2 FeIIS-II + 4 HINVO3 + H2ISVIO4 3 H20 + 4 NIIO + Fe2III(SVIO4)3

This is an oxidation-reduction (redox) reaction:

2 S-II - 16 e- 2 SVI (oxidation)

6 HI + 6 e- 6 H0 (reduction)

4 NV + 12 e- 4 NII (reduction)

2 FeII - 2 e- 2 FeIII (oxidation)

Change the oxidation states