Q. $E_{1},\ E_{2}$, and $E_{3}$ are the emfs of the following three galvanic cells respectively Zn (s) | ${Zn}^{2 +}$ (0.1 M) || ${Cu}^{2 +}$ (1 M) | Cu (s) Zn (s) | ${Zn}^{2 +}$ (1 M) || ${Cu}^{2 +}$ (1 M) | Cu (s) Zn (s) | ${Zn}^{2 +}$ (1 M) || ${Cu}^{2 +}$ (0.1 M) | Cu (s) Which one of the following is true?
A) $E_{2} > E_{1} > E_{3}$
B) $E_{1} > E_{2} > E_{3}$
C) $E_{3} > E_{1} > E_{2}$
D) $E_{3} > E_{2} > E_{1}$
Explanation
(d)
For the given cell,
$E_{cell} = \ E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}\log\frac{\lbrack{Zn}^{2 +}\rbrack}{\lbrack{Cu}^{2 +}\rbrack}$
$E_{1} = E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}\log\frac{1}{0.1}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \ E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}$
$E_{2} = E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}\log\frac{1}{1}$
$= \ E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}\ \times 0$
$= \ E_{cell}^{{^\circ}}\ \ \$
$E_{2} = E_{cell}^{{^\circ}} - \ \frac{0.0591}{2}\log\frac{0.1}{1}$
$= \ E_{cell}^{{^\circ}} + \ \frac{0.0591}{2}\$
∴ $\ E_{3}\ > \ \ E_{2}\ > \ \ E_{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.