Barium chloride

Barium chloride is the chemical compound with the formula BaCl2. It is one of the most important water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic.

Structure and properties
BaCl2 crystallizes in both the fluorite and lead chloride motifs, both of which accommodate the preference of the large Ba2+ ion for coordination numbers greater than six. In aqueous solution BaCl2 behaves as a simple salt; In water it is a 1:2 electrolyte and the solution exhibits a neutral pH.

Barium chloride reacts with sulfate ion to produce a thick white precipitate of barium sulfate.
 * BaCl2(aq) +  SO42-  →  BaSO4(s)  +  2 Cl-(aq)

Oxalate effects a similar reaction:
 * BaCl2(aq) +  Na2C2O4(aq)  →  BaundefinedC2O4 (s)  +  2 NaCl(aq)

Preparation
Although inexpensively available, barium chloride can be prepared from barium hydroxide or barium carbonate, the latter being found naturally as the mineral witherite. These basic salts react with hydrochloric acid to give hydrated barium chloride. On an industrial scale, it is prepared via a two step process from barite (barium sulfate)[4]:
 * BaSO4 +  4 C  →  BaS  +  4 CO

This first step requires high temperatures.
 * BaS +  CaCl2  →  BaCl2  +  CaS

The second step reqiures fusion of the reactants. The BaCl2 can then be leached out from the mixture with water.

Uses
As a cheap, soluble salt of barium, barium chloride finds wide application in the laboratory. It is commonly used as a test for sulfate ion (see chemical properties above). In industry, barium chloride is mainly used in the purification of brine solution in caustic chlorine plants and also in the manufacture of heat treatment salts, case hardening of steel, in the manufacture of pigments, and in the manufacture of other barium salts. BaCl2 is also used in fireworks to give a bright green color. However, its toxicity limits its applicability.

Safety
Barium chloride, as other water-soluble barium salts, is toxic. Amounts as of 2g to 4g can cause death. Barium chloride is toxic when swallowed or inhaled.

In the case of barium chloride ingestion, sodium sulfate solution can be used since sulfates combine with barium cations creating an insoluble precipitate. Formation of this insoluble precipitate thus prevents barium from being absorbed by the organism.