2 (NH4)2Cr2VIO7-II 2 Cr2IIIO3-II + 4 NH3 + 3 O20 + 2 H2O-II

This is an oxidation-reduction (redox) reaction:

4 CrVI + 12 e- 4 CrIII (reduction)

6 O-II - 12 e- 6 O0 (oxidation)

(NH4)2Cr2O7 is an oxidizing agent, (NH4)2Cr2O7 is a reducing agent.