Strontium Orthoarsenate

Description

Strontium Orthoarsenate, Sr₃(AsO₄)₂, may be prepared by neutralizing aqueous arsenic acid with strontium hydroxide water slurry, or by adding ammonia to a solution of strontium monohydrogen arsenate in dilute hydrochloric acid. In either case, the precipitate is separated and well washed with water. The salt may also be obtained by fusing together at 450°C equal quantities of sodium chloride and sodium orthoarsenate and adding the required proportion of strontium oxide. After cooling, the sodium salts are removed by washing with water.

Physical properties

Colorless rhombic crystals, of density 4.601 g/cm3, are obtained that are readily soluble in dilute acids. The salt melts at 1635°C. When heated at 400–450°C in hydrogen, reduction occurs to give strontium oxide, arsenic trioxide and water.