THE QUALITATIVE ANALYSIS OF GROUP I11 A Survey MARY MARGARET TENBUSCH and GEORGE E. F. BREWER Marygr-
College, Detroit, Michigan
F
OR the analysis of cations, so-called "dry methods" and "wet methods" are offered. Complete systems of analysis based either on chemical or on physical reactions are available in both the dry and wet technique. (See Bibliography, 1to 37). The exclusive use of some of these systems for elementary education in qualitative analysis is impractical because they offer little attraction from the educational point of view. This would be true, for instance, of the exclusive use .of physical methods since the typical chemical reactions of cations are not involved. The beginners in qualitative analysis, therefore, receive instruction mainly in chemical methods of analysis (i. e., the precipitation method) and since the ,instruction in analytical chemistry precedes the study of organic compounds, inorganic reagents are preferred. The increasing practical importance of some of the other techniques, however, makes i t highly desirable to familiarize the .students with at least a limited number of their applications, .esneciallv to 7). , snectrosco~ictechniaue (3 ~ ,. soot tests (8 to 121, and some of the special organic reagents (38 to 52). The systems qualitative precipitation .can be classified in two groups: those avoiding the use .of sulfide ion (14 to 251, and the almost universally -taught method of qualitative analysis, precipitation with sulfide ion. This latter system divides the cations into four or five precipitable groups and one soluhle group. The consecutive *precipitating agents for A
to whether or not they think that their particular method is superior to any other. Schematic tables of the methods given in the respective textbooks are presented below, while procedures used in the presence of interfering ions (i. e., PO&=,CzOr) have been avoided purposely. Compounds, complex salts, etc., are given as found in the denoted texts. We have included in this survey twelve textbodks (26 to 37) and have arranged the material in six main divisions according to the first step in the analysis of Group 111:
A. B. C. D. E. F.
A
these groups are HC1* H2S3and then either NH40H tolloWed by (NH4)zS,Or NH40H and HB used sirnub taneous1~9 and (NH4)2C03. The ions of the group are determined individual .only. Very little variation in the methods of qualitative determination of the HC1 and HzS group can be found, .or seems to be possible, but a variety of procedures to determine the ions of analytical Group I11 (Al+++, Cr+++, I++++, Co++, Ni++, Zn++, and Mn++) has been proposed. Generally colle offer only .one of these possible +his paper and its bibliography ,different methods available. ~h~ bibliography includ&s ~eferencesto the systems of qualitative determinations .of cations in general (1 to 37), qualitative analysis .of Group 111, and special reactions of the seven ions .of this group (38 to 82). we have undertaken to ask some of the authors of widely used textbooks about the special advantages .of the method outlined by them and have inquired as
CoS and NiS separated first. FeClaseparated with ether. A D - , ZnOn-, and Cr04-, separated first. ZnS precipitated from weakly acid solution. MnOaseparatedfmt. Precipitation with NH4OH in HnS-free solution, followed by precipitation of filtrate with (NHJnS.
A . cosand N ~ separatedfirst: S The fact that CoS and NiS are insoluble in dilute acids which dissolve the sulfides or bYdroxides of the other ions of G~~~~111 is mentioned by Muspratt (53), and an intensive study has been carried out by Thiel (54). The textbooks of Heisig (26), Meldrum (27), Treadwell-Hall (until 1936) (28), and Vosburgh (29) use this relative insolubility of CoS and Nis as the first Stepfor the qualitative separation of the ions of G~~~~III. .- Each of these authors, however, uses variations for the determination of the five remaining ions of the group. As a second step, for instance, Heisig and Meldrum separate Zn(NH3),++, whereas Treadwel]-Hall precipitate Fe+++, Cr+++,and Mn++ as hydroxides in an alkaline solution buffered by BaC03, and Vosburghprecipitates Fe+++, Al+++, and c r + + +in ammoniacal These procedures in the attached tables. are given G. B. HEISIG, "Semi-micro QualitativeAnalysis," w. B. Saunders Company, New York, 1943: . The chief merit of the analytical procedures used to separate and to identify the cations of Group 111, used in my book, is that they work well in the hands of beginning students. BYseparating the rest of the cations from the zinc ion at the beginning of the analysis of the group, the student is not as apt to lose the zinc as the 0 t h cations ~ of the group are successively precipitated from the solution containing the zinc ions. The oxidation of the manganous ion by a solution of sodium bromate in sulfuric acid works well and replaces the use of a boiling mixture of concentrated nitric acid and sodium or potassium chlorate. G. B. HEISIG
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Umvaasr~uor M~NNBSOZA
CoS. NiS, ZnS, MnS, FeS, AI(OH)r, Cr(OH)% precipitated. Add 1 N HCI. Boil05 H.S. Add HNOz, boil. Make alkaline with NHI. Add (NH.)sCOI Prcripilola: CoS, NiS. Dia- Solulion: Znii, Mn*+, Fe*', Altt', Crft'. A * = . . solve in conc. HCI and cane. HNOI. Filter and boil. Fili~ole:Zn(Nffi)~*' PrcriPilolc: MnCO*, Fe(OH)r, AI(0H)r. Cr(0H)s. Dissolve in thc minimum amount 01 HCI. Neutralize with NH.OH. Acidify with HAe. Make alkaline with NaOH, add HIOX. Heat. Filter. Add H,S to form ~reci9itotr: MnO(OHh, Fe(OH)r. Add Solxtion: AI(OH)A-, trod-. ~ d HdN O ~then , NH,, Tert m e part with dimethyl ZnS, in HsSO', heat. filter. Add NaBrOa. Boil. until alkaline. g l ~ o r i m efor Nii+. HCI. PrcriPilolc: MnO(0- I Solulion: Fei++. I Pmci+ilola: AI(0Hh. I Fillralc: CrOr. Add H ) ~M , ~ O X . con~ d NHI. d a&m by do-aiuNH'AC, =Ac, and Tert another part with NHIfirmby NarC0z.K PrcciPilolc: Fe(0H). minate tert or aluPbAe,. SCN for a++. CIOI, or by osdaminon test. PmVilola: PbCrO,.
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+"
+in*
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W. B. MELDRUM, E. W. FLOSDORP, AND A. F. D a o o s n , "Semimicro Quditative Analysis," American Book Company, New York, 1939: . . At present a =evised procedure for Group 111 is in the process of being tested. The principal trouble experienced in our earlier Group 111procedure (represented below) arose from the use of cold 1 N HCI for the separation.of CoS and NiS from the
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F. P. TEEADWELL AND W. T. HALL, "Analytical Chemistry: Qualitative Analysis," John Wiley and Sons, Inc., New York, 1903: . . . Prior to 1914, we used the BaCO* method a t the Massa-
other members of the group. An imperfect separation usually caused an interference with the confirmatory tent for zinc. While our revised procedure eliminates this difficulty entirely, since it is still in the testing stage, I prefer to make no definite Statements regarding it a t present. . . . A. F. DAGGETT UNNBRSITY
OP NBW HAMSHIRE
chusetts Institute of Technology but I don't believe any of us would go back t o it. W. T. HALL
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M b s s ~ c w s s r r INSTITUTE s OR
T~~~NOLOOY
CoS, NIS, ZnS, MnS. AI(OH)r, FeS. Cr(0H)r. n e a t ~ i t 2h N HCI. id"^: cos and NIS. iss solve in Sowion: z n t + . ~ n + +A, l t + + Fe++, Crt++. Boil HtS 05. Add Bn-water, boil excess ~s05. neutralize, and add BaCOl rurpenrion. HNO-HCI. Evaporate t o dryness. Divide. Solulion: Zni+, Mni+. Bait. Add Rmiduc: AI(OH)s, Fe(OH)a, Cr(0H)i; BaCO,. Diaolve in HCI, &SOa, boil, filter. Add exeessofNaOH. add H2S0.,,filter Bas01 off. Divide: CoCh. R E S ~ ~ Y I : CoCIs, Rcridvc: M C h . Dissolve Solulion: ZnOl++. Residua: Mn(OH)s. Solution: NiCL. Dimllve Ali++. Solution: A]+*+ F e w * C r t + + . Add an i n H30t KCN. inKN01soIution. DissolveinHCI. F e t t t , Cr+++. excws of KOX. ~ d KMnOa. d Boil. ~cidifywithHAe NaOH. Add C1, filter, acidify with HISO., decolorize ~ i t h ~ d &s, d Neutralize with Add &Fe(CNh. Prcripilola: K~COgar. NHt. add KCN. Pre~iPiIal~: PNJPrcciPilnC: ZnS. CzHsOK. Make alkaline with NHZ. Prccigilnk (black): (N041. sian Blue. (NEW. Residuc: AI(OH).. Solution: CrO.: NI(OH)I. Pvedp~lole(pink): Identifv as blue
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W. C. Vossuncn, "Introductory QualitativePAnalysis," The ,, Macmillan Company. New York, 1938: . The method of analysis of Group I11 in my book is the method devised by Sneed, Heisig, and Trovatten and published Vol. 5, page 87 (1928). in the JOURNAL OF C m m m EDUCATION, with some minor variations. The originators of the method discuss its advantages. One impartant improvement, I believe, is the use of bromine rather than nitric acid t o oxidize iron. Excess nitric acid introduced a t that point may lead t o a precipitate of sulfur in the Jkal test for zinc, while excess bromine can he removed by boiling. Another important improvement b the slow precipitation of the hydroxides to avoid t carrying down of
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divdent metal ions that should remain in solution. I selected this method for my hook because it seemed simpler and better adapted t o the needs of beginning students than the Noyes procedure. When the objective is t o teach chemistry, a more complicated procedure capable of giving fine analytical results mav be less desirable than a nrocedure the students ~~- can understand and follow correctly without tao much practice. Materials for ar~algsiscan be adjusted t o thc procedure. For the same reason I do not like organic reagents; most of my students have not studied organic chemistry . w. C. Vossunox ~
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DO==UNI'IBRS~TY
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B. Feels sefiarated with ether: The fact that F e + + + can bequantitatively extracted from 6 N HCl by ether is utilized by Swift(30) ~ ~ ~ ~(31). ~ s .w i f t~ goes ~ on to precipitate the suEdes of Zn++, Co++, and Ni++ by Has f r o m a solution containing ammonium oxalate and sodium bicarbonate, whereas Noyes-Swift separate MnOa as the next step (KCIOa-HN03)and from there on followthe N~~~~method (32) for the separation of the insoluble Ni(OH)z and C o x 0 3 f r o m AlOz-, CrO4-, and ZnOp- ions which form in very strong alkaline solutions. Evaporate. Add HCI, KI. Titrate with Na,SrOl. Compute Fe+ *.
E. H.Swmr, "A System of Chemical Analysis." Prentice-Hall. In"., York, lgS9: MY interest was in the development of a system of analysis i f t which would give much more quantitative separations than those provided in conventional systems. Therefore there was justification for using procedures which are not as simple as the more conventional ones. This would apply especially t o the ether separation of iron, the separation of the zinc and aluminum groups, the nickel and cobalt separation, methods which are t o be used only when the elements involved are present in substantial amounts and quantitative infomation desired, ,
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Plcripilok: ZnS. CoS, NiS. Dissolve in HCI-HNOs, fume with conc. HsSO., dilute, neutralize with .NaOH, add dil.
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u.sn, --.,u..* PreciPilal~: ZnS.
Add t o Fq(SO3r heat. A d d H 6 0 1 (precipitate: S). Solution: Zn*' and Fe++. Titrate Pet+ with KMnO*. Campute zni+.
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Fillrolc: Ai(C103r---, Cr(G03--; M n ( G O d r . Acidify with HNOI, heat, evaporate, a d d HNOI, evaporate, add HNO,, amn, . -. , ha.+ . Solulion: N i t + . Cot+. Boil, add excess PrrciWole: MnO,. SoluIion: Al+t+, Cr,Oc. Nmtralire NaOH [precipitate: Ni(OH)r.Co(OH)~]. Dirsolve in HCi, with NHIOH. Add excess Nar02. Dissolve [precipiKi. Titrate with Prrci~ilnlcAI(OH)~Solution: CrO, C. Solulion: Pet++ Sollion: Add &Fe(CN)#. Bluc prrcipirole FedIFe(CN)+.
A. A. NOYES,"Qualitative Chemical Analysis," The MacmiUan Company, New York, 1932: .A. A. Noyes had an ideal of getting out a scheme of analysis which would serve t o detect one m i K i a m of an element in the presence of 500 milligrams of any other. Noyes and his students worked on the scheme, which was meant t o include all elements, for 30 years and regarded it as the best thing he ever did. I had Noyes as a teacher in 1894-95 and he was one of the mast inspiring teachers I ever had. W. T . HALL
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MASSACBDSBTTS INS-TB
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TBEBNOLOOY
S, NiS. Dissotye in HCI. KCIOI, add NaOH. 8H)s. NKOH),. Zb(OH),. Treat with HNOz. KCIOI. Solution: AIO2-. ZnOr. Crop. Atidify lnith HCI, add NH6OH. :,I*+, Cot+. Ni". Divide: P'L~iPilolC Al- Fillmlc: Zn(N&)dt+, CrO--. Add Solution: Add NH'OH, H a . Prrcipifolc: ZnS, CoS, (0H)r. Dissolve N ~ C O I boil. , NiS. Treat with 1N HCI. in HNO'. Add Prcci+ilata: Zn- Pil~rotc: cr04: .yalution; z n * * ficcigildc a s , N~S. ~ d HCI, d (OH).. DisAdd AAc and - (smallamount KCIOt. Evaporate, add HA", ) solve in HCI. PbAo. Cof *. of KNO,. Add NH'OH. Prccipilolr: Nit+>. Add P I C C ~ P ~ K IO I -I ~ ;s o i ~ t i o % ~ : i + + . CO(AIOI)I. rcriduc (NHM. PbCrO'. NaOH, Na202 Co(N038. Test with diP r c c i ~ i l o l c z n s . Add ( N H h S . methylglyoxWhilc p m i 9 i ime for Nit+. 1atr: z n s .
F. P. TREADWELL AND W. T. HALL,"Anilytical Chemistry: Qualitative Analysis," J. Wiley and Sons, Inc.. New York
that was based on more careful work. I have been astonished t o see so few objections raised to it.
1937:
. . . Noyes' procedure is good and I have never seen another
J. H. REEDY, "Elementary Qualitative Analysis." 3rd Ed.. McGraw-Hill Book Company, New York, 1941: c r ( 0 H ) is ~ the real mischief maker. This substance carries down in its precipitation Zn*+, and particularly the ions of the alkaline earths and magnesium. This may be a matter of simple copredpitation, but most authorities prefer t o think that insoluble chromites are formed. This means that when Cr+++ is present in quantity, Znt+, Ba++,etc., may be wholly removed from the solution. This would cause not only failure t o detect these ions in their proper places in subsequent. groups, but their presence in the Al+++, Crtt+, Fe+++group might lead tocomplications. Another objection t o the separation of tri- and divalent ions by selective precipitation of their hydroxides with OH- is that
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W. T . HALL M A S ~ A C ~ S E T TISN S ~ ~ U Top B T
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iron must becompletely in the form of Fe+++to he thrown down. Students frequently have trouble in the complete oxidation of Fe. The favoxite procedure a t this time involves the oxidation of Cr+++ to Cr04- in alkaline medium, and then the separation of the combined groups on the basis of their amphoterism. That is, AIC++, GO,-, and Zn++ would remain in solution as A1OZ-, Cr04-, and HZnOa-, while the rest of the ions of the combined group would be precipitated as hydroxides (or hydrated oxides). I n my opinion the latter method is preferable t o precipitation of hydroxides from graduated concentrations of OH- ions, especially when chromium is present.
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J. H.
REEDY
U ~ r v s a s l r 03 y IL'.NO.S
AI(OH)I, Cr(OH),. ZnS. MnS. FeS. NiS, CaS. Dis~olveIn HCI, RNO.. boiling. Filter off S, add NaOH. Na3Ol and NasCOz. Filtmlc: NaAIO,, N a O O l , NpuZnOz. Add dil. HCI, Eaeess of Prrcipirnlr MnO*, Pe(OH)a, Ni(OH)a, Co(0H)s. Add mnc. HNOl. boil. Add N ~ N O ~ , solid KCIOI. Filter on asbestos. NH4OH. MnO.. Prccipilofo AI(OHh. Solullon: Na.CrO4, Zn(NHaht+. Boil. Rcriduc: Fiilrolc F e t + + , Ni++, Cot+. Add N H 4 0 H in uceSr. Add PbO*. dil. prEcip;lorr:pe(~~),. divide. Test smaller portion with HBiO.. Diooolvc N;(N&),++, co (NHzII)I++. HaO,, ether. HsOe for. Cri++. HNOI, boil. in hot HCI. add Dissolve in HCl. Divide: soiution: pw1e aluminon. neutnl- TO second portion B~AC~. Confirm with Acidify wifh.HAE.. Acidify with cone. HMnO,. ire with NHdOH. SCN- and %Iao Add dimethylHCI. Add NHc to boiling: Pred$itdc: BaCrO,. Solufion: Saturate with &Fe(CN)r. filtrate with H S . glyorime. SCN, amyl almhol AI-lake. While p r ~ ~ i a i l a l ~ Red OrccNifofc: ether. shake. R I , , ~ . zns. ~i-di&!&glygreen layer iodi.
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D. ZnS precipitated from weakly acid solution: This group of methods makes use of the fact the Zn" is the only ion of Group I11 which can be precipi fide from acidic (see 'lso Taylor, p a t F, o f this survey). Meldrum and Dagvett use monochloracetic acid-ammonium monochloracetate as buffer for the precipitation o f zinc sulfide in the presence of any or all the other ions of G~~~~111. Hogness and Johnson (35) dissolve the s u m e s or hydroxides of Al+++, Cr+++, Fe+++, and Mn++ by the use of the weakest acid (NaHS04-Na&Od). leaving . . the undissolved sulfides of do++, Ni++, a n d i n + + as residue. Later Zn++ is precipitated as sulfide from the
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weakest acid solution, buffered by . NaHS04-NaES04. , w. B. MELDRUM AND A. P,DAGGBTT:
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I have now the results, obtained by students a t Haverford College and also here a t the University of New Hampshire, ming our revised Group 111procedure; I am taking the liberty of enclosing .a CODY .. of it for youi use. The results obtained using the new procedure appear t o be very satisfactory. The difficulty experienced with our original procedure, of the interference of nickel and cobalt with the conh a t o r ytest for zinc, has now been eliminated. This re+ised pracedure will appear in our new book t o de published during the coming year (1946). A. F. DAGGETI
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0 1 Naw
H-ssnras
~ d NHCI, d I5 M NHdOH in excess. Heat. Saturate with H a . Centrifuge. Add 15 M NH4OH and saturate with HIS again. Wnsh. Add 12 M HCI, 16 M HNOI. Heat. Add 15 M NHaOH, 4 M monachlora~dicacid. Heat. Add HzS. Prcrigilola: whiteor Solution: Coi*. Niit. Ali**. Cri++. Mr.+*, Fet*. Boil to remove HtS. Add Bn-water. 15 MNHaOH. 3 M (NH4),C08. g f w preeipifafe. ~ , ~ ~ i p i ~Mo ~l ~ : F. ~ + + AI+*+, ++ +, cr+**. ~ d IdS M NH~OH,1 2 M HCI. NaOH, Solution: c o + + , ~ i + + .~ d CHICOOH. d ZmC. Confirm by 3% H a . Heat. Divide. adding Soiulion: C r + + + .AL+++. Boil. Add HNOa. Add dimethyl gly- Add ~r-nitroso.8 Warm. If predpi- Prcripifolc: Mn*+, F e + + * . Add HNOl 15 M NHaOH. orime and N& naphtholrolufion. tete dirrolven. OH. Praripilnlc: Cot+. .jne confirmed. Prccipilolc: indi- Solulion: Fe++*. PrccMilolc: AI(0H)r. Solution: Cri++. Pmiwa*: Ni-di- ~ A~~CHICOOH, eates M ~ + + . A ~ ~ N H . O H . H - D ~ S W I V ~in HCI. ~ test: ~ ~ d td methyl d ~ o r i m e . Add NILAe. FbAea. CI, &Fe (CNl8. Add HNOI. 3% KNO,. warm, sluminon, NH.OH, Prlcipifnl~: Pb-01, HNOI. Precipilotr: FaPrrcipilalr: KI(NH.)sCOn. Heat. CrO.. ColNO2)a.
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T. R. HOGNES AND W. C. JOHNSON, "Qualitative Analysis and Chemical Equilibrium," Henry Halt and Company, New Ybrk, 1940: . . . I t is of advantage t o identify the zinc h t , since the usual difficulty in the determination of zinc, i.e., coprecipitation with chromium and manganese, is avoided. T, R,H~~~~~~
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UNIVBESITY 01.C
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. . . Dr. Hogness and I have never been particularly impressed by the need for a perfect analytical procedure of the type commonly used in the teaching of qualitative analysis. There are many reasons for making such a statement. One is that when a student gets into industrial work or into research of any type, he will never use these procedures for analytical purposes excepting in a general way as they apply t o the separation of groups of elements. The new procedures-such as spectrographic, colorimetric, spectrophotometric, and highly specialized precipitation
procedures-which have been developed during the past twenty years, are so much more rapid, accurate, and practical. The important function of teaching qualitative analysis as we do is t o teach the student the chemistry of the ions and t o give him a working basis for the application of the Law of Mass Action. The analytical procedure is merely an excellent medium for accomplishing these two aims. A third aim is the development of techniques, especially those employed in the semimicro scale, in handling solutions and separating the different components from each other. While i t would be nice t o have a perfect scheme, i t appears to us that this is of secondary importance. As a result I would be more inclined t o place in a qualitative analysis procedure as many elements as possible consistent with the teaching of the chemistry of different types of ions and with ease of separation of the ions. WARRENC. JOHNSON
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Um-rnarrru os Ctlrcnco
E. Mn09 sebarated first: Advantaee can be taken L. I . C m r a a n ~ ,"Semimicro Qualitative Analysis," The MacNew York, 1942: of the fact that MnOz ;s only slightl;soluble, and an . . . It is well known by laboratory workers in the analytical iqn++ in early attempttp use this factby field that in the analysis of the Group I11 cations, manganese is gas was made Schiel. and a troublesome element. It occurred t o me that if 1could remove NaAc is called "ingenious" by Muspratt [(53) Val. 2, P. 5441. it a t the outset of the analysis by precipitation with KCIOn in However. the a~nlicationof chlorine gas is cumbersome HNOs solution, I would be able to simplify the analysis. Experiso Curtman (34) has proposed oxida. ment showed that this could be done. This procedure has the and advantage of simultaneously midizing Cri++ t o tion by ~ ~ to obtain 1 0M ~~ as O ~ firststep in his further at' the beginning of the analysis,. thus supplying an additional text. In the next step F 4 W a and -WOH)a are pre- .-.in t~ h- .~ ~~ ---OF nrorcdnrc. - - - - -- . .. . cipitated while Cr04- and the ammonia complexes . . .The separation of Nif + and Co++ from Zn++ by means of NaOH apd Na,Os, if properly carried out, is very satisfactory. of Co++. Ni++. and Zn++ remain in solution. F i n d , the Zn++ is precipitated by H2Sin the NaOH filtrate. then 'be identified as B ~ c & while ~ the cro4A white recipitate must be Znt+, since any undecomposed perthe of the remaining ions, Ni++, and oxide 1 t in the solution does not Oxidize the Hfi to S Zn++, is carried out simply by precipitation of Co- solution is alkaline. a fact bv manv .. . exoeriments. . (OH)a and Ni(OH)2 with strong alkgi which keeps L. 1. CURTMAN ZnOz- in solution. T==COLLBOB on =mB CITY on NBW YORK .a
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simnliecatiOn ~~
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Al(OH)r. Cr(OH).. FeS, NiS, CoS, MnS. ZnS. Dissolve in HCI-ANOr, evaporate. Add KCLO,, heat, ecntrifugc. M&,. Con6rm Solulion: Alt++, CnOl: P e t + + , Ni++. Co++, 'Cot+. Remove ermsr HNOI by evaporation. Add NHINO, and NAz. Centrifuge. with Na.COa, KC103 b u d , or ConvFCt to Rssidur: Fe(OH),, AI(OH)r. Add ex- Sohrion: CrOT, Ni(NHdnt+. Co(NH&++, Zn(NIPdr+*. Add BaCI.. MnOd-. cess NaOH. C m M u g e . Solulian: Ni(N&)nti, Co(NHl)a++, Zn(NHdait. Add HIS R d d u r : BaCrOd. and discard solution. Dissolve NiS. CoS. and ZnS in HNOI. AlRariduc: Pe(0H)i. Solulion: Add NaOH, NaxOl. Centrifuge. (OH),-. Rcriduc: Ni(OH)., CO(OH)I. Dissolve Soluion: Z n ( 0 H ) P Treat with H2S. in HCI, neutralize with NaOH. Precipilolc ZnS. acidify with HA=. Divide. Test for Niti. I Test for Cat+.
F. Precipitation with NH40H in H2S-free solution followed by precipitation of filtrate with (NH4)z.S: I n this way Group I11 is divided into two independent groups: the iron group and the nickel group. Six analytical groups result in this way-Group I: Ag+, Hgz++, Ph++; Group 11: the eight usual ions; Group 111: Al+++, Cr+++, Fe+++; Group IV: Co++, Ni++, Zn++, Mn++ (or Mn++ may be placed in Group 111); Group V: Ca++, Ba++, Sr++; Group VI: alkali
metals. This method is used in the textbooks of Kelsey and Dietrich (36) and of Barber and Taylor (37). According to both methods, the iron has to be oxidized to the trivalent form. Whereas Kelsey and Dietrich use concentrated HNOa as an oxidizing agent, Barber and Taylor use Brp-water in ammoniacal solution. This brings about a minor variation between the two methods; only the iron is oxidized by HNOl while manganese is left in the divalent (soluble) form. Kelsey
and Dietrich treat Fe+++,Al+++, and C r + + + as one group; however, since manganese is oxidized by Brawater to the trivalent form, it is precipitated together with Fe+++, Al+++, and Cr++ions in theBarher-Taylor system. The f u r t h e r analysis of the iron group makes use of the f o r m a t i o n of AIOa- and Crop, which stay i n solution while F e ( O H ) & [in Barber and T a y l o r ' s book, F e ( O H ) 3 and Mn(0H)J is precipitated. The two texts differ also regarding the Ni++ group. Kelsey and Dietrich convert Co++, Ni++, Mn++, and Z n + + i n t o sulfides and separate the insoluble CoS and NiS (2 M HCl) f r o m Mn++ and Z n + + ; Barber and Taylor precipitate Z n S in H A c solution the pH of which d o e s not allow the precipitation of Ni++ or Co++. ,-,
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E. B. KELSEYAND H. G. DIETRICH,"Fundamentals of Semimicro Qualitative Analysis," The Macmillan Company. New York. 1940: . There are two closely associated reasons why the authors of "Semimicro Qualitative Analysis" chose t o separate the cations of Grouo 111 as we do. T h e text is de5ignr.d for one tenn courses in analysis. The chief emphasis is on principles of analysis rather than on a detailed study of analytical reactions. l'hcse principles seem to be brought out better by the use of two separate groups than by combining the ions into a single group. If the seven cations involved are considered in a group, we feel that the student tends t o become confused with details of procedure and learns less of the actual principles involved. Experience bears out these views. E. B. K E L ~ E Y
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UNIVERSITY
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Add cone. HNO., heat, dilute, add N&CI. Make alkaline with NHaOH, filter, wmh. Pmcipilolc: (Iron Group) Fe(OH)r, AI(OH)r, Cr(0H)r. Add Solulion: (Nickel Group) Cot+. Ni'+. Mnit. Znti. Pass H 9 into solution. filter. neat precmitafe with A4 RCI. NaOH. H%O,,stir, heat. Sal~lia)cM n + t Zni+. Evaporate, make Rcriduc: CoS, NiS. Divide: Reridur: Fe(OH),. Sollion: AIOI; C r O r Add slid N& CI. confirm prec =en with ~cridur: ~ i r ~ t v e ahline with NaOH. filter. ~c~iduc: a c e of Pet++. Prccip;lofr:A1(OH)~. Solution: Pr~cipilolc:Mn(OH)~.Salufion: Zn0:-. in aqva re& Borax bead for CrOr. Disrolve in HNOa, AridifrwithHAe. Ewpornte. D i r Disrolve in HCI, AeidifywithAAc. . Cot+.
I
I
H. H. BARKERAND T. I. TAYLOR,"Semimicro Qualitative Analysis," Hamer Brothers, New York, 1942: .The Group 111may be separated into one group ides, q d then into another group as sulfides. ~h~ latter method is followed in the Barber-Taylor text, for the following reasons: conI n semimicro oualitative analvsis, the volume is seouentlv the filtrate from Groud11 &av easilv and auicklv -~ . . have the hydrogen sulfide removed by boiling. The filtrate is now a n acid solution without hydrugcn sulfirlr. Ry the addition of am-
..
~
.~ ~.
I
monium hydroxideand bromine water the hydroxidesof aluminum and chromium (Cr+++)will be precipitated, and the ferrous ions will be oxidized t o ferric ions, and the latter will be precipitated a s ferric hydroxide; the Mns+ will be oxidized t o Mn+++ and will be precipitated as Mn(0Hh or maybe MnO(OH)r, while the zinc, cobalt, and nickel ions will form ammonia complexes and remain in .
.
~
~ : w ~ v ~ a sOF~ ~r IuI U K P S U T A
i
Al+++,Cr'++,Fet+,Mn++, C0++,Ni++, zn+*. ., Add NH4CI. NHaOR, heat, add Brrwatcr. Pndpilate: (Iron Gmnp) AI(0H)a. Cr(0H)r. Fe(OH)s, Mn(0H)r. Add NaOH. Soldion: (Nickel Group) Ca+*. Nit+, Znt*. Boil, add HA= saturate wrth &S. &Ox, boil. ZnS. Piitrole: Nit+. Cot+. Add NHIOX solurian: A n - . CrOr, ZnW. Di- Rcriduc: Fe(0H)r.Mn(0H)s. AddHNOl Prrcipilola: Confirm if neeesand hydroxylamine hydrochloride (or ' (NHdS. ~ide.If solution yellow, test for Znt+. saw. Dissolve in ~ ~ ~ ~ i p iNi~ ~ Ha%), ~ : S , i soiulion: ~~t~~ idif if^ ~ i t hHA". ~eidifywith HAC. HCI. Boil. add COS. ~ d ,d~ a - groups. ~ d EdF ~ ( C N ) ,or Add NaBiOa. ~ d d aluminon Add PbAa NHAc and 8-hyCIO, HCI. B ~ ~ I . ~ ~ . S C to N deP ~ ~ ~ ~ c M~o.-. o I o ~ : ~~ccipiiotc:~bcro.. and (NH.)ICOZ. droryquinolioe. Divide: termine presence PrccUilolr: Al-lakc. Test for Ni with diof Pe++,.. methylglyoximc. and for ca with
nifmro-R-salt.
LITERATURE CITED A.
Dry Methods: (1) TREADWELL, F. P., "Analytische Chemie," Vol. I , Franz Deuticke, Leipzig,.1927, p. 431. 12) Trr~z.0 Z . anal. Chem.. 47. 1 (1908). . - .. B. Optical methods: (3) . . KAYSER,H., "Handbuch der Spectroscopic," S. Hirzel, Leipzig, 1901-12. (4) BRODE,W. R.. "Chemical Spectroscopy," John Wilev and Sans. Inc.. New York, 1939. (5) GBRLACH,W.. KT u . , " D i e chemkche EmissionsSpektralanalyse," Voss, 1929, 1933, 1936. (6) SCHEIBE,G., "Spektroskopische und radiornetrische Analyse," Akad. Verlagsgesellschaft, Leipzig, 1933. (7) SMITH,D. M., "Metallurgical Analysis by the Spectrograph," Metals Research Association (Brit.) Monograph 2, 1933. C. Wet methods: 1. Spot tests: \-,
.-
. . .
FEIDL, F., "Spot Tests," Translated by J. W. Matthews, Nordemann Publishing Company, New York, 1937. FEEL, F.,AND H. A. SUTRR,Chemist-Analyst, 32, 4-6 (1943). Z , H. HAMBURG. FEIOL, F., P. K ~ U ~ W O LAND Z . anal. Chem., 90, 199-202 (1932). FBIGL,F., AND H. J. KAPULITAS, Z. a n d . Chem., 82, 417-25 (1930). . TANANAEV, N. A,, Z. anorg. allgem. Chem., 140, 320-34 (1924). 2. ~olarographictechnique: (13) MUELLER, H.. "Polarographic Method of Analysxs, J. CHEM. EDUC.,Easton, Pennsylvania, 1945. 3. Precipitation (without H2S): (14) CI~AO, T. P., AND S. C. HWANO, J. Chinese Chem. Soc., 8, 21-31 (1941). (15) ZELADA, F., Anales asoc. puim. argentina. 30, 29 (1942). ~, (16) KHOROSHKIN, M. N., Acfa Univ. Voronegiensis, 10, 95-102 (1939).
-
,?.
SHCHIGOL,M. B., AND M. DWINSKII, Ann. chim. anal. chim. appl., 18,25742 (1936). LEWIN, A. B., Z . awl. Chem., 105, 328-31 ,,nor\ ('i..,",.
GERSTRNWNG, E. M., J. CHEM. EDUC., 11,
-"" .- ,-" --,. ?fiL7? f l Q?A>
KOMAROVSKII. A. S.. AND V. I. GOREMUIRIN, J. Applied Chem. 4, 877-80 (1931). PAMFIL, G. P., Mon. sci., 24,64143 (1910). TRAPP,H., 2. e n d . Chem., 51,475 (1912). h m c o r r r , A., Gazz. chim. ital., 42, 11, 58-67 11911). ALMKVIST. G., 2. anorg. allgm. Chem., 103, 22149 (1918). DoeBINs, J. T., AND E. S. GIL.REATIX. J. CHEM. EDUC.,22, 119 (1945). 4. Precipitation (withH8): (26) HE!sI~, G. B., "Semi-micro Qualitative Analysls, W. B. Saunders Company, New York. 1943. MELDRUM, W. B.. E. W. FLOSDOR*.. AND A. F. DAGGETT, "Semi-micro Qualitative Analysis." American Book Company, New York. 1939. TREADWELL. F. P., AND W. T. HALL,"Analytical Chemistry: Qualitative Analysis," John Wiley and Sons, Inc., New York. 1903,1937. VO~BURGH, W. C., "Introductory Qualitative Analysis," Macmillan Company, New York, 1938. SWIFT.E. H.. "A Svstem of Chemical Analvsis." - . renti ice-&I, I&., New York, 1939. NOYES,A. A., AND E. H. SWIFT,"Qualitative Chemical Analysis." Macmillan Company, New York. 1942. NOYES.A. A:. "Qualitative Chemical Analvsis." . . Mamillan Company, New York, 1942. REEDY,J. H., "Elementary Qualitative Analysis." 3rd Ed., McGraw-Hill Baok Company. New York. 1941. CURTMAN, L: J.. "Semimicro Qualitative Analysis," Marmillan Company, ~hrcwYork, 1942, H o c ~ s s s1'. , It., AS" \V. C. JOHNSOS, "Qualirativc Analvsis and Chemieal Eouilib"um." . kork. 1940. Henry it and C a ~ a n v New KELSEY,E: B.. AND H.-G. ~D~ETRICH, "Fundamentals of Semimicro Qualitative Analysis," MaCmillan Comoanv. New York. 1940. BARBER, H. H., A ~ ; D?.'I. T ~ ~ ~ & , " % & n i c r o Qualitative Analysis," Harper and Brothers, New York, 1942. I I . 'Special References to Group III: A. Oraanic Reaaents: Rossr, L., AND R. G. CORNATO, Rew. ~ S S O C .biaguim., argentina, 7, 11-20 (1941). KOENIG,E. W., Chemist-Anaest, 30, 15 (1941). Rossr, L., AND A. TRONCOSO, Reu. essoc. biopuim. argenlina, 4, 11-24 (1939). R o s s ~ L.. , C. A. LANARO, AND I. LUSIN,ibid.., 3, Fr6 (1938). LEHRMAN, L., H. WEISBERG, AND E. A. KABAT, 3. Am. Chem. Soc , 56, 183638 (1934). BELOUSOU, A. M., AND A. G. BELOUSOVA. J. Applied Chm., 7, 837-8 (1934). FUNK, H., AND M. D I ~ Z, . anal. Chem., 91, 33240 (1933). SHEINKMAN, A,, ibid.. 83, 17688 (1931). Yu, T. L., Science (China),14,810-20 (1930). GEOSSMANN, H., B. SCHUCR,AND W. HEILBORN,Bull. soc. ind. Rouen, 38, 116-127 (iqin1 - - - ,. (48) SANCHEZ, J. A,. Bull. SOC. chim., 9,880-1. \
(49) . . WENGER.P.. R. DUCKERT.AND D. RIETH.Helv. Chim. A&, 25, 406-15 '(1942). (50) BRYANT.W. M. D., J. MITCHELL,JR., D. M. SMITH, AND E. C. ASHBY,J. Am. Chem. Soc.. 63, 2924-7 (1941). (51) BLICK. D. J., Rept. New Engl. Assoc. C h m . Teachers, 43, No. 1, 13-19 (1941). (52) YOE, J. H., AND L. A. SARVER,"Organic Analytical Reagents." John Wiley and Sons, Inc., New York. 1941, pp. 263-326. Nickel Ion: (53) MUSPRAIT,J. S., Vol. 11, Glasgpw, 1860, p. 591. Quotes Llehtg on separatton of cobalt L . . .t
"L.7~~1 ".L=.C..
AND
\
- - -41 -,.
GESSNER,2. anorg. Chem., 86, 1
(55) TSCHWGAEPP, L., Ber., 38,2520 (1905). (56) BRuNcK, 0.. Zeit. angew. Chem., 20,1844 (1907) ; ibid.. 27, 315 (1914). (57) FEIGL,F., Ber., 57B, 759 (1924). Z, 7. (58) HELLER,K., AND P. K R ~ O L Mikrochemie, 213 (19291. . Cobalt Ion: (59) VOGE (60) TREA 26, 105 (1901). T . T., Z. a w l . Chcm., 16,251 (1877). (61) MORRELL, (62) REEDY,J. H., "Theoretical Qualitative Analysis," McGraw -Hill Baok Company, Inc.. New York, 1938, p. 262. R. STERN,Z . anal. Chm., 60, . . FEJ~L!-_F,~,AND
.
a1 (IWLl).
(64) A m c ~F. , W., J . Soc. Chcm. Ind., 34,641 (1915). (65) ILINSKY-KNORRE, Ber., 18, 699 (1885).
..- .",, .
a,..-.-."......u.A.
..T ...
(66) HAMMETT. L. P.. AND C. T. SOTTERY, 1.Amer. Chem. Soc., 47, 142 (1925). (67) REEDY,J. H., "Theoretical Qualitative Analysis." McGraw-Hill Book Comoanv. Inc.. N ~ WYork. 1938, D. 245. (68) AGOSTINI.P., Ann. chim. applicate, 19, 164 (1929). S E N ~ IC, . , p ~ ~ R ~ _ _ T _ g s ~Ann. o n r , chim. ap-
472) REEK , sis," MCG&W (73) Chrom (74)
250 (1909). (75) RIESENPELD, E., Ber., 47B. 548, 553 (1914). (76) FRESENIUS,W., AND F. RWPERT, Z. anal. Chem., 30,677 (1891). R., AND E. GXESSMANN, Be?., 42. (77) WEINLAND, 3881 (1909); Z.'anorg. Chem., 66, 157 (1910). P.. Chem. Zen&., 2, 709 (1901). (78) CAZENEUYE.
n*-:.. xcL.AL
.-...
(79) ROSENHEIM, A., 2.enorg. Chcm., 27,298 (1901). (80) HBLLER,K., AND P. KRUMHOLZ. Mikrochemie, 7. 213 (1929). H. J., AND H. B. VAN VALKEN(81) SCHLESINGER, BURGH, J . Amer. Chem. Soc., 53, 1212 (1931). (82) ARDAGH, E. G. R., AND G. R. BONGARD. Id. Eng. Chem., 16, 297-99 (1924).
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