4 CaXXIII22-I + 5 H2SVIO4 4 CaIISVIO4 + H2S-II + 44 I20 + 4 H2O

This is an oxidation-reduction (redox) reaction:

SVI + 8 e- S-II (reduction)

88 I-I - 88 e- 88 I0 (oxidation)

4 CaXXII + 80 e- 4 CaII (reduction)

Change the oxidation states