Haber process
The Haber process, also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. It converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using finely divided iron metal as a catalyst: N 2 + 3 H 2 ↽ − − ⇀ 2 NH 3 Δ H 298 K ∘ = − 92.28 kJ per mole of N 2 {\displaystyle {\ce {N2 + 3H2 <=> 2NH3}}\qquad {\Delta H_{\mathrm {298~K} }^{\circ }=-92.28~{\text{kJ per mole of }}{\ce {N2}}}} This reaction is exothermic but disfavored in terms of entropy because four equivalents of reactant gases are converted into two equivalents of product gas.