There are several methods for producing nitric acid from nitrogen, but two common methods are:
1. Ostwald process:
4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)
2 NO(g) + O2(g) → 2 NO2(g)
3 NO2(g) + H2O(l) → HNO3(aq) + HNO2(aq)
Overall equation:
4 NH3(g) + 3 O2(g) + H2O(l) → 2 HNO3(aq) + 2 NO(g)
2. Birkeland-Eyde process:
N2(g) + 3 H2(g) → 2 NH3(g)
2 NH3(g) + 3 O2(g) → 2 NO(g) + 3 H2O(g)
2 NO(g) + O2(g) → 2 NO2(g)
3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)
Overall equation:
N2(g) + 3 O2(g) + 3 H2(g) → 2 HNO3(aq)