Barium Chromate, BaCrO₄

Barium Chromate, BaCrO₄, is obtained as a pale yellow powder of density 4.3 – 4.5 by precipitation from solutions of a chromate and a soluble barium salt. It can be prepared in the form of rhombic crystals, isomorphous with barium sulphate and of density 4.6, by fusing sodium and potassium chromates with barium chloride.

Barium chromate is stable at red heat, and for that reason has been employed in painting porcelain. It is practically insoluble in acetic acid, but is readily dissolved by hydrochloric, nitric, and chromic acids. It is decomposed by sulphuric acid and by a hot solution of sodium carbonate. In the latter case a definite equilibrium point, between barium chromate and sodium carbonate on the one hand, and barium carbonate and sodium chromate on the other, is reached.

The solubility has been determined by electrical conductivity methods.

Temperature, °C	-0.88	16.07	17.42	18	28.08
Mgm. BaCrO4 per litre	2.04	3.37	3.48	3.52	4.36
Milli-equiv. per litre	0.0161	0.0266	0.0275	0.0278	0.0344

Barium chromate is soluble in molten sodium nitrate. By precipitation from concentrated solutions a barium potassium chromate, BaCrO₄.K₂CrO₄, and a barium ammonium chromate, BaCrO₄.(NH₄)₂CrO₄, may be obtained.