Q. The standard reduction potential for ${Fe}^{2 +}/Fe\$and$\ {Sn}^{2 +}/Sn$ electrodes are – 0.44 and – 0.14 V respectively. For the given cell reaction, ${Fe}^{2 +} + Sn \rightarrow Fe + {Sn}^{2 +},$ the standard emf is
A) 0.42 V
B) $- \ 0.42$ V
C) $- \ 0.30$ V
D) $- \ 1.10$ V
Explanation
(c)
For the cell reaction, Fe acts as cathode and Sn as anode
Hence,
$E_{cell}^{{^\circ}} = E_{cathode}^{{^\circ}} - E_{anode}^{{^\circ}}$
$\ = - 0.44 - ( - 0.14) = - 0.30\ V$
The negative emf suggests that the reaction goes spontaneously in reversed direction
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.