Ammonia is prepared commercially in vast quantities. The major method of production is the Haber process , in which nitrogen is combined directly with hydrogen at high temperatures and pressures in the presence of a catalyst. It is obtained as a byproduct of the destructive distillation of coal. Ammonia is also prepared synthetically by the cyanamide process: nitrogen gas combines with calcium carbide, CaC 2, at high temperatures to form calcium cyanamide, CaCN 2, and carbon; the calcium cyanamide reacts with steam to form calcium carbonate, CaCO 3, and ammonia. For use in the laboratory, ammonia is prepared by heating an ammonium salt with a strong base. It can also be prepared by reacting a metal nitride with water.
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