N^-IIIH₃ + 2 O₂⁰ → HN^VO₃^-II + H₂O^-II

This is an oxidation-reduction (redox) reaction:

N^-III - 8 e^- → N^V (oxidation)

4 O⁰ + 8 e^- → 4 O^-II (reduction)

NH₃ is a reducing agent, O₂ is an oxidizing agent.