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: Concept
Reaction occurs such that the species with higher reduction potential gets reduced (Cathode).

Step 2: Analysis
- $E^{\circ}(Cu^{2+}/Cu) = +0.34 V$ - $E^{\circ}(H^+/H_2) = 0.00 V$ - Since $0.34 > 0.00$, $Cu^{2+}$ will be reduced and $H_2$ will be oxidized.

Step 3: Equation
Oxidation: $H_2 \rightarrow 2H^+ + 2e^-$
Reduction: $Cu^{2+} + 2e^- \rightarrow Cu$

Step 4: Conclusion
Net: $H_2 + Cu^{2+} \rightarrow 2H^+ + Cu$. Final Answer: (B)