Question

Which of the following net cell reaction takes place in a galvanic cell containing copper electrode and standard hydrogen electrode? $E^{\circ}(Cu^{2+}|Cu) = +0.34 V$

• A. $Cu_{(s)} + 2H_{(aq)}^{+} \rightarrow Cu_{(aq)}^{2+} + H_{2(g)}$
• B. $H_{2(g)} + Cu_{(aq)}^{2+} \rightarrow 2H_{(aq)}^{+} + Cu_{(s)}$
• C. $Cu_{(s)} + H_{2(g)} \rightarrow Cu_{(aq)}^{2+} + 2H_{(aq)}^{+}$
• D. $Cu_{(aq)}^{2+} + 2H_{(aq)}^{+} \rightarrow Cu_{(s)} + H_{2(g)}$

Hint:

Higher $E^{\circ}$ goes at the cathode (reduction).

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
In a galvanic cell, the half-cell with a higher reduction potential acts as the cathode (reduction), and the one with a lower potential acts as the anode (oxidation).

Step 3: Detailed Explanation:
- Standard reduction potential of SHE: $E^\circ (\text{H}^+ \mid \text{H}_2) = 0.00 \text{ V}$.
- Given: $E^\circ (\text{Cu}^{2+} \mid \text{Cu}) = +0.34 \text{ V}$.
Since $+0.34 \text{ V} > 0.00 \text{ V}$, Copper electrode acts as cathode and Hydrogen electrode acts as anode.
- At Anode (Oxidation): $\text{H}_{2(\text{g})} \longrightarrow 2\text{H}^{+}_{(\text{aq})} + 2\text{e}^-$
- At Cathode (Reduction): $\text{Cu}^{+2}_{(\text{aq})} + 2\text{e}^- \longrightarrow \text{Cu}_{(\text{s})}$
- Net reaction: $\text{H}_{2(\text{g})} + \text{Cu}^{+2}_{(\text{aq})} \longrightarrow 2\text{H}^{+}_{(\text{aq})} + \text{Cu}_{(\text{s})}$

Step 4: Final Answer:
The correct net reaction is Option B.