( an excess ( ! precipitant is (t5 advantage\s 9 quantitative proc$ures4 ,su* a case is discuss$ at l5g? 9 ,note #b on page #aac4 ,simil>ly1 ! ionization ( a specific sub/ance 9 solution t5ds to dim9i% on ! addition ( ano!r sub/ance ) a common ion1 z1 = in/ance1 ! addition ( hydro*loric acid to a solution ( hydrog5 sulphide4 ,hydrog5 sulphide is a weak acid1 & ! conc5tration ( ! hydrog5 ions 9 its aque\s solutions is v small4 ,! equilibrium 9 su* a solution may be repres5t$ z3 767,conc'n ,h7#b x ,conc'n ,s--7_/,conc'n ,h#b,s ,con/ant61 & a m>k$ increase 9 ! conc5tration ( ! ,h ions1 su* z w\ld result f ! addition ( ev5 a small am\nt ( ! highly ioniz$ hydro*loric acid1 displaces ! po9t ( equilibrium & "s ( ! ,s-- ions unite ) ,h ions to =m undissociat$ ,h#b,s4 ,?is is ( mu* importance 9 /udy+ ! reactions 9 :i* hydrog5 sulphide is employ$1 z 9 qualitative analysis4 ,by a p>allel c\rse ( reason+ x w be se5 t ! addition ( a salt ( a weak acid or base to solutions ( t acid or base make x1 9 effect1 /ill weak] because !y decrease its p]c5tage ionization4 ,to und]/& ! *anges :i* occur :5 solids are dissolv$ :]e *emical action is involv$1 x %\ld be rememb]$ t no sub/ance is completely insoluble 9 wat]1 & t ^? products ( a *emical *ange :i* are lea/ dissociat$ w fir/ =m4 ,consid]1 = example1 ! action ( hydro*loric acid ^u magnesium hydroxide4 ,! m9ute quantity ( dissolv$ hydroxide dissociates ?us3 ,mg7,,oh7#b -- ,mg #b,,oh-4 ,:5 ! acid is introduc$1 ! ,h ions ( ! acid unite ) ! ,,oh- ions to =m undissociat$ wat]4 ,! conc5tration ( ! ,,oh- ions is ?us dim9i%$1 m ,mg7,,oh7#b dissociates1 ! solution is no long] saturat$ ) ! undissociat$ comp\nd1 & m ( ! solid dissolves4 ,?is process repeats itself ) great rapidity until1 if suffici5t acid is pres5t1 ! solid passes completely into solution4 ,exactly ! same sort ( process takes place if calcium oxalate1 = example1 is dissolv$ 9 hydro*loric acid4 ,! ,c#b,o#d-- ions unite ) ! ,h ions to =m undissociat$ oxalic acid1 ! acid be+ less dissociat$ ?an normally 9 ! pres5ce ( ! ,h ions f ! hydro*loric acid 7see /atem5ts reg>d+ hydrog5 sulphide above74 ,z ! undissociat$ oxalic acid =ms1 ! conc5tration ( ! ,c#b,o#d-- ions less5s & m ,ca,c#b,o#d dissolves1 z describ$ = ! ,mg7,,oh7#b above4 ,num]\s in/ances ( ! applications ( ^! pr9ciples are giv5 9 ! ,notes4 ,wat] itself is slightly dissociat$1 & al?\gh ! result+ ,h & ,,oh- ions are pres5t only 9 m9ute conc5trations 7#a mol4 ( dissociat$ wat] 9 #ajg lit]s71 yet "u "s conditions !y may give rise to important consequ5ces4 ,! t]m 6hydrolysis6 is appli$ to ! *anges :i* result f ! reaction ( ^! ions4 ,any salt :i* is d]iv$ f a weak base or a weak acid 7or bo?7 is subject to hydrolytic action4 ,potassium cyanide1 = example1 :5 dissolv$ 9 wat] gives an alkal9e solution because "s ( ! ,h ions f ! wat] unite ) ,,cn- ions to =m 7,,hcn71 :i* is a v weak acid1 & is b v slightly dissociat$4 ,potassium hydroxide1 :i* might =m f ! ,,oh- ions1 is s l>gely dissociat$ t ! ,,oh- ions rema9 z su* 9 ! solution4 ,! union ( ! ,h ions ) ! ,,cn- ions to =m ! undissociat$ ,,hcn dim9i%es ! conc5tration ( ! ,h ions1 & m wat] dissociates 7,h#b,o -- ,h ,,oh-7 to re/ore ! equilibrium4 ,x is cle>1 h[ev]1 t !re mu/ be a gradual accumulation ( ,,oh- ions 9 ! solution z a result ( ^! *anges1 caus+ ! solution to exhibit an alkal9e reaction1 & also t ultimately ! fur!r dissociation ( ! wat] w be *eck$ by ! pres5ce ( ^! ions1 j z ! dissociation ( ! ,h#b,s 0 less5$ by ! addition ( ,h,cl4 ,an exactly opposite result foll[s ! solution ( su* a salt z ,al#b7,,s#d7c 9 wat]4 ,9 ?is case ! acid is /rong & ! base weak1 & ! ,,oh- ions =m ! little dissociat$ ,al7,,oh7#c1 :ile ! ,h ions rema9 z su* 9 ! solution1 sulphuric acid be+ ext5sively dissociat$4 ,! solution exhibits an acid reaction4 ,su* hydrolytic processes z ! above are ( great importance 9 analytical *emi/ry1 especially 9 ! und]/&+ ( ! action ( indicators 9 volumetric analysis4 7,see page #cb47 ,! impell+ =ce :i* causes an elem5t to pass f ! atomic to ! ionic condition is t]m$ 6electrolytic solution pressure61 or ionization t5sion4 ,?is =ce may be measur$ 9 t]ms ( electrical pot5tial1 & ! table bel[ %[s ! relative values = a numb] ( elem5ts4 ,9 g5]al1 an elem5t ) a great] solution pressure t5ds to cause ! deposition ( an elem5t ( less solution pressure :5 plac$ 9 a solution ( its salt1 z1 = in/ance1 :5 a /rip ( z9c or iron is plac$ 9 a solution ( a copp] salt1 ) ! result+ precipitation ( metallic copp]4 ,hydrog5 is includ$ 9 ! table1 & its position %\ld be not$ ) ref]5ce to ! o!r common elem5ts4 ,= a m ext5d$ discussion ( ?is topic ! /ud5t %\ld ref] to o!r treatises4 ,,pot5tial ,,s]ies ,,( ,,! ,,metals ,,pot5tial ,,pot5tial ,,9 ,,volts ,,9 ,,volts ,sodium ,na #b4dd ,lead ,pb -#j4ac ,calcium ,ca ,hydrog5 ,h -#j4bh ,magnesium ,mg ,bismu? ,bi ,alum9um ,a#a #a4jj ,antimony -#j4ge ,manganese ,mn ,ars5ic ,z9c ,zn #j4di ,copp] ,cu -#j4fa ,cadmium ,cd #j4ad ,m]cury ,hg -#a4jc ,iron ,fe #j4jfc ,silv] ,ag -#a4je ,cobalt ,co -#j4jde ,plat9um ,nickel ,ni -#j4jdi ,gold ,t9 ,sn -#j4jhe787 ,,! ,,fold+ ,,( ,a ,,filt] ,,pap] ,if a filt] pap] is fold$ along its diamet]1 & aga9 fold$ along ! radius at "r angles to ! orig9al fold1 a cone is =m$ on op5+1 ! angle ( :i* is #fj4 ,funnels = analytical use are suppos$ to h ! same angle1 b are r>ely accurate4 ,x is possible1 h[ev]1 ) c>e1 to fit a filt] ?us fold$ into a funnel 9 su* a way z to prev5t air f pass+ d[n betwe5 ! pap] & ! funnel to break ! column ( liquid 9 ! /em1 :i* aids greatly1 by its g5tle suction1 9 promot+ ! rate ( filtration4 ,su* a filt] has1 h[ev]1 ! disadvantage t !re are ?ree ?icknesses ( pap] back ( half ( its filt]+ surface1 z a consequ5ce ( :i* "o half ( a precipitate wa%es or dra9s m sl[ly4 ,mu* "t may be sav$ 9 ! aggregate by le>n+ to fold a filt] 9 su* a way z to improve its effective filt]+ surface4 ,! directions :i* foll[1 ?\gh app>5tly complicat$ on fir/ read+1 are easily appli$ & easily rememb]$4 ,use a #f-;in* filt] = practice4 ,place f\r dots on ! filt]1 two ea* on diamet]s :i* are at "r angles to ea* o!r4 ,!n proce$ z foll[s3 7#a7 ,fold ! filt] ev5ly across "o ( ! diamet]s1 creas+ x c>efully2 7#b7 op5 ! pap]1 turn x ov]1 rotate x #ij to ! "r1 br+ ! edges toge!r & crease along ! o!r diamet]2 7#c7 op51 & rotate #de to ! "r1 br+ edges toge!r1 & crease ev5ly2 7#d7 op51 & rotate #ij to ! "r1 & crease ev5ly2 7#e7 op51 turn ! filt] ov]1 rotate #bb-7a_/b7 to ! "r1 & crease ev5ly2 7#f7 op51 rotate #de to ! "r & crease ev5ly2 7#g7 op51 rotate #de to ! "r & crease ev5ly2 7#h7 op51 rotate #de to ! "r & crease ev5ly2 7#i7 op5 ! filt]1 &1 />t+ ) "o ( ! dots betwe5 ?umb & =ef+] ( ! "r h&1 fold ! second crease to ! left ov] on x1 & d ! same ) ea* ( ! o!r dots4 ,place x1 ?us fold$1 9 ! funnel1 moi/5 x1 & fit to ! side ( ! funnel4 ,! filt] w !n h f\r %ort segm5ts :]e !re are ?ree ?icknesses & f\r :]e !re is "o ?ickness1 b ! latt] are ev5ly di/ribut$ ar\nd its circumf]5ce1 ?us greatly aid+ ! passage ( liquids ?r\gh ! pap] & ha/5+ bo? filtration & wa%+ ( ! :ole cont5ts ( ! filt]4 6,,sample ,,pages ,,= ,,laboratory ,,records6 6,page ,a6 ,date ,,calibration ,,( ,,burette ,no4 ,,burette ,,diff]5ce ,,obs]v$ ,,diff]5ce ,,calculat$ ,,read+s ,,weights ,,correction #j4jb #af4bg #aj4ab #aj4aj #bf4ce #aj4jh -4#jb #bj4ji #i4ig #cf4bf #i4ia -4#jf #cj4af #aj4jg #df4cd #aj4jh 4#ja #dj4ai #aj4jc #ef4ca #i4ig -4#jf #ej4jj #i4ha #ff4ag #i4hf 4#je ,^! data to be obta9$ 9 duplicate = ea* burette4 6,page ,b6 ,date ,,det]m9ation ,,( ,,comp>ative ,,/r5g? ,h,cl vs4 ,na,o,h ,,det]m9ation ,i ,,ii ,correct$ ,correct$ ,f9al ,read+ ,h,cl #dh4ag #dh4jh #dc4bj #dc4ad ,initial ,read+ ,h,cl #j4ab 4#ab 4#ag 4#ag ----- ----- ----- ----- #dg4if #db4ig ,correct$ ,correct$ ,f9al ,read+ ,h,cl #df4cf #df4bi #dj4ea #dj4cg ,initial ,read+ ,h,cl #a4ge #a4ge 4#ej 4#ej ----- ----- ----- ----- #dd4ed #ci4hg log cc4 ,na,o,h #a4fdfh #a4fjjh colog cc4 ,h,cl #h4caib #h4cffh ------ ------ #i4ifhj - #aj #i4ifgf - #aj #a cc4 ,h,cl 4#ibij cc4 ,na,o,h 4#ibhb cc4 ,na,o,h ,mean 4#ibhf ,sign$ 6,page ,c6 ,date ,,/&>dization ,,( ,,hydro*loric ,,acid ,weight sample & tube #i4agic #h4agca #h4agca #f4iahg ------ ------ ,weight sample #a4jjfb #a4bedd ,f9al ,read+ ,h,cl #ci4ig #ci4hc #di4ij #di4gg ,initial ,read+ ,h,cl 4#jj 4#jj 4#jd 4#jd ----- ----- ----- ----- #ci4hc #di4gc ,f9al ,read+ ,na,o,h 4#bf 4#bf 4#fg 4#fg ,initial ,read+ ,na,o,h 4#ab 4#ab 4#cf 4#cf --- --- --- --- 4#ad 4#ca 4#ad 4#ca ,correct$ cc4 ,h,cl #ci4hc - ----- #ci4fh #di4gc - ----- #di4dj 4#ibhf 4#ibhf log sample #j4jjbe #j4jihc colog cc #h4djad - #aj #h4cjfc - #aj colog milli equival5t #a4bgeg #a4bgeg ------ ------ #i4fgif - #aj #i4fhjc - #aj ,normal value ,h,cl 4#dghb 4#dghi ,mean 4#dghf ,sign$ 6,page ,d6 ,date ,,det]m9ation ,,( ,,*lor9e ,,9 ,,*loride1 ,,sample ,no4 ,weight sample & tube #af4agba #ae4iigf #ae4iigf #ae4gaag ------- ------- ,weight sample 4#agde 4#bhei ,weight crucible precipitate #ad4ddif #ae4fiae ,con/ant weights #ad4ddhg #ae4fiae #ad4ddhe ,weight crucible #ad4bbaf #ae4caif ,con/ant weight #ad4bbaf #ae4caid ,weight ,ag,cl 4#bbfi 4#cgba log ,cl #a4edif #a4edif log weight ,ag,cl #i4ceeh - #aj #i4egjf - #aj log #ajj #b4jjjj #b4jjjj colog ,ag,cl #g4hdch - #aj #g4gdch - #aj colog sample #j4gehc #j4edch ------- ------- #a4ejge #a4ejgh ,cl 9 sample ,no4 #cb4ah #cb4bj ,sign$ ,,/r5g? ,,( ,,reag5ts ,! conc5trations giv5 9 ?is table are ^? sugge/$ = use 9 ! proc$ures describ$ 9 ! =ego+ pages4 ,x is obvi\s1 h[ev]1 t an exact adh]5ce to ^! quantities is n ess5tial4 ,approx4 ,approx4 ,grams relation relation p] to normal to molal lit]4 solution solution ,ammonium oxalate1 7,,nh#d7b;,c#b,o#d4;,h#b,o #dj #j4e,n #j4be ,b>ium *loride1 ,ba,cl#b4b;,h#b,o #be #j4b,n #j4a ,magnesium ammonium *loride 7( ,mg,cl#b7 #ga #a4e,n #j4ge ,m]curic *loride1 ,hg,cl#b #de #j4cc,n #j4ff ,potassium hydroxide1 ,,koh 7sp4 gr4 #a4bg7 #dhj ,potassium ?iocyanate1 ,,kscn #e #j4je,n #j4ee ,silv] nitrate1 ,ag,n,o#c #ba #j4abe,n #j4abe ,sodium hydroxide1 ,na,o,h #ajj #b4e,n #b4e ,sodium c>bonate4 ,na#b;,,co#c #aei #c,n #a4e ,sodium phosphate1 ,na#b;,,hpo#d4ab;,h#b,o #ij #j4e,n or #j4ge,n #j4be ,/ann\s *loride1 ,sn,cl#b1 made by saturat+ hydro*loric acid 7sp4 gr4 #a4b7 ) t91 dilut+ ) an equal volume ( wat]1 & add+ a slight excess ( acid f "t to "t4 ,a /rip ( metallic t9 is kept 9 ! bottle4 ,a solution ( ammonium molybdate is be/ prep>$ z foll[s3 ,/ir #ajj grams ( molybdic acid 7,mo,o#c7 into #djj cc4 ( cold1 di/ill$ wat]4 ,add #hj cc4 ( conc5trat$ ammonium hydroxide 7sp4 gr4 #j4ij74 ,filt]1 & p\r ! filtrate sl[ly1 ) con/ant /irr+1 into a mixture ( #djj cc4 conc5trat$ nitric acid 7sp4 gr4 #a4db7 & #fjj cc4 ( wat]4 ,add to ! mixture ab\t #j4je gram ( microcosmic salt4 ,filt]1 aft] all[+ ! :ole to /& = #bd h\rs4 ,! foll[+ data reg>d+ ! common acids & aque\s ammonia are bas$ ^u p]c5tages giv5 9 ! ,/&>d ,tables ( ! ,manufactur+ ,*emi/s' ,association ( ! ,unit$ ,/ates 6,j4,s4,c4,i461 #bd 7#aije71 #ghg-gij4 ,all gravities are tak5 at #ae4e;,c4 & comp>$ ) wat] at ! same temp]ature4 ,aque\s ammonia 7sp4 gr4 #j4if7 conta9s #i4ia p] c5t ,,nh#c by weight1 & corresponds to a #e4f ,n & #e4f molal solution4 ,aque\s ammonia 7sp4 gr4 #j4ij7 conta9s #bh4eb p] c5t ,,nh#c by weight1 & corresponds to a #e4f ,n & #e4f molal solution4 ,hydro*loric acid 7sp4 gr4 #a4ab7 conta9s #bc4ha p] c5t ,h,cl by weight1 & corresponds to a #g4c ,n & #g4c molal solution4 ,hydro*loric acid 7sp4 gr4 #a4bj7 conta9s #ci4hj p] c5t ,h,cl by weight1 & corresponds to a #ac4a ,n & #ac4a molal solution4 ,nitric acid 7sp4 gr4 #a4bj7 conta9s #cb4be p] c5t ,,hno#c by weight1 & corresponds to a #f4a ,n & #f4a molal solution3 ,nitric acid 7sp4 gr4 #a4db7 conta9s #fi4if p] c5t ,,hno#c by weight1 & corresponds to a #ae4h ,n & #ae4h molal solution4 ,sulphuric acid 7sp4 gr4 #a4hced7 conta9s #ic4ai p] c5t ,h#b,,s#d by weight1 & corresponds to a #cd4h ,n or #ag4d molal solution4 ,sulphuric acid 7sp4 gr4 #a4ah7 conta9s #bd4gd p] c5t ,h#b,,s#d by weight1 & corresponds to a #e4i ,n or #b4ie molal solution4 ,! t]m 6normal6 7,n71 z us$ above1 has ! same significance z 9 volumetric analyses4 ,! molal solution is assum$ to conta9 "o molecul> weight 9 grams 9 a lit] ( solution4 ,,d5sities ,,& ,,volumes ,,( ,,wat] ,,at ,,temp]atures ,,f #ae-cj;,c4 ,temp]ature ,d5sity4 ,volume4 ,c5tigrade4 #d #a4jjjjjj #a4jjjjjj #ae #j4iiiabf #a4jjjhgd #af #j4iihigj #a4jjajca #ag #j4iihhja #a4jjabjj #ah #j4iihfbb #a4jjachj #ai #j4iihdcb #a4jjaega #bj #j4iihbcj #a4jjaggc #ba #j4iihjai #a4jjaihe #bb #j4iiggig #a4jjbbjh #bc #j4iigefe #a4jjbdda #bd #j4iigcbc #a4jjbfhe #be #j4iigjga #a4jjbich #bf #j4iifhaj #a4jjcbja #bg #j4iifeci #a4jjcdgc #bh #j4iifbei #a4jjcgee #bi #j4iieiga #a4jjdjdf #cj #j4iiefgc #a4jjdcdf ,au?ority3 ,l&olt1 ,brn/e91 & ,mey]h(f]'s 6,tabell561 ?ird edition4 ,,corrections ,,= ,,*ange ,,( ,,temp]ature ,,( ,,/&>d ,,solutions ,! values bel[ are av]age values comput$ f data relat+ to a consid]able numb] ( solutions4 ,!y are suffici5tly accurate = use 9 *emical analyses1 except 9 ! comp>atively few cases :]e ! highe/ atta9able accuracy is dem&$ 9 *emical inve/igations4 ,! expansion coeffici5ts %\ld !n be c>efully det]m9$ = ! solutions employ$4 ,= a compilation ( ! exi/+ data1 consult ,l&olt1 ,brn/e91 & ,mey]h(f]'s 6,tabell561 ?ird edition4 ,corrections = #a cc4 ,conc5tration4 ( solution betwe5 #ae & #ce;,c4 ,normal 4#jjjbi #j4e ,normal 4#jjjbe #j4a ,normal or m dilute solutions 4#jjjbj ,! volume ( solution us$ %\ld be multipli$ by ! values giv51 & t product multipli$ by ! numb] ( degrees :i* ! temp]ature ( ! solution v>ies f ! /&>d temp]ature select$ = ! laboratory4 ,! total correction ?us f\nd is subtract$ f ! obs]v$ burette read+ if ! temp]ature is high] ?an ! /&>d1 or add$1 if x is l[]4 ,corrections are n usually necess>y = v>iations ( temp]ature ( #b;,c4 or less4 ,,int]national ,,atomic ,,weights #aibj #aibj ,alum9ium ,al #bg4a ,molybd5um ,mo #if4j ,antimony ,sb #abj4b ,neodymium ,nd #add4c ,argon ,a #ci4i ,neon ,ne #bj4b ,ars5ic ,z #gd4if ,nickel ,ni #eh4fh ,b>ium ,ba #acg4cg ,nitrog5 ,n #ad4jjh ,bismu? ,bi #bjh4j ,osmium ,os #aij4i ,boron ,b #aa4j ,oxyg5 ,o #af4jj ,brom9e ,br #gi4ib ,palladium ,pd #ajf4g ,cadmium ,cd #aab4dj ,phosphorus ,p #ca4jd ,caesium ,cs #acb4ha ,plat9um ,pt #aie4b ,calcium ,ca #dj4jg ,potassium ,k #ci4aj ,c>bon ,c #ab4jje ,praseodymium ,pr #adj4i ,c]ium ,ce #adj4be ,radium ,ra #bbf4j ,*lor9e ,cl #ce4df ,rhodium ,rh #ajb4i ,*romium ,cr #eb4j ,rubidium ,rb #he4de ,cobalt ,co #eh4ig ,ru!nium ,ru #aja4g ,columbium ,cb #ic4a ,sam>ium ,sm #aej4d ,copp] ,cu #fc4eg ,sc&ium ,sc #dd4a ,dysprosium ,dy #afb4e ,sel5ium ,se #gi4b ,erbium ,er #afg4g ,silicon ,si #bh4c ,europium ,eu #aeb4j ,silv] ,ag #ajg4hh ,fluor9e ,fl #ai4j ,sodium ,na #bc4jj ,gadol9ium ,gd #aeg4c ,/rontium ,sr #hg4fc ,gallium ,ga #fi4i ,sulphur ,s #cb4jf ,g]manium ,ge #gb4e ,tantalum ,ta #aha4e ,gluc9um ,gl #i4a ,tellurium ,te #abg4e ,gold ,au #aig4b ,t]bium ,tb #aei4b ,helium ,he #d4jj ,?allium ,tl #bjd4j ,hydrog5 ,h #a4jjh ,?orium ,? #bcb4d ,indium ,9 #aad4h ,?ulium ,tm #afh4e ,iod9e ,i #abf4ib ,t9 ,sn #aah4g ,iridium ,ir #aic4a ,titanium ,ti #dh4a ,iron ,fe #ee4hd ,tung/5 ,w #ahd4j ,krypton ,kr #hb4ib ,uranium ,u #bch4b ,lan?anum ,la #aci4j ,vanadium ,v #ea4j ,lead ,pb #bjg4b ,x5on ,xe #acj4b ,li?ium ,li #f4id ,ytt]bium ,yb #agc4e ,lutecium ,lu #age4j ,yttrium ,y #hh4g ,magnesium ,mg #bd4cb ,z9c ,zn #fe4cg ,manganese ,mn #ed4ic ,zirconium ,zr #ij4f ,m]cury ,hg #bjj4f ,,index ,acidimetry ,acid solutions1 normal /&>d ,acids1 def9ition ( ,acids1 weak1 action ( o!r acids on action ( salts on ,accuracy dem&$ ,alkalimetry ,alkali solutions1 normal /&>d ,alum9a1 det]m9ation ( 9 /ibnite ,ammonium nitrate1 acid ,analytical *emi/ry1 subdivisions ( ,antimony1 det]m9ation (1 9 /ibnite ,apatite1 analysis ( ,asbe/os filt]s ,atomic weights1 table ( ,balances1 ess5tial features ( use & c>e ( ,b>ium sulphate1 det]m9ation ( sulphur 9 ,bases1 def9ition ( ,bi*romate process = iron ,blea*+ p[d]1 analysis ( ,brass1 analysis ( ,burette1 description ( calibration ( clean+ ( read+ ( ,calcium1 det]m9ation (1 9 lime/one ,calibration1 def9ition ( ( burettes ( flasks ,c>bon dioxide1 det]m9ation (1 9 lime/one ,*lorimetry ,*lor9e1 gravimetric det]m9ation ( ,*rome iron ore1 analysis ( ,co91 det]m9ation ( silv] 9 ,colloidal solution ( precipitates ,colorimetric analyses1 def9ition ( ,copp]1 det]m9ation (1 9 brass det]m9ation ( 9 copp] ores ,crucibles1 use ( ,cry/all9e precipitates ,d5sities ( wat] ,deposition pot5tials ,desiccators ,direct me?ods ,dissociation1 degree ( ,economy ( "t ,electrolytic dissociation1 !ory ( ,electrolytic sep>ations1 pr9ciples ( ,end-po9t1 def9ition ( ,equilibrium1 *emical ,evaporation ( liquids ,f>aday's law ,feldsp>1 analysis ( ,f]r\s ammonium sulphate1 analysis ( ,filt]s1 fold+ ( h[ fitt$ ,filtrates1 te/+ ( ,filtration ,flasks1 graduation ( ,funnels ,fusions1 removal ( f crucibles ,g5]al directions = gravimetric analysis volumetric analysis ,goo* filt] ,gravimetric analysis1 def9ition ( ,hydro*loric acid1 /&>dization ( ,hydrolysis ,ignition ( precipitates ,indicators1 def9ition ( = acidimetry prep>ation ( ,indirect me?ods ,insoluble matt]1 det]m9ation ( 9 lime/one ,integrity ,iodimetry ,ions1 def9ition ( ,iron1 gravimetric det]m9ation ( volumetric det]m9ation ( ,jones r$uctor ,lead1 det]m9ation ( 9 brass ,lime/one1 analysis ( ,limonite1 det]m9ation ( iron 9 ,liquids1 evaporation ( transf] ( ,litmus ,log>i?ms ,magnesium1 det]m9ation ( ,mass action1 law ( ,measur+ in/rum5ts ,me?yl orange ,moi/ure1 det]m9ation ( 9 lime/one ,neutralization me?ods ,normal solutions1 acid & alkali oxidiz+ ag5ts r$uc+ ag5ts ,notebooks1 sample pages ( ,oxalic acid1 det]m9ation ( /r5g? ( ,oxidation processes ,oxidiz+ p[] ( pyrolusite ,p]manganate process = iron ,ph5olph?ale9 ,phosphoric anhydride1 det]m9ation ( ,pipette1 calibration ( description ( ,plat9um crucibles1 c>e ( ,precipitates1 colloidal cry/all9e ignition ( sep>ation f filt] wa%+ ( ,precipitation ,precipitation me?ods 7volumetric7 ,problems ,pyrolusite1 oxidiz+ p[] ( ,quantitative ,analyses1 subdivisions ( ,reag5ts1 /r5g? ( ,r$uc+ solution1 normal ,r$uctor1 ,jones ,rev]sible reactions ,silica1 det]m9ation (1 9 lime/one det]m9ation (1 9 silicates purification ( ,silicic acid1 dehydration ( ,silv]1 det]m9ation ( 9 co9 ,soda a%1 alkal9e /r5g? ( ,sodium *loride1 det]m9ation ( *lor9e 9 ,solubility product ,solution pressure ,solutions1 normal /&>d ,/&>dization1 def9ition ( ,/&>d solutions1 acidimetry & alkalimetry *lorimetry iodimetry oxidiz+ & r$uc+ ag5ts ?iocyanate ,/>* solutions ,/ibnite1 det]m9ation ( antimony 9 ,/irr+ rods ,/oi*iometry ,/r5g? ( reag5ts ,suction1 use ( ,sulphur1 det]m9ation ( 9 f]r\s ammonium sulphate 9 b>ium sulphate ,temp]ature1 corrections = ,te/+ ( wa%+s ,!ory ( electrolytic dissociation ,?iocyanate process = silv] ,titration1 def9ition ( ,transf] ( liquids ,volumetric analysis1 def9ition ( g5]al directions ,wa%-bottles ,wa%$ filt]s ,wa%+ ( precipitates ,wa%+s1 te/+ ( ,wat]1 ionization ( d5sities ( ,weights1 c>e ( ,zimm]mann-,re9h>dt me?od = iron ,z9c1 det]m9ation (1 9 brass