Question

For the electrochemical cell,
$M|M^{+}||X^{-}|X,E^{\circ }\left(M^{+}/M\right)=0.44V$ and $E^{\circ }\left(X/X^{-}\right)=0.33V$ From this data, one can deduce that

• A. $M+X\to M^{+}+X^{-}$ is the spontaneous reaction
• B. $M^{+}+X^{-}\to M+X^{-}$ is the spontaneous reaction
• C. $E_{cell}=0.77V$
• D. $E_{cell}=-0.77V$

Answer 1

Answer: (B)

$M|M^{+}||X|X^{-}$, Cell reaction should be
$M+X\to M^{+}+X^{-}$
$E_{\text{cell}}^{\circ }=E_{\text{cathode}}^{\circ }-E_{\text{anode}}^{\circ }=0.33-0.44=-0.11V$
$\therefore$ Reverse cell reaction should be spontaneous i.e.
$M^{+}+X^{-}\to M+X$