Q93 · CSIR NET Chemistry, December 2011
Paper: CSIR NET December 2011 · Subject: Physical Chemistry · Chapter: Electrochemistry · Topic: Nernst Cells · Marks: 2 · Difficulty: Medium
The standard electrode potentials $(\mathrm{E}^{\circ})$ of $\mathrm{Fe}^{3+}/\mathrm{Fe}^{2+}$ and $\mathrm{Fe}^{2+}/\mathrm{Fe}$ electrodes are + 0.77V and -0.44 V respectively at 300 K. The $\mathrm{E}^{\circ}$ of $\mathrm{Fe}^{3+}/\mathrm{Fe}$ electrode at the same temperature is
(a)1.21 V
(b)0.33 V
(c)-0.11V
(d)-0.04 V
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
E°(Fe³⁺/Fe) = [E°(Fe³⁺/Fe²⁺) + 2E°(Fe²⁺/Fe)]/3 = (0.77 − 0.88)/3 = −0.04 V.
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