Question

What happens when so2 is passed in acidified kmno4 solution?

Answer 1

kmno4 is a very strong oxidising agent whereas the so2 is strong reducing agent so the so2 reduces Mn. The equation for the reaction is 5so2+2kmno4+2h2o= 2h2so3+2mnso4+k2so4.

both reactions are viable as the formation of mnso4 takes place and kmno4 disappears decolorisation of the reaction occurs

Answer 2

KMNO4 is actually a very  very strong oxidizing agent but   SO2 is strong reducing agent so that  SO2 reduces Mn.

The equation of the reaction is given by following,

5SO2+2KMNO4+2H2O= 2H2SS3+2MNSO4+K2SO4.

both reactions are viable as the formation of MNSO4 takes place and KMNO4 disappears decolonization of the reaction occurs