Question

$MnO^{-}_{4} + 8H^{+} + 5e^{-} \to Mn^{2+} + 4H_{2}O$
If $H^{+}$ concentration is decreased from 1 M to $10^{-4}$ M at $25°C$,

• A. the potential decreases by 0.38 V with decrease in oxidising power
• B. the potential increases by 0.38 V with increase in oxidising power
• C. the potential decreases by 0.25 V with decreases in oxidising power
• D. the potential decreases by 0.38 V without affecting oxidising power

Answer 1

Answer: (A)

$\Delta E =\frac{0.059}{5}log \left[10^{-4}\right]^{8}=-0.378\, V$