2 Cr3I3 + 96 KOH + 39 Cl2 → 6 KIO4 + 78 KCl + 6 K2CrO4 + 48 H2O
This is an oxidation-reduction (redox) reaction:
6 I-I - 48 e- → 6 IVII (oxidation)
78 Cl0 + 78 e- → 78 Cl-I (reduction)
6 CrI - 30 e- → 6 CrVI (oxidation)
Cr3I3 is a reducing agent, Cl2 is an oxidizing agent, Cr3I3 is a reducing agent.