Question

KMnO\(_4\) oxidises hydrogen sulphide in acidic medium. The number of moles of KMnO\(_4\) which react with one mole of hydrogen sulphide is

• A. \( 2 \)
• B. \( 4 \)
• C. \( 0.4 \)
• D. \( 2.5 \)

Hint:

Always balance redox reactions using oxidation numbers or half-reaction method to get correct stoichiometric ratios.

Answer 1

The Correct Option is C

Explanation:

In acidic medium, the redox reaction between potassium permanganate and hydrogen sulphide is:

\[ 2KMnO_4 + 5H_2S + 3H_2SO_4 \rightarrow 2MnSO_4 + 5S + 8H_2O + K_2SO_4 \]

From the balanced reaction, 2 moles of KMnO\(_4\) react with 5 moles of H\(_2\)S.

So, for 1 mole of H\(_2\)S, the required moles of KMnO\(_4\) = \( \frac{2}{5} = 0.4 \)

Final Answer:

0.4