AIIMS2018Chemistry-Electrochemistry

AIIMS 2018 Chemistry Nernst Equation MCQ Question

Type: MCQ-numerical-Medium-Class 12

For hydrogen-oxygen fuel cell, the cell reaction is

2H2(g)+O2(g)2H2O(l)2\text{H}_2(\text{g}) + \text{O}_2(\text{g}) \rightarrow 2\text{H}_2\text{O}(\text{l})

If ΔGf(H2O)=237.2 kJmol1\Delta G_f^\circ(\text{H}_2\text{O}) = -237.2 \text{ kJmol}^{-1}, then emf of this cell is

A

+2.46 V

B

-2.46 V

C

+1.23 V

D

-1.23 V

Correct Answer

Option C

Detailed Explanation

The calculation of the standard electromotive force (E°) using the equation E° = -ΔG°/nF yields a value of 1.23 V, which is consistent with the expected theoretical value for the electrochemical reaction involving the reduction of CO₂ to carbohydrates. Option C is correct as it accurately reflects this calculated value, while the other options are not applicable or do not provide relevant information pertaining to the question. Understanding the relationship between Gibbs free energy (ΔG°), the number of electrons transferred (n), and Faraday's constant (F) is crucial for interpreting electrochemical cell behavior.

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