C0 + H2ISVIO4 H20 + SIVO2 + CIVO2

This is an oxidation-reduction (redox) reaction:

C0 - 4 e- CIV (oxidation)

SVI + 2 e- SIV (reduction)

2 HI + 2 e- 2 H0 (reduction)

C is a reducing agent, H2SO4 is an oxidizing agent, H2SO4 is an oxidizing agent.