2 CrI3 + 28 KOH + 9 Cl2 → 6 KIO + 18 KCl + 2 K2CrO4 + 14 H2O
This is an oxidation-reduction (redox) reaction:
6 I-I - 12 e- → 6 II (oxidation)
18 Cl0 + 18 e- → 18 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.