16.1.2 Measuring rates and half-lives Quiz: Pearson Edexcel Chemistry, Unit 16

The 20 questions

1. What is the time taken for a reactant's concentration to fall by half called?

   • Half-life
   • Induction period
   • Retention time
   • Rate constant

2. How does the half-life of a first-order reaction change as concentration decreases?

   • Increases linearly
   • Halves
   • Remains constant
   • Doubles

3. What graphical feature on a concentration-time curve indicates a second-order reaction?

   • Zero half-life
   • Constant half-life
   • Increasing half-life
   • Decreasing half-life

4. In the initial-rate method, what is varied between separate experimental runs?

   • One initial concentration
   • Total reaction time
   • Temperature only
   • Catalyst mass

5. In a clock reaction, what parameter is measured to estimate the initial rate?

   • Mass lost
   • Time taken
   • Temperature rise
   • Volume change

6. What is the standard unit for the rate of a chemical reaction?

   • mol dm-3
   • mol dm-3 s-1
   • dm3 s-1
   • mol s-1

7. Why are reaction samples quenched before titrating in rate experiments?

   • Increase the yield
   • Dissolve the precipitate
   • Neutralise the acid
   • Stop the reaction

8. A first-order reaction has a rate constant k = 0.0462 s-1. What is its half-life?

   • 30.0 s
   • 7.50 s
   • 15.0 s
   • 21.6 s

9. A first-order reaction has a half-life of 40 s. How long does it take for the concentration to fall from 0.80 to 0.10 mol dm-3?

   • 60 s
   • 120 s
   • 80 s
   • 160 s

10. What is the shape of a concentration-time graph for a zero-order reaction?

    • Downward straight line
    • Horizontal straight line
    • Downward curve
    • Upward curve

11. How is the instantaneous reaction rate found from a concentration-time curve?

    • Midpoint of curve
    • Gradient of tangent
    • Area under curve
    • Intercept on y-axis

12. A first-order reaction has [A]0 = 0.200 mol dm-3 and k = 0.0100 s-1. What is [A] after 100 s?

    • 0.121 mol dm-3
    • 0.0736 mol dm-3
    • 0.100 mol dm-3
    • 0.0368 mol dm-3

13. A first-order reaction takes 60 s for the concentration to fall from 1.00 to 0.25 mol dm-3. What is its half-life?

    • 15 s
    • 20 s
    • 60 s
    • 30 s

14. A first-order reaction has a half-life of 25 s. What is its rate constant?

    • 0.693 s-1
    • 2.77 s-1
    • 0.0400 s-1
    • 0.0277 s-1

15. A student plots concentration against time and obtains a straight line with a gradient of -0.030 mol dm-3 s-1. What is the rate of reaction?

    • 0.030 mol dm-3 s-1
    • 33 mol dm-3 s-1
    • 0.30 mol dm-3 s-1
    • 0.0030 mol dm-3 s-1

16. What does a horizontal plateau on a gas volume against time graph represent?

    • Zero-order reaction
    • Maximum rate
    • Reaction complete
    • Half-life reached

17. A first-order reaction takes 50 s to halve the concentration. How long does it take to fall from 100% to 12.5% of its initial value?

    • 200 s
    • 150 s
    • 125 s
    • 100 s

18. Why is a clock reaction's measured rate only an approximation of initial rate?

    • Measures overall rate
    • Measures equilibrium rate
    • Measures average rate
    • Measures final rate

19. If consecutive half-lives double as concentration halves, what is the reaction order?

    • Zero order
    • First order
    • Third order
    • Second order

20. In a gas-evolving experiment the volume increases by 24 cm3 in 40 s. What is the average rate?

    • 960 cm3 s-1
    • 0.60 cm3 s-1
    • 1.67 cm3 s-1
    • 0.33 cm3 s-1

Related quizzes

• Rate equations and orders of reaction Quiz · 16.1.1 · 20 questions
• Determining orders from experimental data Quiz · 16.1.3 · 20 questions
• Reaction mechanisms and the rate-determining step Quiz · 16.1.4 · 20 questions
• Activation energy from rate data Quiz · 16.1.5 · 20 questions
• Sub-atomic particles, isotopes and relative masses Quiz · 1.1.1 · 20 questions
• Dynamic equilibrium and the equilibrium constant Kc Quiz · 10.1.1 · 20 questions
• Kp and partial pressures Quiz · 11.1.1 · 20 questions
• Brønsted-Lowry acids, bases and conjugate pairs Quiz · 12.1.1 · 20 questions
• Lattice energy and Born-Haber cycles Quiz · 13A.1 · 20 questions
• Standard electrode potentials and the hydrogen electrode Quiz · 14.1.1 · 20 questions