A colourless solid, CaCN2, which sublimes at 1300°C. It is prepared by heating calcium dicarbide at 800°C in a stream of nitrogen:CaC2(s)+N2(g) → CaCN2(s)+C(s)The reaction has been used as a method of fixing nitrogen in countries in which cheap electricity is available to make the calcium dicarbide (the cyanamide process). Calcium cyanamide can be used as a fertilizer because it reacts with water to give ammonia and calcium carbonate:CaCN2(s)+3H2O(l) → CaCO3(s)+2NH3(g) It is also used in the production of melamine, urea, and certain cyanide salts.
CaC2(s)+N2(g) → CaCN2(s)+C(s)
CaCN2(s)+3H2O(l) → CaCO3(s)+2NH3(g)