Question

Calculate emf of the following cell: \[ \text{Zn (s)} | \text{Zn}^{2+} (0.1 M) || \text{Sn}^{2+} (0.001 M) | \text{Sn (s)} \] Given: \[ E^\circ_{\text{Zn}^{2+}/\text{Zn}} = -0.76 \, \text{V}, \quad E^\circ_{\text{Sn}^{2+}/\text{Sn}} = -0.14 \, \text{V} \] \[ [\log 10 = 1] \]

Hint:

- The Nernst equation helps calculate the emf of electrochemical cells by considering the concentrations of the ions involved. - The formula involves standard reduction potentials and logarithmic terms for concentration ratios.

Answer 1

The equation for the emf of the cell is: \[ E_{\text{cell}} = \left( E^\circ_{\text{c}} - E^\circ_{\text{a}} \right) - \frac{0.059}{2} \log \frac{[\text{Zn}^{2+}]}{[\text{Sn}^{2+}]} \] Substituting the given values: \[ E_{\text{cell}} = \left[ (-0.14) - (-0.76) \right] - \frac{0.059}{2} \log \frac{0.1}{0.001} \] \[ E_{\text{cell}} = +0.62 - 0.059 \] \[ E_{\text{cell}} = (0.62 - 0.059 ) \, \text{V} = 0.561 \, \text{V} \]