For the given cell Fe 2+ ( eq )+ Ag + ( aq ) rightarrow Fe 3+ ( aq )+ Ag ( s ) The standard cell potential of the above reaction is Given : Ag + + e - rightarrow Ag E 0 = xV Fe 2+ +2 e - rightarrow Fe E 0 =y V Fe 3+ +3 e - rightarrow Fe E 0 = zV

Chemistry · Electrochemistry

JEE Main 2025 — 24 January, Morning Shift — Question 26

For the given cell

$\mathrm{Fe}^{2+}(\mathrm{eq})+\mathrm{Ag}^{+}(\mathrm{aq}) \rightarrow \mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s})$

The standard cell potential of the above reaction is Given :

$\mathrm{Ag}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Ag}$

$\mathrm{E}^{0}=\mathrm{xV}$

$\mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe}$

$E^{0}=y V$

$\mathrm{Fe}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe}$

$\mathrm{E}^{0}=\mathrm{zV}$

$\quad \mathrm{Fe}^{2+}(\mathrm{aq})+\mathrm{Ag}^{+}(\mathrm{aq}) \rightarrow \mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s})$

$\Delta \mathrm{G}_{3}^{0}=\Delta \mathrm{G}_{1}^{0}+\Delta \mathrm{G}_{2}^{0}$

$-3 \mathrm{~F}(-\mathrm{z})=-2 \mathrm{~F}(-\mathrm{y})+\Delta \mathrm{G}_{2}{ }^{0}$

$\Delta \mathrm{G}_{2}^{0}=3 \mathrm{Fz}-2 \mathrm{Fy}$

Also $\Delta \mathrm{G}_{2}^{0}=-\mathrm{nFE}_{\mathrm{Fe}^{+2} / \mathrm{Fe}^{+3}}^{0}$

$3 \mathrm{Fz}-2 \mathrm{Fy}=-1 \mathrm{~F}\left(\mathrm{E}_{\mathrm{Fe}^{+2} / \mathrm{Fe}^{+3}}^{0}\right)$

$\mathrm{E}_{\mathrm{Fe}^{+2} / \mathrm{Fe}^{+3}}^{0}=2 \mathrm{y}-3 \mathrm{z}$

$\mathrm{E}_{\text {Cell }}^{0}$ for reaction will be

$\mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{0}+\mathrm{E}_{\mathrm{Fe}^{+2} / \mathrm{Fe}^{+3}}^{0}$

$=x+2 y-3 z$

Answer key and solution verified before publishing.

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