Q. The cell reaction of Acell is $Mg\ (s)\ + \ {Cu}^{2 +}\ (aq) \longrightarrow \ Cu\ (s)\ + \ {Mg}^{2 +}\ (aq)\ .\$ If the standard reduction potentials of Mg and Cu are – 2.37 and + 0.34 V respectively. The emf of the cell is
A) 2.03 V
B) -2.03 V
C) +2.71 V
D) -2.71 V
Explanation
(c)
$Mg\ \rightarrow \ {Mg}^{2 +}\ \ + \ {2e}^{-}\ \ \ \ \ \ (at\ anode)$
${Cu}^{2 +}\ + \ {2e}^{-}\ \rightarrow \ Cu\ \ \ \ \ \ (at\ cathode)$
$E_{cell}^{{^\circ}}\ = \ E_{cathode}^{{^\circ}}\ - \ E_{anode}^{{^\circ}}$
= + 0.34 – (- 2.37)
= + 2.71 V
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.