2 CrI3 + 52 KOH + 21 Cl2 → 2 K2CrO4 + 6 KIO3 + 42 KCl + 26 H2O
This is an oxidation-reduction (redox) reaction:
6 I-I - 36 e- → 6 IV (oxidation)
42 Cl0 + 42 e- → 42 Cl-I (reduction)
2 CrIII - 6 e- → 2 CrVI (oxidation)
CrI3 is a reducing agent, Cl2 is an oxidizing agent, CrI3 is a reducing agent.