Consider the following cell $\left.\mathrm{Zn}_{(\mathrm{s})} \mid…
Consider the following cell
$\left.\mathrm{Zn}_{(\mathrm{s})} \mid \mathrm{Zn}_{(\mathrm{IM})}^{2+}\right)\left|\mathrm{KCl}_{(\mathrm{sat})}\right| \underset{\text { (paste) }}{\mathrm{Hg}_2 \mathrm{Cl}_2} \mid \mathrm{Hg}$
$\mathrm{E}^{\circ}$ cell $=1.007 \mathrm{~V}$ and $\mathrm{E}^{\circ}$ calomel $=0.242 \mathrm{~V}$ What is the standard potential of Zn ?
$\quad-0.765 \mathrm{~V}$
0.765 V
-1.247 V
1.247 V
Solution
The standard cell potential is given by
$\begin{aligned}
E_{\text {cell }}^o & =E_{\text {cathode }}^o-E_{\text {anode }}^o \\
E_{\text {cell }}^o & =E_{\text {Calomel }}^o-E_{Z \text { n }}^o \\
& =(0.242 \cdot \mathrm{~V})-1.007 \mathrm{~V} \\
& =-0.765 \mathrm{~V}
\end{aligned}$