As2IIIS3-II + 5 Cl20 + 8 H2O 3 S0 + 2 H3AsVO4 + 10 HCl-I

This is an oxidation-reduction (redox) reaction:

2 AsIII - 4 e- 2 AsV (oxidation)

3 S-II - 6 e- 3 S0 (oxidation)

10 Cl0 + 10 e- 10 Cl-I (reduction)

Change the oxidation states