BARIUM HYPOPHOSPHITE

Description

Barium hypophosphite has the formula, Ba(H2PO2)2, and the molecular weight of 267.30388 g/mol. This salt can be prepared by the aqueous reaction of the carbonate or oxide with H3PO2:
BaO + 2H3PO2 ? Ba(H2PO2)2
The salt is slightly soluble in water (3.62 g/100 ml at 20°C) so that the solution must be evaporated to obtain crystals. This procedure forms barium hypophosphite monohydrate, Ba(H2PO2)2·H2O, whose CAS number is 14871-79-5. Its molecular weight is 285.320 g/mol. It occurs as monoclinic plates with a density of 2.94 g/cm³. It is soluble in water but insoluble in alcohol. Therefore, the addition of alcohol during evaporation serves to hasten the crystallization process from aqueous solution. Heating to about 110°C causes the loss of the water of hydration to form the anhydrate. The anhydrate is soluble in water at about 35 g/100 ml at 20°C but only 30 g/100 ml at 100°C.

Chemical properties

White, crystalline powder; odorless. Soluble in water; insoluble in alcohol.

The Uses of BARIUM HYPOPHOSPHITE

The major usage of barium hypophosphite has been as a source of hypophosphorous acid because the addition of H3PO4 to a solution allows the separation of the very insoluble BaSO4. Although this salt is mentioned in a few patents concerning metal surface finishing, electroplating, chemical intermediates and as a source of hypophosphite anions, it is the calcium salt that is preferred since it is lower in cost and easier to use.

The Uses of BARIUM HYPOPHOSPHITE

Nickel plating.