Question

Which of the following reactions correctly represents a Daniell Cell?

• A. \( \text{Zn}(aq) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(aq) \)
• B. \( \text{ZnSO}_4(s) + \text{Cu} \rightarrow \text{CuSO}_4(aq) + \text{Zn}(aq) \)
• C. \( \text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s) \)
• D. \( \text{ZnSO}_4(aq) + \text{Cu} \rightarrow \text{CuSO}_4(aq) + \text{Zn}(s) \)

Hint:

In a Daniell cell, zinc undergoes oxidation to form Zn\(^{2+}\), while copper ions are reduced to form solid copper at the cathode.

Answer 1

The Correct Option is C

Step 1: Daniell Cell Overview.
A Daniell cell is an electrochemical cell that consists of a zinc electrode in a zinc sulfate solution and a copper electrode in a copper sulfate solution. The overall reaction in a Daniell cell is: \[ \text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s) \] In this reaction, zinc undergoes oxidation at the anode (losing electrons) and copper ions undergo reduction at the cathode (gaining electrons).

Step 2: Analysis of options.
- (1) \( \text{Zn}(aq) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(aq) \): This is incorrect as the zinc is solid, not in the aqueous form.
- (2) \( \text{ZnSO}_4(s) + \text{Cu} \rightarrow \text{CuSO}_4(aq) + \text{Zn}(aq) \): This is incorrect as it does not represent a Daniell cell and involves incorrect states of matter.
- (3) \( \text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s) \): This is correct and represents the actual Daniell cell reaction.
- (4) \( \text{ZnSO}_4(aq) + \text{Cu} \rightarrow \text{CuSO}_4(aq) + \text{Zn}(s) \): This is incorrect and does not represent a Daniell cell.

Step 3: Conclusion.
Thus, the correct reaction for a Daniell cell is option (3): \[ \text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s) \]