STRONTIUM ARSENIDE

Description

Strontium Arsenide, Sr3As2, may be prepared by the reaction of the elements or by the reduction of strontium arsenate. The latter method 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:
3Sr + 2As + heat ? Sr3As2
2Sr3AsO4 + 4C + heat ? Sr3As2 + 3SrO + 3CO + CO2
Strontium arsenide forms reddish-brown crystals, transparent in thin sections, with a density of 3.23 g/ cm3. It has the CAS number 39297-24-0. Its molecular weight is 1167.9668 g/mol. It decomposes in contact with water, forming strontium hydroxide with liberation of arsine. It burns brilliantly when heated in oxygen or sulfur vapor. It reacts with fluorine at room temperature with incandescence and formation of arsenic trifluoride. Similar reactions occur with chlorine at 160°C, with bromine at 200 °C, and with iodine vapor at a higher temperature. It is a powerful reducing agent and attacks most metallic oxides and oxidizing agents. It is considered as a “Dangerous Substance for the Environment” and is prohibited in Europe by the EEC.