2 CrVIO3 + 2 N-IIIH3 N20 + Cr2IIIO3 + 3 H2O

This is an oxidation-reduction (redox) reaction:

2 N-III - 6 e- 2 N0 (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

NH3 is a reducing agent, CrO3 is an oxidizing agent.