Synthetic Inorganic Chemistry

BARIUM CHLORIDE 147

PREPARATION 9

BARIUM CHLORIDE, BaCl 2 -2H 2 O

A general method of preparing a salt is by neutralizing an acid

with the appropriate base. It is almost as effective to use the

carbonate of the metal as the base, because carbonic acid is so

easily displaced. Barium carbonate is found naturally as the

mineral witherite, which contains iron and silica as impurities.

In this country barium carbonate (known as "precipitated"

barium carbonate) is made commercially by reducing barium sul-

phate to sulphide, and converting the latter to the carbonate by

means of carbon dioxide. The resulting product frequently con-

tains silica, barium sulphate, barium sulphide, and iron as im-

purities. After the acid has been neutralized with barium car-

bonate a little barium peroxide is added to the mixture. The

barium peroxide is nearly insoluble, but it does hydrolyze to a

small extent forming barium hydroxide and hydrogen peroxide.

Any iron present is oxidized and precipitated as ferric hydroxide.

4 BaO 2 + 8 H 2 O + 4 FeCl 2 = 4 Fe(OH) 3 + 4 BaCl 2 + 2 H 2 O 2
2 H 2 O 2 -* 2 H 2 O + O 2
After the solution has been filtered it is made acid with hydro-
chloric acid.
Materials: barium carbonate, BaCC>3.
barium peroxide, BaO 2 , 3 grams,
hydrochloric acid.
Apparatus: 8-inch porcelain dish.
5-inch funnel.
8-inch crystallizing dish and cover,
two 5-inch watch glasses,
iron ring and ring stand.
Bunsen burner.
Procedure: The hydrochloric acid obtained in Preparation 7
may be used for this preparation or 166 cc. of 12N HC1 (2 F.W.)
may be used. Calculate the weight of barium carbonate required
to convert your sample of hydrochloric acid into barium chloride.
Pour the acid into an 8-inch porcelain evaporating dish and add
enough water to make 600 cc. of solution. Remove 10 cc. of this
dilute acid and save it for use later in the preparation. Add the