Zinc Phosphite, ZnHPO₃

Zinc Phosphite, 2ZnHPO₃.5H₂O, is prepared by neutralising a solution of phosphorus trichloride in water with sodium carbonate and adding zinc sulphate at boiling heat. It is very soluble, does not alter over sulphuric acid, decomposes into ZnHPO₃.2H₂O between 100° C. and 120° C., and loses all its water at 250° C. The anhydrous salt was also prepared by diluting a solution of the hydrated salt in free acid.