State what will be observed when SO2 gas is passed through acidified KMnO4 solution? ?

Question

State what will be observed when SO2 gas is passed through acidified KMnO4 solution? ?

Answer 1

Sounds like a job for REDOX MAN!

In lieu of a super-hero, I'll have a go at it.  The manganese in MnO4- will be reduced to Mn2+, and the sulfur in SO2 will be oxidized, probably to SO4^2-

You will see the disappearance of the purple color of the permanganate, and depending on the concentration of KMnO4, you may see a slightly yellow color due to Mn2+.  And you may observe the disappearance of some of the bubbles as the SO2 dissolves in water.

If you were inclined to write the equation, you can finish it up below.

2(8H+ + MnO4- + 5e- --> Mn2+ + 4H2O)  --  reduction half-reaction

5(SO2 + 2H2O --> SO4^2- + 4H+ + 2e-)  --  oxidation half-reaction

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You can add the reactions here to get the balanced net ionic equation.

Remember to cancel out the some of the H2O and H+ on each side.

Answer 2

I would add only that Mn2+ isalmost colorless (VERY pale pink) and that the trace of yellow sometimes seen is a tiny smear of Mn(III) or Mn(IV) oxide if conditons weren't acidic enough.