Rate-determining step and reaction mechanisms Quiz
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5 questions, one answer each
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1. A reaction has rate = k[A]²[B]⁰. Which statement about the rate-determining step is correct?
- A. It contains one A and one B
- B. It contains two A and no B
- C. It contains one A only
- D. It contains two B
2. The steps of a mechanism are: Step 1 (slow) X + Y → Z; Step 2 (fast) Z + Y → P. What is the rate equation?
- A. rate = k[X][Y][Z]
- B. rate = k[X][Y]²
- C. rate = k[Z][Y]
- D. rate = k[X][Y]
3. In the mechanism above, which species is the intermediate?
- A. Z
- B. X
- C. Y
- D. P
4. What happens to the rate of a reaction if a catalyst speeds up only a fast step that follows the slow step?
- A. It increases greatly
- B. It decreases
- C. It barely changes
- D. It doubles exactly
5. A student writes a rate equation using the coefficients of the overall equation. Why may this be wrong?
- A. Coefficients are always the orders
- B. The orders come from the slow step in the mechanism and from experiment, not from the overall equation
- C. Rate equations cannot contain powers
- D. Intermediates must be included