Strontium Arsenide, Sr₃As₂

Strontium Arsenide, Sr₃As₂, may be prepared by reduction of strontium arsenate. This is best accomplished by rapidly heating with carbon to 1500° to 1600° C. If the heating is slow, reduction begins at about 800° C. yielding first the arsenite, arsenic then being lost and strontium oxide formed. Calcium arsenate behaves similarly. Strontium arsenide forms reddish-brown crystals, transparent in thin sections, and of density 3.6 at 15° C. It decomposes in contact with water, forming strontium hydroxide with liberation of arsine. It burns brilliantly when heated in oxygen or sulphur vapour. It reacts with fluorine at ordinary temperature with incandescence and formation of arsenic trifluoride. Similar reactions occur with chlorine at 160° C., with bromine at 200° C., and with iodine vapour at a higher temperature. It is a powerful reducing agent and attacks most metallic oxides and oxidising agents. When heated with carbon in an electric furnace it yields strontium carbide.