$\mathrm{N}_2 + 3\mathrm{H}_2 \rightleftharpoons 2\mathrm{NH}_3;$ $\Delta_f H = -46.1\,\text{kJ}\,\text{mol}^{-1}$ In accordance with Le Chatelier’s principle high pressure and lowtemperature would favour formation of ammonia. The optimumconditions for the production of ammonia are a pressure of about200 atm, a temperature of about 700K and use of a catalyst such as ironoxide with small amount of $\mathrm{K}_2\mathrm{O}$ and $\mathrm{Al}_2\mathrm{O}_3$ as promoters.