Collision theory and rates of reaction Quiz
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5 questions, one answer each
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1. Which change does NOT alter the proportion of collisions with energy ≥ Ea?
- A. Raising the temperature
- B. Adding a catalyst
- C. Doubling the concentration
- D. Lowering the temperature
2. Why does the rate of a reaction fall as it proceeds?
- A. The activation energy increases
- B. The temperature falls
- C. The concentration of reactant falls, so collisions are less frequent
- D. The particles lose energy
3. A reaction takes 25 s at one temperature and 50 s at a lower temperature. How does the rate at the higher temperature compare?
- A. Twice as fast
- B. Half as fast
- C. Four times as fast
- D. The same
4. A tangent to a curve at t = 0 passes through (0 s, 0 mol dm⁻³) and (50 s, 0.20 mol dm⁻³). What is the initial rate of formation of the product?
- A. 4.0 × 10⁻³ mol dm⁻³ s⁻¹
- B. 2.5 × 10² mol dm⁻³ s⁻¹
- C. 0.20 mol dm⁻³ s⁻¹
- D. 10 mol dm⁻³ s⁻¹
5. A student claims that crushing a solid makes particles collide with more energy. Which response is correct?
- A. Correct, because the particles are smaller
- B. Incorrect; crushing increases the surface area and so collision frequency, but not the energy of collisions
- C. Correct, because the activation energy falls
- D. Incorrect; crushing reduces the rate