Calcium Azide, Ca(N₃)₂

Calcium Azide, Ca(N₃)₂, is obtained by treating lime with a dilute solution of hydrazoic acid, and evaporating over sulphuric acid, or by boiling freshly precipitated calcium hydroxide in excess with a solution of ammonium azide. It forms small, white, hemispherical aggregates of rhombic crystals which explode violently on heating, but not by shock, the explosion temperature being 158° C.; nitrogen is evolved and metallic calcium remains.

It is hygroscopic, readily soluble in water, and isomorphous with barium and strontium azides.

Tiede suggested that the azides of the alkalies and the alkaline earths might be used for the preparation of pure nitrogen by decomposing them in a Gaede vacuum. The temperature at which the evolution of nitrogen from calcium azide begins under these conditions is 110° C., but 100° C. is then sufficient to maintain the reaction.

Calcium azide is very soluble in water, 100 parts dissolving 38.1 parts of the salt at 0° C., and 45.0 parts at 15.2° C. It is only slightly soluble in absolute alcohol and insoluble in ether. The aqueous solution can be evaporated without change.