(N-IIIH4)2Cr2VIO7 + 4 KI-I + 7 H2SVIO4 2 (NIIH4)SIIO4 + 2 I20 + Cr2III(SVIO4)3 + 2 K2SVIO4 + 7 H2O

This is an oxidation-reduction (redox) reaction:

2 SVI + 8 e- 2 SII (reduction)

4 I-I - 4 e- 4 I0 (oxidation)

2 N-III - 10 e- 2 NII (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

H2SO4 is an oxidizing agent, KI is a reducing agent, (NH4)2Cr2O7 is a reducing agent, (NH4)2Cr2O7 is an oxidizing agent.