Q. Consider the following $E{^\circ}$ values $E{^\circ}_{{Fe}^{3 +}/{Fe}^{2 +}} = + 0.77\ V$ $E{^\circ}_{{Sn}^{2 +}/Sn} = - \ 0.14\ V$ Under standard conditions, the potential for the reaction $Sn(s) + 2{Fe}^{3 +}(aq) \rightarrow 2{Fe}^{2 +}(aq) + {Sn}^{2 +}(aq)$ is
A) $- \ 0.91\ V$
B) $+ \ 0.91\ V$
C) $- \ 0.41\ V$
D) $+ \ 0.41\ V$
Explanation
(b)
For, $Sn(s) + \ 2{Fe}^{3 +}(aq) \rightarrow 2{Fe}^{2 +}(aq) + {Sn}^{2 +}(aq)$
$E_{cell}^{{^\circ}} = E_{Sn/{Sn}^{2 +}}^{{^\circ}} + E_{{Fe}^{3 +}/{Fe}^{2 +}}^{{^\circ}}$
$= (0.14) + (0.77) = 0.91\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.