Question

For hydrogen - oxygen fuel cell at one $atm$ and $298\, K$ $H_2(g)+\frac {1}{2} O_2(g) \to H_2O_{(l)} ; \Delta G^\circ=-240\, kJ$ $E^\circ$ for the cell is approximately, (Given $F \,= \,96,500 \,C$)

• A. $1.25 \,V$
• B. $1.26 \,V$
• C. $2.48\, V$
• D. $2.5\, V$

Answer 1

Answer: (A)

$1.25 \,V$

Answer 2

From $\Delta G^{\circ}=-n F E^{\circ}$

where, $n=$ number of moles of electrons

transferred $=2$
$\Rightarrow F=96500\, C$
$\Delta G^{\circ}=-240\, kJ =-240 \times 1000\, J$
$\therefore E^{\circ}=\frac{-240000}{-2 \times 96500}=1.24\, V$