Barium Nitride, Ba₃N₂

As in the case of the other alkaline earths, an impure barium nitride was first obtained by heating barium amalgam in a current of nitrogen when the mercury distils off, leaving, in general, a fused compact mass with a crystalline fracture, but sometimes yellowish needles. Metallic barium absorbs nitrogen at 260°-600° C. to form the Barium Nitride, Ba₃N₂. It may also be formed as a voluminous yellow powder, along with ammonia, by heating the amide, Ba(NH₂)₂, to above 650° C., or in vacuo at 400°-450° C. The reaction is reversible.

Barium nitride is an orange-yellow solid, fusible above 1000° C. and slightly volatile. With water, barium hydroxide and ammonia are formed. At red heat it reacts energetically with carbon monoxide, giving barium hydroxide and cyanide. Maquenne suggests that nitride formation precedes that of the cyanide in the production of the latter.

When hydrogen is passed over the nitride at 300° C. the hydride is formed and nitrogen liberated, ammonia being also evolved, especially if the temperature be raised. As the hydride may again be converted into the nitride by heating in nitrogen, these reactions might form the basis of a method for the synthesis of ammonia. The molecular heat of formation is 149.4 Cal.