Practicing Success

Target Exam

CUET

Subject

Chemistry

Chapter

Physical: Electro Chemistry

Question:

Statement I: Zinc displaces copper from copper sulphate solution

Statement II: The E° value of zinc is –0.76 V and that of copper is +0.34

Options:

Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

Both Statement I and Statement II are correct and Statement II is not a correct explanation of Statement I

Statement I is correct but Statement II is false

Statement I is false but Statement II is correct

Correct Answer:

Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

Explanation:

The correct answer is 1. Both Statement I and Statement II are correct, and Statement II is the correct explanation of Statement I.
Statement I: Zinc displaces copper from copper sulphate solution.
This statement is correct. The activity series of metals determines the order in which metals can displace each other from their salts in solution. In this case, zinc has higher reactivity than copper and is higher in the activity series. When zinc is added to copper sulfate solution, zinc displaces copper ions (Cu²⁺) from the solution, forming zinc sulfate (ZnSO₄) and depositing solid copper metal.
Statement II: The E° value of zinc is -0.76 V, and that of copper is +0.34 V.
This statement is also correct. The E° value (standard reduction potential) of a half-cell reaction measures the tendency of the species to undergo reduction (gain electrons) compared to the standard hydrogen electrode (SHE). A more positive E° value indicates a higher tendency to undergo reduction, while a more negative E° value indicates a lower tendency to undergo reduction.
In this case, zinc has an E° value of -0.76 V, which means that the half-cell reaction \(Zn^{2+} + 2e^- \rightarrow Zn\) has a higher tendency to occur in the reduction direction (on the left side) compared to the SHE. On the other hand, copper has an E° value of +0.34 V, indicating that the half-cell reaction \(Cu^{2+} + 2e^- \rightarrow Cu\) has a lower tendency to occur in the reduction direction (on the left side) compared to the SHE.

The explanation (Statement II) is that because zinc has a more negative E° value than copper, it has a higher tendency to undergo reduction. Hence, when zinc is added to copper sulfate solution, it displaces copper ions, and solid copper is deposited, as explained in Statement I.

In conclusion, both statements are correct, and Statement II provides the correct explanation for why zinc displaces copper from copper sulfate solution. The correct answer is 1.