Question

Efficiency of the following cells is 84%.

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

Then the standard electrode potential of the cell will be

• A. 1.20 V
• B. 2.40 V
• C. 1.10 V
• D. 1.24 V

Answer 1

Answer: (D)

Efficiency $=\frac{\Delta G ^\circ }{\Delta H ^\circ }=\frac{- n F E ^\circ }{\Delta H ^\circ }$

$0.84=\frac{- 2 \times E ^\circ \times 96500}{- 285 \times 1000}$

$E^\circ =+1.24V$ .