Question

In which of the following Galvanic cells, emf is maximum? (Given: \( E^\circ_{\text{Mg}} = -2.36 \, V \) and \( E^\circ_{\text{Cl}_2/\text{Cl}^-} = +1.36 \, V \))

• A. Mg | Mg\(^{2+} \) (1 M) || 2Cl\(^{1-}\) (1 M) | Cl\(_2\) (1 atm), Pt
• B. Mg | Mg\(^{2+} \) (0.01 M) || 2Cl\(^{1-}\) (1 M) | Cl\(_2\) (1 atm), Pt
• C. Mg | Mg\(^{2+} \) (1 M) || 2Cl\(^{1-}\) (0.01 M) | Cl\(_2\) (1 atm), Pt
• D. Mg | Mg\(^{2+} \) (0.01 M) || 2Cl\(^{1-}\) (0.01 M) | Cl\(_2\) (1 atm), Pt

Hint:

For calculating emf, ensure to check the values at the cathode and anode to get the correct sign for emf.

Answer 1

The Correct Option is D

The emf of a Galvanic cell is given by: \[ \text{emf} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \] We calculate emf for each of the given options: \[ \text{Option 1: } E_{\text{cell}} = 1.36 - (-2.36) = 3.72 \, \text{V} \] \[ \text{Option 2: } E_{\text{cell}} = 1.36 - (-2.36) = 3.72 \, \text{V} \] \[ \text{Option 3: } E_{\text{cell}} = 1.36 - (-2.36) = 3.72 \, \text{V} \] \[ \text{Option 4: } E_{\text{cell}} = 1.36 - (-2.36) = 3.72 \, \text{V} \] The maximum emf is found for option 4.