Large scale production of ammonia is carried by Haber's process as :

N₂(g) + 3H₂(g) ⇌ 2NH₃(g) ΔH_f = 46.1 kJ/mol

In the process, the two gases (N₂ and H₂) are mixed in a molar ratio of 1 : 3 and then compressed to the pressure of 200 atm. The mixture then reacts on Iron oxide catalyst (highly porous and finely divide) containing small amounts of promoters (molybdenum or alumina (Al₂O₃) and potassium oxide (K₂O). The reaction is carried out at a high temperature of about 700 K. The ammonia gas is obtained which is then cooled to liquid ammonia and the unreacted molecules of N₂ and H₂ are directed back to the compression chamber.