Question

Question : State whether the following are true or false.

SO2 gas changes the colour of a KMnO4(aq) solution

They have taken this as false and given the following equation:

SO2+H2O+2KMnO4-->K2SO4+MnSO4+H2SO4 (not balanced)

But why they have taken this as false when Mn2+ created here is colourless (Does K2SO4 has a colour?)

When the medium is acidic,the colour of the solution does change from purple(MnO4^- is purple and SO2 is colourless) to colourless (Mn^2+) right?

And they haven't given whether the medium is acidic/basic,too.
[From what I've learned this reaction takes place in acidic medium(MnO4^- -->Mn^2+) ]

And I've learned that in basic medium they react as follows;

MnO4^- + SO2+4OH^- -->MnO2+SO4^2- + H2O (not balanced)

And in this case the colour of the solution should change from purple(MnO4^-) to brown/black (MnO2)

So,to my knowledge, in these both cases,the colour of the solution does change.

So I don't understand why they've taken the above statement as false.

Answer 1

I don't understand it either. I don't see anything wrong with your reasoning.

Answer 2

Hmm..Thank you very much

Answer 3

I agree.