Q. Which of the following will form a cell with the highest voltage?
A) $0.1\ M\ {Ag}^{+},\ 2\ M\ {Co}^{2 +}$
B) $2\ M\ {Ag}^{+},\ 2\ M\ {Co}^{2 +}$
C) $1\ M\ {Ag}^{+},1\ M\ {Co}^{2 +}$
D) $2\ M\ {Ag}^{+},0.1\ M\ {Co}^{2 +}$
Explanation
(d)
Cobalt is anode, $ie,$ oxidation takes place on cobalt electrode $ie,$ cell reaction is
$Co + 2{Ag}^{+} \rightarrow {Co}^{2 +} + 2Ag$
$E_{cell} = E_{cell}^{{^\circ}} - \frac{RT}{nF}\ln\frac{\left\lbrack {Co}^{2 +} \right\rbrack}{\left\lbrack {Ag}^{+} \right\rbrack^{2}}$
Thus, less is the factor $\frac{\left\lbrack {Co}^{2 +} \right\rbrack}{\lbrack{Ag}^{+}\rbrack},$ greater is the $E_{cell}^{{^\circ}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.