Question

The efficiency of an hypothetical cell is about 84% which involves the following reaction :
$A\left(s\right)+B^{2+}\left(aq\right)\to A^{2+}\left(aq\right)+B\left(s\right):\Delta H=-285kJ$
Then, the standard electrode potential of the cell will be: (Assume as $\Delta S=0$)

• A. 1.2
• B. 2.40 V
• C. 1.10 V
• D. 1.24 V

Answer 1

The correct option is D 1.24 V

$A+B^{2+}\left(aq\right)\to A^{2+}\left(aq\right)+B\left(s\right)$ $\Delta H=-285kJ$

$\Delta G=\Delta H+T\Delta S$

$\Delta S=0$ $\Delta G=-nF{E}^o$

$\Delta G=\Delta H=-285$ $-285=-2\times 96487\times E^o$

$E^o=\frac{285\times {10}^3}{2\times 96487}=1.4769$

standard electrode potential = $1.47\times \frac{84}{100}=1.24V$

Option D is correct.