R2.2 How fast? The rate of chemical change Quiz
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5 questions, one answer each
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1. Rate = k[X][Y]². What are the units of k?
- A. s⁻¹
- B. dm³ mol⁻¹ s⁻¹
- C. dm⁶ mol⁻² s⁻¹
- D. mol dm⁻³ s⁻¹
2. In a two-step mechanism, step 1 is fast and step 2 is slow. Where on the energy profile is the highest barrier?
- A. Step 1
- B. Step 2
- C. Both barriers are equal
- D. There is no barrier for the slow step
3. A plot of ln k against 1/T has gradient −6000 K. What is Ea? (R = 8.31 J K⁻¹ mol⁻¹)
- A. 0.72 kJ mol⁻¹
- B. 6.0 kJ mol⁻¹
- C. 49.9 kJ mol⁻¹
- D. 722 kJ mol⁻¹
4. Which step is bimolecular?
- A. N₂O₄ → 2NO₂
- B. NO₂ + CO → NO + CO₂
- C. 2NO + O₂ → 2NO₂
- D. O₃ → O₂ + O
5. Tripling [A] increases the rate by a factor of 9. What is the order with respect to A?
- A. 0
- B. 1
- C. 2
- D. 3