Question

In an electrochemical cell, the standard electrode potential of Zn\(^{2+}\)/Zn is \(-0.76\, \text{V}\) and that of Cu\(^{2+}\)/Cu is \(+0.34\, \text{V}\). What is the standard EMF of the cell?

• A. 1.10 V
• B. -1.10 V
• C. 0.42 V
• D. -0.42 V

Hint:

Standard EMF of a cell is calculated as \( E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \). The more positive potential is the cathode.

Answer 1

The Correct Option is A

Step 1: Identify the cathode and anode.
In a galvanic cell, the electrode with higher (more positive) potential acts as cathode. \[ \begin{cases} E^\circ_{\mathrm{Cu}^{2+}/\mathrm{Cu}} = +0.34\, \mathrm{V} & \text{(Cathode)} \\ E^\circ_{\mathrm{Zn}^{2+}/\mathrm{Zn}} = -0.76\, \mathrm{V} & \text{(Anode)} \end{cases} \]
Step 2: Use the EMF formula. \[ E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} = 0.34 - (-0.76) = 1.10\, \text{V} \]