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Question #44737
The Question
Consider the following electrochemical cell operating in a mixed aqueous-organic solvent at :
Due to the lower dielectric constant of the solvent, significant ion-pairing occurs, preventing complete dissociation. The observed Van't Hoff factors () for the and solutions are and , respectively.
Given standard reduction potentials: and .
Assume the activity coefficients of the free, un-paired ions are unity, and that ion-pairing is the sole reason for the deviation of from the ideal stoichiometric value. (Take )
What is the cell potential, ?
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Numerical_Precision
Improve calculation stamina and avoid rounding errors in high-stakes competitive examinations.
Concepts Behind This Question
Standard Electrode Potential Sign Conventions|Van’t Hoff Factor (i) Application|Reaction Progress Coordinate
Why This Question Is Tricky
Common Mistakes
This problem tests the deep-structure thermodynamic accuracy of the Nernst equation.
Students frequently fall into the trap of using the analytical (stoichiometric) concentration () directly in the reaction quotient , which incorrectly yields (Option B).
The 'Hidden Variable' is the non-ideal behavior caused by ion-pairing.
By providing the Van't Hoff factor, the student is required to extract the degree of dissociation () to find the true activity of the free electroactive ions.
Another common trap is multiplying the concentration directly by instead of , or inverting the anode/cathode ratio in the log term (Option C).
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Electrochemistry - Class 12 |
| Concept | Standard Electrode Potential Sign Conventions |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |