For the given cell Fe^{2+} (eq) + Ag^+ (aq) → Fe^{3+} (aq) + Ag(s) The standard cell potential of the above reaction

Question

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 :

\(\mathrm{Ag}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Ag}\quad \mathrm{E}^{0}=\mathrm{xV}\)

\(\mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad E^{0}=y V\)

\(\mathrm{Fe}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad\mathrm{E}^{0}=\mathrm{zV}\)

(1) \(x+y-z\)

(2) \(x+2 y-3 z\)

(3) \(y-2 x\)

(4) \(x+2 y\)

Answer 1

Correct option is : (2) x + 2y – 3z

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

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

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

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

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

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

\( =x+2 y-3 z\)