The number of mole of `KMnO_(4)` that will be needed to react completely with one mole of ferrous oxalate in acidic solution is:

Options

A. 0.2 moles
B. 0.6 moles
C. 0.4 moles
D. 7.5 moles

Answer

2

Explanation

`underset("Ferrous oxalate")(Fe(COO)_(2)) rarr Fe^(2+)+(COO^(-))_(2)`
`underset(O.N=+2)(Fe^(2+)) overset(MnO_(2)^(+))(rarr) underset(O.N=+3)(Fe^(3+))`

In the first reaction, O.N changes by 1 unit while in the second reaction O.N changes by 2 units. Thus, total change in O.N is by 3 units. This implies the one mole of ferrous oxalate contains 3 equivalents.
`underset(Mn=+7)underset(O.N of)(MnO_(4)^(-))rarr underset(Mn=+2)underset(O.N. of)(Mn^(2+)) ("acidic medium")`
Since in the above reaction, O.N. of Mn changes by 5 units, one mole of `MnO_(4)^(-)` contains 5 equivalents. According to the law of equivalence, we need 3 equivalents of `MnO_(4)^(-)` to oxidize one mole of ferrous oxalate completely in acidic medium. Since 5 equivalents of `MnO_(4)^(-)` come from 1 mole, 3 equivalents of `MnO_(4)^(-)` will come from
`=1/5xx3`
`=0.6 mol`