2 CrIIICl3-I + 16 NaOH + 3 Cl20 2 Na2CrVIO4 + 12 NaCl-I + 8 H2O

This is an oxidation-reduction (redox) reaction:

6 Cl0 + 6 e- 6 Cl-I (reduction)

2 CrIII - 6 e- 2 CrVI (oxidation)

Change the oxidation states