Question

In order to oxidize a mixture of one mole of each of FeC₂O₄, Fe₂ (C₂O₄)₃, FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is:
1. 2
2. 1
3. 3
4. 1.5

Answer 1

Correct Answer - Option 1 : 2

Concept:

The oxidation reactions of the given are:

FeC₂O₄ ⟶ Fe⁺³ + CO₂

Fe₂(C₂O₄)₃ ⟶ CO₂

Fe₂(SO₄)₃ ⟶ No oxidation

FeSO₄ ⟶ Fe⁺³

Eq(KMnO₄) = Eq(FeC₂ O₄) + Eq(Fe₂(C₂O₄)₃) + Eq(FeSO₄)

Calculation:

The formula of equivalents is:

Equivalents = Mole × n-factor

The n-factor of KMnO₄ in acidic medium is 5.

The n-factor of FeC₂O₄ in acidic medium is 3.

The n-factor of Fe₂(C₂O₄ )₃ in acidic medium is 6.

The n-factor of FeSO₄ in acidic medium is 1.

On substituting the equivalents formula with n-factor values in the given compounds, we get,

(x × 5) = (Moles × 3) + (Moles × 6) + (Moles × 1)

From question, we know that the compounds which are need to be oxidised is of one mole. So, we can substitute 1 in the mole place.

⇒ (x × 5) = (1 × 3) + (1 × 6) + (1 × 1)

⇒ x × 5 = 10

\(\Rightarrow x = \frac{{10}}{5}\)

∴ x = 2