Question

For the electrochemical cell,
$M|M^{+}||X^{-}|X,E_{M^{+}/M}^o=0.44V$ and$E_{X/X^{-}}^o=0.33V$. 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

The correct option is B $M^{+}+X^{-}\to M+X$ is the spontaneous reaction

Given,
$E_{M^{+}/M}^o=0.44V;E_{X/X^{-}}^o=0.33V$
$E_{RP}^o$ for M > $E_{RP}^o$ for X
Thus, $M^{+}+e\to M;E_{M^{+}/M}^o=0.44V$
$X^{-}\to X+e;E_{X^{-}/X}^o=-0.33V$
$\therefore M^{+}+X^{-}\to M+X$
$E_{cell}^o=E_{O{P}_x}^o+E_{R{P}_M}^o=-0.33+0.44=0.11V$
As electrode potential of cell is positive so forward reaction is spontaneous.
Which is followed by $\Delta G^o=-nF{E}^o$