Page images
PDF
EPUB

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 RESIDUE.

NiS and Cos.

a

Test for Co by borax bead. Dissolve the black

METHOD 1. Cr Is ABSENT. residue in HCI and K CI 03.

Boil down with a little KCIO3 till it smells of Cl. Add Boil down just

pure NaHO till strongly alkaline. Filter. to dryness, diRESIDUE.

FILTRATE. lute with H,O, Fe2(HO), Mn (HO).

AJ, Zn. add KCN in ex- Wash with hot H,O, dissolve in HCl,

Divide

into cess, then a drop of acetic acid, add (NH4)HO, and filter.

two parts. RESIDUE.

FILTRATE. 1. Add HS boil for a few

or (NHA 3.A minutes, add Fe, (HO)

Mn.

white preci itate NaClO in excess, Dissolve in Boil down and

indicates Zinc. and boil again. HCI. Test with ignite, to expel

Confirm by A black preci- K.Fe(CN)6. Blue salts of ammo

flame-reaction. pitate indicates precipitate indi- nium.

Fuse

2. Add HCI Nickel. The cates Iron. To with NaHO and

till acid, then filtrate from this ascertain whether | KNO3. A green

(NH4)HO till alprecipitate may the iron is pre

residue indicates

kaline. A white be tested for Co sent as ferrous or Manganese.

precipitate indiby evaporating ferric salt, the Traces of. Ni and

cates Alumi. to dryness, and original solution Co found

nium. Confirm fusing in a borax must be tested along with the

by flame bead. Blue cowith K4Fe(CN)6, Mn.

action. lour indicates and K3Fe(CN)6. Cobalt.

are

1

re

F.

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.

FILTRATE.

1

Cr, Al, Fe, Zn, and Mn. (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. Cris Present. Boil down with a little KCIO3 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.

FILTRATL. 1

Fe(HO), Cr, (HO), Al2(HO). (also excess of BaCO3). Zn, Mn.

Wash well, boil with pure NaHO, and filter ; add Precipitate the HCl to the filtrate, and then (NH4) HO till alkaline. A Ba present with white precipitate indicates Aluminium. Confirm by H2SO4 in the hot flame-reaction. Fuse the residue insoluble in Na HO with a solution. Boil mixture of Na,CO3 and KNO3, extract with water, and filter. well, and filter ; RESIDUE.

FILTRATE.

add NaHO. Pre

cipitate indicates Pe (HO)

or,

Manganese. Dissolve in HCl, and test

Yellow in colour. Acidify Confirm by fuswith K4Fe(CN)6. A blue pre

with acetic acid ; add leading with Na,CO3 cipitate indicates Iron. acetate. A bright yellow pre- and KNO3 on

cipitate indicates Chro- platinum foil. To mium.

the filtrate from the Mn (HO) add (NH4)2S. A white precipitate indicates Zinc. Confirm by flame-reaction.

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 (NH4)HO.

[ocr errors]

Barium, Strontium, Calcium.
BARIUM. Ba, c.w. 137.

1. (NH),CO, 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 BaSO insoluble in acids, alkalies, or salts of ammonium.

4. CaSO4 or SrS04 produces an immediate white precipitate of BaSO4.

5. H SiFo produces a white precipitate of Ba Sifa 6. C,(NH), 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 HCl.

86. STRONTIUM. Sr, c.w. 87.5.

1. (NH),C0g or K,CO, precipitates white SrCO3, soluble in acids, but less soluble in NH4Cl than BaCO3

6

2. H,SO, produces a white precipitate of Srson, which is much less insoluble in H,O than BaSO4, and it therefore precipitates from dilute solutions only on standing or warming. SrS04 is slightly soluble in HCl.

3. CaSO4 produces, after standing some time, a white precipitate of SrSO4.

4. H2SiFo does not precipitate strontium solutions. 5. C2(NH),04 produces a white precipitate of

20 CqSrO4, soluble in HCl and in HNO3, also to a slight extent in NH,C1, but very sparingly in C2H4O2.

6. K,Cr04 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 HCI.

3

87. CALCIUM. Ca, c.w. 40.

1. (NH),CO, or K,COproduces 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. H,SiFo produces no precipitate.

5. C2(NH2)20, produces, even in dilute solutions, a white precipitate of C CaO,, soluble in HCl or HNO3, but insoluble in C,H,O, or in C2H4O2.

6. Heated in the lamp flame, a dull red coloration is produced, especially on moistening the salt with HCI. This reaction is imperceptible in presence of Ba or Sr salts.

4

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 Cz(NH4)204. An immediate

TO TEST FOR

I. Ba PRESENT. Ca ABSENT.

II. Ba ABSENT. Dissolve the carbonate in HCl, and evaporate to Dissolve as before, and dryness. Treat the residue with strong alcohol.

Filter, and Filter.

RESIDUE.
RESIDUE.
FILTRATE.

Srsos
Bać,

Sr.

If small, burn the filConfirm by flame test.

Confirm by lighting ter in the reducing gas Green coloration indi. the alconolic solution.

flame to convert SrS04 cates Barium. Crimson coloration in

into SrS: moisten with dicates Strontium.

HCI, and test in the lamp-flame. Crimson coloration indicates Strontium.

ANOTHER

Dissolve in HNO3, ness. Treat with strong

RESIDUE.
Sr(NO3)2:

) Confirm as above.

« PreviousContinue »