Chromium Monophosphide, CrP

Chromous Phosphide or Chromium Monophosphide, CrP, can be obtained by heating chromic chloride either with phosphorus in presence of hydrogen or in gaseous hydrogen phosphide; by heating a mixture of finely divided chromium and copper phosphide in the electric furnace, the copper being removed from the product by treatment with nitric acid; or by the reduction of chromic phosphate by strongly heating with charcoal. It is a grey crystalline solid, having the appearance of graphite; density 5.71. It is unaffected by ordinary acids, but will dissolve in a mixture of nitric and hydrofluoric acids. When heated in air it oxidises slowly. Chlorine attacks it with incandescence. It is decomposed by fused caustic potash, hydrogen being evolved and potassium chromate formed.