Some standard electrode potentials are given:<br>Fe2+ + 2e– Fe; E° = –0.440 V<br>Fe3+ + 3e– Fe; E° = — Electrochemistry Chemistry Question

💡 Solution & Explanation

$\Delta G_1^\circ (Fe^{2+} \rightarrow Fe) = -2F(-0.440) = +0.880F$. $\Delta G_2^\circ (Fe^{3+} \rightarrow Fe) = -3F(-0.036) = +0.108F$. The target reaction $(Fe^{3+} \rightarrow Fe^{2+})$ is $(Fe^{3+} \rightarrow Fe) - (Fe^{2+} \rightarrow Fe)$. $\Delta G^\circ = 0.108F - 0.880F = -0.772F$. Since $\Delta G^\circ = -1FE^\circ$, $E^\circ = +0.772$ V.