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For a reaction Zn^(+2) + 2e^(-) rarr Zn,...

For a reaction `Zn^(+2) + 2e^(-) rarr Zn, E^(@) = -0.76V` which of the following statement is true? (E = Electrode potential)

A

E depends upon temperature

B

E changes when Zn plate is made bigger in size

C

E becomes double if equation is multiplied by2

D

`Zn^(+2)` can be reduced to Zn by `H_(2)` gas

Text Solution

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The correct Answer is:
To determine which statement is true regarding the given reaction \( \text{Zn}^{2+} + 2e^- \rightarrow \text{Zn} \) with an electrode potential \( E^\circ = -0.76 \, \text{V} \), we can analyze the properties of electrode potentials and their implications. ### Step-by-Step Solution: 1. **Understanding Electrode Potential**: The standard electrode potential \( E^\circ \) is a measure of the tendency of a chemical species to be reduced. A negative value indicates that the species is less likely to gain electrons compared to the standard hydrogen electrode (SHE). 2. **Identifying the Reaction**: The reaction given is the reduction of zinc ions to solid zinc. The half-reaction shows that zinc ions gain electrons to form solid zinc. 3. **Analyzing the Statements**: We need to evaluate the truth of the following statements: - **Statement 1**: \( E \) depends upon temperature. - **Statement 2**: \( E \) changes with the size of the zinc plate. - **Statement 3**: \( E \) becomes double if the equation is multiplied by 2. - **Statement 4**: \( \text{Zn}^{2+} \) can be reduced to Zn by \( \text{H}_2 \) (hydrogen gas). 4. **Evaluating Each Statement**: - **Statement 1**: True. The electrode potential can change with temperature as described by the Nernst equation. - **Statement 2**: False. The electrode potential is an intensive property and does not depend on the size of the electrode. - **Statement 3**: False. The electrode potential does not change if the stoichiometric coefficients of the reaction are multiplied; it remains an intensive property. - **Statement 4**: False. Zinc has a lower standard reduction potential than hydrogen, meaning zinc cannot be reduced by hydrogen. 5. **Conclusion**: The only true statement is that \( E \) depends upon temperature. ### Final Answer: **The true statement is: \( E \) depends upon temperature.**
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