Ammonia is prepared in the laboratory by heating a mixture of NH₄CI and slaked lime, Ca ( OH )₂

                                                 

Moist NH₃ gas is dried over quick lime, CaO . However, it cannot be dried over conc. H₂SO₄, P₂O₅ because being basic it forms salts with them. Anhydrous CaCI₂ also cannot be used because it forms a complex CaCI₂.8NH₃ with it.

MANUFACTURE OF AMMONIA :

(i) Ammonia is manufacture by Haber’s process. A mixture of pure N₂ and H₂ (in the ratio 1 : 3 by volume) is compressed to 200 – 1000 atmospheres and passed over finely divided Fe (as catalyst) and Mo (as promoter) at 750K

N2 + 3H2 2NH₃ + 93.6KJ ml^-1

Favorable conditions for maximum yield of NH₃ are :

(a) excess of reactants ( N₂ and H₂ ) (b) high pressure (c) low temperature and (d) use of catalyst and a promoter.

(ii) By the hydrolysis of calcium cyanamide ( CaCN₂ ) with super-heated steam at 450K . CaCN₂ itself is obtained by heating CaC₂ and N₂ at 1270K .