Question

For a Galvanic cell consisting zinc electrode and standard hydrogen electrode,
\( \text{E}^\circ(\text{Zn}^{+2}_{(\text{aq}) \mid \text{Zn}_{(\text{s})}) = -0.76 \text{ V} \)}
Identify the reaction that takes place at positive electrode during working of cell?

• A. \( \text{Zn}_{(\text{s})} \rightarrow \text{Zn}^{+2}_{(\text{aq})} + 2\text{e}^- \)
• B. \( \text{Zn}^{+2}_{(\text{aq})} + 2\text{e}^- \rightarrow \text{Zn}_{(\text{s})} \)
• C. \( \text{H}_{2(\text{g})} \rightarrow 2\text{H}^+_{(\text{g})} + 2\text{e}^- \)
• D. \( 2\text{H}^+_{(\text{g})} + 2\text{e}^- \rightarrow \text{H}_{2(\text{g})} \)

Hint:

Anode = Negative (Oxidation); Cathode = Positive (Reduction) in a Galvanic cell.

Answer 1

The Correct Option is D

Step 1: Concept
In a Galvanic cell, the positive electrode is the cathode, where reduction occurs.

Step 2: Meaning
Reduction is the gain of electrons. The electrode with the higher reduction potential acts as the cathode.

Step 3: Analysis
\( \text{E}^\circ_{\text{Zn}} = -0.76 \text{ V} \) and \( \text{E}^\circ_{\text{H}} = 0.00 \text{ V} \). Since $0.00 > -0.76$, the Hydrogen electrode is the cathode (positive electrode).

Step 4: Conclusion
The reduction of $\text{H}^+$ ions to $\text{H}_2$ gas occurs at the positive electrode. Final Answer: (D)