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Question #44760
The Question
A galvanic concentration cell at is constructed as follows:
The concentrations and are determined by the following kinetic data:
- A bimolecular elementary reaction has a pre-exponential factor and an activation energy . The concentration is numerically equal to its rate constant when expressed in units of .
- A separate reaction follows order kinetics. Let be its rate constant in units of and be its rate constant in units of . Given the ratio , the concentration is numerically equal to .
Given and at , calculate the electromotive force () of the cell.
Options
- A.
0.472 V
- B.
0.826 V
- C.
0.708 V
- D.
0.531 V
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
Concentration Cells|Units of Rate Constant (k)|Collision Frequency vs. Effective Collisions|Electrode Potential Dependencies
Why This Question Is Tricky
Common Mistakes
This problem tests the intersection of electrochemistry and chemical kinetics through rigorous dimensional analysis.
The primary trap lies in converting macroscopic rate constant units (L/mol/s) to microscopic collision frequency units (cm^3/molecule/s), requiring correct application of Avogadro's number and volume conversions (students often divide by 10^3 instead of multiplying).
A secondary trap involves deriving the reaction order from the ratio of rate constants in different concentration units, testing the general unit formula (mol/L)^(1-n) s^-1.
Failing to account for the (1-n) exponent correctly leads to incorrect reaction orders and subsequently wrong cell potentials.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Electrochemistry - Class 12 |
| Concept | Concentration Cells |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |