Question

Given that the standard reduction potentials for $M^{+}/M$ and $N^{+}/N$ electrodes at $298K$ are $0.52V$ and $0.25V$ respectively. Which of the following is correct in respect of the following electrochemical cell?
$M|M^{+}||N^{+}|N$

• A. The overall cell reaction is a spontaneous reaction
• B. The standard EMF of the cell is $-0.27V$
• C. The standard EMF of the cell is $0.77V$
• D. The standard EMF of the cell is $-0.77V$
• E. The standard EMF of the cell is $0.27V$

Answer 1

The correct option is B The standard EMF of the cell is $-0.27V$

$E_{cell}^o=E_{cathode}^o-E_{anode}^o$
$=E_{\left(N^{+}/N\right)}^o-E_{\left(M^{+}/M\right)}^o$
$=(0.25-0.52)=-0.27V$
Since, $E_{cell}^o$ is negative, the cell reaction is non-spontaneous.