What is the correct Nernst equation for the following cell? $Zn(s)|Zn^{2+}||Ag^+|Ag(s)$ |
$E_{cell}=E°_{cell}-\frac{RT}{F}\log\frac{[Ag^+]}{[Zn^{2+}]}$ $E_{cell}=E°_{cell}-\frac{2.303\,RT}{nF}\log\frac{[Zn^{2+}]}{[Ag^+]^2}$ $E_{cell}=E°_{cell}-\frac{2.303RT}{F}\log\frac{[Ag^+]}{[Zn^{2+}]}$ $E_{cell}=E°_{cell}-\frac{2.303\,RT}{nF}\log\frac{[Zn^{2+}]}{[Ag^+]}$ |
$E_{cell}=E°_{cell}-\frac{2.303\,RT}{nF}\log\frac{[Zn^{2+}]}{[Ag^+]^2}$ |
The correct answer is Option (2) → $E_{cell}=E°_{cell}-\frac{2.303\,RT}{nF}\log\frac{[Zn^{2+}]}{[Ag^+]^2}$ For the cell: $Zn(s) | Zn^{2+} || Ag^+ | Ag(s)$ Step 1: Write the cell reaction: $Zn(s) + 2 Ag^+ (aq) -> Zn^{2+} (aq) + 2 Ag(s)$
Step 2: General Nernst equation: $E_\text{cell} = E_\text{cell}^\circ - \frac{0.0591}{n} \log Q$ $Q = \frac{[Zn^{2+}]}{[Ag^+]^2} \quad \text{(products/reactants)}$ $E_\text{cell} = E_\text{cell}^\circ - \frac{0.0591}{2} \log \frac{[{Zn^{2+}}]}{[{Ag^+}]^2} = E_\text{cell}^\circ - \frac{0.0591}{2} \log [{Zn^{2+}}] + 0.0591 \log [{Ag^+}]$ Step 3: Compare with options $E_\text{cell} = E_\text{cell}^\circ - \frac{2.303 RT}{nF} \log \frac{[{Zn^{2+}}]}{[{Ag^+}]^2}$ |