Question

How many mole of `FeSO_(4),H_(2)C_(2)O_(4)` and `FeC_(2)O_(4)` are oxidised separately by one mole of `KMnO_(4)` in acid medium?

Answer 1

`FeSO_(4)` : `Fe^(2+) rarr Fe^(3+) + e`
`Mn^(7+) + 5e rarr Mn^(2+)`
Thus, `5Fe^(2+) + Mn^(7+) rarr Fe^(3+) + Mn^(2+)`
or `5` mole of `FeSO_(4)` are oxidised by `1` mole `KMnO_(4)`.

`H_(2)C_(2)O_(4)`: `C_(2)^(3+) rarr 2C^(4+) + 2e`
`Mn^(7) + 5e rarr Mn^(2+)`
`5C_(2)^(3+) +2Mn^(7+) rarr 10C^(4+) + 2Mn^(2+)`
or `5//2` mole of `H_(2)C_(2)O_(4)` are oxidised by `1` mole `KMnO_(4)`.
`FeC_(2)O_(4)`: `Fe^(2+) +C_(2)^(3+) rarr Fe^(3+) + 2C^(4+) + 3e`
`Mn^(7+) + 5e rarr Mn^(2+)`
`5FeC_(2)O_(4) +3Mn^(5+) rarr 5Fe^(5+) rarr 5Fe^(3+) + 10C^(4+) + 3Mn^(2+)`
or `5//3` mole of `FeC_(2)O_(4)` are oxidised by `1` mole `KMnO_(4)`.