3.92 g of ferrous ammonium sulphate are dissolved in 100 mL water. 20 mL of this solution requires 18 mL of potassium permanganate during titration for complete oxidation. The weight of KMnO 4 present in one litre of the solution is

Question

3.92 g of ferrous ammonium sulphate are dissolved in 100 mL water. 20 mL of this solution requires 18 mL of potassium permanganate during titration for complete oxidation. The weight of KMnO 4 present in one litre of the solution is (A) 34.76 g (B) 12.38 g (C) 1.238 g (D) 3.51 g

Tardigrade Admin · Accepted Answer

The redox reaction involving the oxidation of

F e^{2 +}

(from ferrous ammonium sulphate) is

M n O_{4}^{-} + 5 F e^{2 +} + 8 H^{+} ⟶ 5 F e^{3 +} + M n^{2 +} + 4 H_{2} O

Mol. wt. of ferrous ammonium sulphate,

(N H_{4})_{2} S O_{4} \cdot F e S O_{4} \cdot 6 H_{2} O = 392

∴

Molarity of

(N H_{4})_{2} S O_{4} \cdot F e S O_{4} \cdot 6 H_{2} O

= \frac{W t}{Mol. wt.} \times \frac{1000}{Volume} = \frac{3.92}{392} \times \frac{1000}{100} = 0.1

Applying molarity equation,

\frac{M _{1} V _{1}}{n _{1}} (Ferrous amm. sulphate) = \frac{M _{2} V _{2}}{n _{2}} (K M n O_{4})

or \frac{0 \cdot 1 \times 20}{5} = \frac{M _{2} \times 18}{1} or M_{2} = \frac{0 \cdot 1 \times 20}{5 \times 18} = \frac{1}{45}

Amount of

K M n O_{4}

present in one litre

= Molarity \times Mol. wt. = \frac{1}{45} \times 158 = 3 \cdot 51 g

Q. $3.92 g$ of ferrous ammonium sulphate are dissolved in $100 m L$ water. $20 m L$ of this solution requires $18 m L$ of potassium permanganate during titration for complete oxidation. The weight of $K M n O_{4}$ present in one litre of the solution is

$34.76 g$

$12.38 g$

$1.238 g$

$3.51 g$

Q. 3.92g of ferrous ammonium sulphate are dissolved in 100mL water. 20mL of this solution requires 18mL of potassium permanganate during titration for complete oxidation. The weight of KMnO4​ present in one litre of the solution is

34.76g

12.38g

1.238g

3.51g

Q. $3.92 g$ of ferrous ammonium sulphate are dissolved in $100 m L$ water. $20 m L$ of this solution requires $18 m L$ of potassium permanganate during titration for complete oxidation. The weight of $K M n O_{4}$ present in one litre of the solution is

$34.76 g$

$12.38 g$

$1.238 g$

$3.51 g$