2 Cr(OH)3 + 3 Cl2 + 10 KOH → 8 H2O + 2 K2CrO4 + 6 KCl
This is an acid-base reaction (neutralization): Cr(OH)3 is an acid, KOH is a base.
This is an oxidation-reduction (redox) reaction:
6 Cl0 + 6 e- → 6 Cl-I (reduction)
2 CrIII - 6 e- → 2 CrVI (oxidation)
Cl2 is an oxidizing agent, Cr(OH)3 is a reducing agent.