Question

In which solution, the oxidizing power of $KMnO_4$ will be greater.

• A. 0.01 M
• B. 0.001M $H_2SO_4$ solution

Answer 1

Answer: (A)

(a)

Answer 2

The oxidizing power of $KMnO_4$ in acidic medium depends on the concentration of $H^+$ ions as per the Nernst equation for the $MnO_4^-/Mn^{2+}$ redox couple. The reaction is $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$. A higher concentration of $H^+$ ions shifts the equilibrium to the right, increasing the reduction potential and thus the oxidizing power. Comparing the two given solutions, 0.01 M $H_2SO_4$ (0.02 M $H^+$) has a higher $H^+$ concentration than 0.001 M $H_2SO_4$ (0.002 M $H^+$). Therefore, the oxidizing power of $KMnO_4$ is greater in 0.01 M $H_2SO_4$.