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84. IRON GROUP (III.).—Separation of Iron, Nickel, To the filtrate from the sulphides of the Cu and As groups add (NH4) HO and shake for some time. Filter (preferably by the Bunsen pump). Wash the precipitate with cold
NiS and Cos.
Test for Co by
borax bead. Dissolve the black
residue in H Cl
and K Cl 03. Boil down just
to dryness, di
METHOD I. Cr Is Absent.
Boil down with a little KCI 03 till it smells of Cl. Add pure NaHO till strongly alkaline. Filter. RESIDUE.
Al, Zn. Divide into
of acetic acid,
boil for a few minutes, NaClO in excess, and boil again. A black precipitate indicates Nickel. The filtrate from this precipitate may be tested for Co
by evaporating to dryness, and fusing in a borax bead. Blue colour indicates Cobalt.
Wash with hot H2O, dissolve in HCl,
add (NH4)HO, and filter.
2. Add H Cl (NH4)HO till altill acid, then kaline. A white precipitate indicates AlumiCo nium. Confirm along with the by flame re
KNO3. A green residue indicates Manganese. Traces of Ni and are found
ferric salt, the
Cobalt, Aluminium, Zinc, Manganese, and Chromium.
(till alkaline) + NH4Cl + (NH4)2S. Warm the mixture gently in a small flask well with H2O, containing (NH4)2S, and finally once with H O alone. Treat dilute HCl, and filter.
(Green or violet if Cr be present. Boil down a portion and test for Cr by borax bead. Adopt Method I. if absent, Method II. if present.)
METHOD II. Cr Is PRESENT.
Boil down with a little KClO3 till it smells of Cl. Add Na2CO3 or NaHO till just neutral or slightly acid; allow to become perfectly cold. Add excess of BaCO3, place in a flask, cork up and shake well, allow to stand till clear. Filter. RESIDUE. FILTRATE.
Fe2(HO), Cr2 (HO), Al2(HO), (also excess of BaCO3). Wash well, boil with pure NaHO, and filter; add HCl to the filtrate, and then (NH4) HO till alkaline. A white precipitate indicates Aluminium. Confirm by flame-reaction. Fuse the residue insoluble in NaHO with a mixture of Na2CO3 and KNO3, extract with water, and filter. RESIDUE. FILTRATE.
Dissolve in H Cl, and test with K4Fe(CN)6. A blue precipitate indicates Iron.
Yellow in colour. Acidify with acetic acid; add lead acetate. A bright yellow precipitate indicates Chromium.
Zn, Mn. Precipitate the Ba present with H2SO4 in the hot solution. Boil well, and filter; add NaHO. Precipitate indicates Manganese. Confirm by fusing with Na2CO3 and KNO3 on platinum foil. To the filtrate from Mn (HO)2
Reactions of the Metals of the Barium Group.
85. Metals whose carbonates are insoluble in water, and whose solutions are precipitated on the addition of (NH4)2CO3: as, however, the carbonates are soluble in acids, the solution, if acid, must be neutralized by addition of (NH1)HO.
Barium, Strontium, Calcium.
BARIUM. Ba, c.w. 137.
I. (NH4)2CO3 produces a white precipitate of BaCO3, soluble in acids, and to a slight extent in NH4Cl.
2. K,CO, or Na,CO, produces also a precipitate of BaCO3, insoluble in excess of either reagent.
3. H2SO4 or any soluble sulphate produces, even in dilute solutions, a heavy white precipitate of BaSO4, insoluble in acids, alkalies, or salts of ammonium.
4. CaSO4 or SrSO4 produces an immediate white precipitate of BaSO4.
5. H2SiF produces a white precipitate of BaSiF。. 6. C2(NH4)2O4 produces a white precipitate of C,BaO4, soluble in HCl and in HNO3.
7. K,CrO4 produces a yellow precipitate of BaCro insoluble in C2H4O2, but soluble in HCl and HNO3.
8. Heated in the lamp flame a green coloration is produced, especially on moistening the salt with HCI.
86. STRONTIUM. Sr, c.w. 87'5.
1. (NH4)2CO, or K2CO, precipitates white SrCO3, soluble in acids, but less soluble in NH4Cl than BaCO3.
2. H2SO, produces a white precipitate of SrSO which is much less insoluble in H2O than BaSO4, and it therefore precipitates from dilute solutions only on standing or warming. SrSO4 is slightly soluble in HCl. 3. CaSO4 produces, after standing some time, a white precipitate of SrSO4.
4. H2SiF does not precipitate strontium solutions. 5. C2(NH4)2O4 produces a white precipitate of C2SrO4, soluble in HCl and in HNO3, also to a slight extent in NH4Cl, but very sparingly in C2H4O2.
6. K2CrO4 produces, only in concentrated solutions, a yellow precipitate of SrCrO4, soluble in C2H4O2.
7. Heated in the lamp flame a crimson coloration is produced, especially on moistening the salt with HCl.
87. CALCIUM. Ca, c.w. 40.
I. (NH4)2CO3 or K,CO, produces a white precipitate of CaCO3, which becomes crystalline on heating.
2. H2SO4 precipitates from strong solutions of calcium salts CaSO4, as a white precipitate, which dissolves in a large excess of water, and also in acids. 3. CaSO, produces no precipitate.
4. H2SiF produces no precipitate.
5. C2(NH4)2O4 produces, even in dilute solutions, a white precipitate of C2CaO,, soluble in HCl or HNO3, but insoluble in C2H2O, or in C2H402
6. Heated in the lamp flame, a dull red coloration is produced, especially on moistening the salt with HCl. This reaction is imperceptible in presence of Ba or Sr salts.
88.-CALCIUM GROUP (IV.).
Separation of Barium,
Heat filtrate from iron group, add to the hot solution NH4Cl and and add CaSO4 solution. An immediate precipitate indicates Barium; solution. (Test another portion with Sr SO4 for Ba.) To another portion of Neutralize filtrate with (NH4)HO, and add C2(NH4)2O4. An immediate
Dissolve the carbonate in HCl, and evaporate to dryness. Treat the residue with strong alcohol. Filter.