R2.2 How fast? The rate of chemical change Quiz
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5 questions, one answer each
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1. Which change increases the rate mainly by increasing the proportion of collisions with E ≥ Ea at unchanged Ea?
- A. Increasing concentration
- B. Increasing temperature
- C. Grinding a solid into powder
- D. Increasing gas pressure
2. An exothermic reaction has Ea = 60 kJ mol⁻¹ and ΔH = −40 kJ mol⁻¹. What is Ea for the reverse reaction?
- A. 20 kJ mol⁻¹
- B. 40 kJ mol⁻¹
- C. 60 kJ mol⁻¹
- D. 100 kJ mol⁻¹
3. What happens to the area under a Maxwell–Boltzmann curve when the temperature of a fixed sample is raised?
- A. It increases
- B. It decreases
- C. It stays the same
- D. It doubles for every 10 K
4. Which statement about a catalyst is correct?
- A. It increases the kinetic energy of particles
- B. It makes ΔH more negative
- C. It lowers the activation energy of forward and reverse reactions
- D. It is used up in the reaction
5. 30.0 cm³ of gas is collected in 12 s. What is the mean rate?
- A. 0.40 cm³ s⁻¹
- B. 2.5 cm³ s⁻¹
- C. 360 cm³ s⁻¹
- D. 2.5 cm³ min⁻¹