4 FeIIS2-I + 11 O20 8 SIVO2-II + 2 Fe2IIIO3-II

This is an oxidation-reduction (redox) reaction:

8 S-I - 40 e- 8 SIV (oxidation)

4 FeII - 4 e- 4 FeIII (oxidation)

22 O0 + 44 e- 22 O-II (reduction)

Change the oxidation states