Barium Hypophosphate, BaPO₃

Barium Hypophosphate, BaPO₃, is formed as a white precipitate by the action of neutral sodium hypophosphate on barium chloride. It is insoluble in acetic acid, but readily soluble in hydrochloric and phosphoric acids. When heated it forms the pyrophosphate.

By dissolving the neutral salt in hypophosphoric acid and evaporating in the cold, or by precipitating barium chloride with acid sodium hypophosphate, acid barium hypophosphate, BaH₂(PO₃)₂.2H₂O, is obtained.

At 140° C. it slowly loses water of crystallisation, and at higher temperatures hydrogen escapes and burns, leaving barium metaphosphate. The salt may be purified by recrystallisation from very dilute boiling nitric acid.