AIIMS 2018 Chemistry Nernst Equation MCQ Question
The standard EMF for the cell reaction, Zn + Cu²⁺ → Cu + Zn²⁺ is 1.1 volt at 25°C. The EMF for the cell reaction, when 0.1 M Cu²⁺ and 0.1M Zn²⁺ solutions are used, at 25°C is
1.10 V
0.10 V
−1.10 V
−0.110 V
Correct Answer
Detailed Explanation
The standard EMF (electromotive force) of the cell reaction Zn + Cu²⁺ → Cu + Zn²⁺ is given as 1.1 V, which reflects the potential difference under standard conditions (1 M concentrations). Since both Cu²⁺ and Zn²⁺ are at 0.1 M, the Nernst equation can be applied, but with equal concentrations, the reaction quotient (Q) remains 1, resulting in no change to the standard EMF. Therefore, the EMF remains 1.10 V.
Options B (0.10 V), C (−1.10 V), and D (−0.110 V) are incorrect as they suggest a significant deviation from the standard EMF, which does not occur under these specific concentration conditions.
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