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Question #44069
The Question
The gas-phase reaction \ce{A(g) + 2B(g) <=> C(g)} has an equilibrium constant at . The activation energy for the forward uncatalyzed reaction is .
To improve the rate of product formation, a solid catalyst is introduced, which alters the reaction pathway to the following mechanism: Step 1: \ce{A(g) + B(g) <=> I(g)} (Fast equilibrium) Step 2: \ce{I(g) + B(g) <=> C(g)} (Slow, rate-determining step)
The catalyst lowers the activation energy of the forward reaction by . Assuming ideal gas behavior and that the concentration of the intermediate \ce{I(g)} is negligible at macroscopic equilibrium, what is the value of the equilibrium constant for the catalyzed reaction at ?
(Given: for pressure calculations, for energy calculations, and )
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
Relationship between Kp and Kc|Reaction Progress Coordinate
Why This Question Is Tricky
Common Mistakes
This problem tests the student's ability to distinguish between kinetic parameters (which change with mechanism) and thermodynamic parameters (which remain invariant).
The primary trap is the assumption that a catalyst, by lowering the activation energy or altering the reaction mechanism, changes the equilibrium constant.
Students often erroneously adjust using the Arrhenius factor (Option B), forgetting that the backward activation energy is lowered equally.
Additionally, the problem presents a multi-step mechanism to bait students into using the of the rate-determining step (Option C) rather than the overall macroscopic stoichiometry required for the relationship.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Equilibrium - Class 11 Part 1 |
| Concept | Relationship between Kp and Kc |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |