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Question #44049
The Question
Consider a galvanic cell operating at with the following balanced cell reaction:
The standard cell potential at is . The temperature coefficient of the standard cell potential at constant pressure is .
Assuming that the standard enthalpy () and standard entropy () of the reaction are independent of temperature, determine the standard enthalpy of the reaction at and the temperature () at which the cell reaction reverses its direction of spontaneity under standard conditions.
(Given: Faraday's constant )
Options
- A.
,
- B.
,
- C.
,
- D.
,
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Mechanism_Trap
Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.
Concepts Behind This Question
Gibbs-Helmholtz Equation|Gibbs Energy and Spontaneity|Corrosion as Electrochemical Process
Why This Question Is Tricky
Common Mistakes
This problem tests the integration of electrochemistry with chemical thermodynamics via the Gibbs-Helmholtz equation.
The primary trap (Option B) is the assumption that , which ignores the significant entropic contribution derived from the temperature coefficient of the cell.
A secondary trap (Option C) is forgetting the stoichiometric number of electrons transferred () in the Nernstian derivation of entropy.
The problem forces students to recognize that a spontaneous reaction at room temperature can become non-spontaneous at higher temperatures if the entropy change is negative, physically manifested as a negative temperature coefficient of the cell potential.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Thermodynamics - Class 11 Part 1 |
| Concept | Gibbs-Helmholtz Equation |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |