4 N-IIIH3I + O20 6 H20 + 2 N2IO-II

This is an oxidation-reduction (redox) reaction:

12 HI + 12 e- 12 H0 (reduction)

4 N-III - 16 e- 4 NI (oxidation)

2 O0 + 4 e- 2 O-II (reduction)

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