Question

If a solution contains 1 mol of KMnO4 in acidic medium, it will oxidize :

Answer 1

First thing you should know is how KMnO4 behaves in different mediums

In acidic medium, KMnO4 accepts 5 e-s , Mn changes its ox. no. from +7 to +2

In neutral medium, KMnO4 accepts 3 e-s , Mn changes its ox. no. from +7 to +4

In basic medium, KMnO4 accepts 1 e- , Mn changes its ox. no. from +7 to +6

2. Secondly , ferrous ion will always get oxidised to ferrate ,ie +2 to +3, that means it looses one e-. Oxalate ion gets oxidised to Carbon dioxide, ie carbon changes its . from +3 to +4, but oxalate ion contains two carbons, so it looses 2e-s. that means 1 mole ferrous oxalate is going to loose 3e-.

Now , we know from point 1 , that 1 mole KMnO4 in acidic medium can accept 5e-.

for 5e- ———- 1 mol KMnO4

1e- ————- 1/5 mol KMnO4

3e- —————3/5 mol KMnO4

I hope you understood . Thank you