Question

Find out the correct graph for the variation of \( E_{\text{cell}} \) with temperature.

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

For exothermic reactions in electrochemical cells, the cell potential typically decreases with an increase in temperature.

Answer 1

The Correct Option is A

Step 1: Understand the relationship between \( E_{\text{cell}} \) and temperature.
The cell potential \( E_{\text{cell}} \) for a galvanic cell is related to the temperature through the Nernst equation. Typically, for most electrochemical reactions, the cell potential decreases as temperature increases, especially when the reaction is exothermic. This behavior is in accordance with the Gibbs free energy equation: \[ \Delta G = -nFE_{\text{cell}} \] For exothermic reactions, an increase in temperature leads to a decrease in \( E_{\text{cell}} \).
Step 2: The relationship between \( E_{\text{cell}} \) and temperature.
At constant pressure, for reactions like the one in the question, the relationship is approximately linear. The graph showing a decrease in \( E_{\text{cell}} \) with temperature is a characteristic behavior for most electrochemical reactions. Thus, the correct graph is the one that shows a linear decrease of \( E_{\text{cell}} \) with increasing temperature.