Video: Sulfite ion as a reducing agent

Sulfite ion will reduce purple permanganate ion to colorless manganese(II) ion in acid solution.

SO32-(aq) + H2O(l) ® SO42-(aq) + 2 H+(aq) + 2 e-
MnO4-(aq) + 8 H+(aq) + 5 e- ® Mn2+(aq) + 4 H2O(l)