2 K(CrIII(O-IIH)4) + 3 H2O2-I + 2 KO-IIH 2 K2CrVIO4-II + 8 H2O-II

This is an oxidation-reduction (redox) reaction:

2 CrIII - 6 e- 2 CrVI (oxidation)

6 O-I + 6 e- 6 O-II (reduction)

Change the oxidation states