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Question #44765
The Question
A lead storage battery operates at with the following overall discharge reaction:
The standard cell potential is . Initially, the bulk electrolyte concentrations are and . During a rapid discharge at a constant current of , severe concentration polarization occurs, causing the local surface concentrations at the electrodes to drop to and .
Given the activation overpotential and the internal resistance of the cell , calculate the actual terminal voltage () of the battery during this discharge.
(Assume at )
Options
- A.
1.85 \text{ V}
- B.
1.76 \text{ V}
- C.
1.61 \text{ V}
- D.
2.01 \text{ 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
Secondary Battery Discharge Cycles|Nernst Equation Concentration Dependence|Electrode Potential Dependencies
Why This Question Is Tricky
Common Mistakes
Students often mistakenly use bulk concentrations in the Nernst equation, ignoring that electrochemical reactions are interfacial phenomena.
During rapid discharge, the local concentration of reactants at the electrode surface depletes (Concentration Polarization), significantly altering the reaction quotient .
This problem tests the ability to bridge thermodynamic idealization with electrochemical kinetics by forcing the calculation of the true surface potential before applying kinetic losses (activation overpotential and Ohmic drop) to find the terminal voltage.
Failing to account for the 4th and 2nd power stoichiometric dependencies of and respectively, or using bulk values, leads to incorrect higher voltage estimates.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Electrochemistry - Class 12 |
| Concept | Secondary Battery Discharge Cycles |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |