Question

In order to oxidise a mixture of one mole of each of \[\ce{FeC2O4, Fe2(C2O4)3, FeSO4 and Fe2(SO4)3}\] in acidic medium, the number of moles of KMnO₄ required is ______.

Options

• 2

• 1

• 3

• 1.5

Answer 1

In order to oxidise a mixture of one mole of each of \[\ce{FeC2O4, Fe2(C2O4)3, FeSO4 and Fe2(SO4)3}\] in acidic medium, the number of moles of KMnO₄ required is 2.

Explanation:

The oxidation of a mixture of one mole of each of \[\ce{FeC2O4, Fe2(C2O4)3, FeSO4 and Fe2(SO4)3}\] in acidic medium is as follows.

\[\ce{FeC2O4 + MnO4^- -> Mn^{2+} + CO2 + Fe^{3+}}\]   ...(i)

\[\ce{Fe2(C2O4)3 + MnO_4^- -> Mn^{2+} + CO2 + Fe^{3+}}\]  ....(ii)

\[\ce{FeSO4 + MnO_4^- -> Mn^{2+} + CO2 + Fe^{3+}}\]   ...(iii)

Change in oxidation number of Mn is 5. Total change in oxidation in the above (i), (ii), (iii) equations are +3, +6, +1 respectively.

∴ No. of equivalent KMnO₄ = Total change in oxidation numbers

∴  n × 5 = 1 × 3 + 1 × 6 + 1 × 1

∴  n × 5 = 3 + 6 + 1

∴  n × 5 = 10

∴  n = `10/5`

∴  n = 2