Lesson 3.2.2

3.2.2 Reaction rates Quiz: OCR Chemistry, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.2.2, Reaction rates: 20 multiple choice questions for the OCR Chemistry (H432), Unit 2: Periodic table and energy, written with Revision Ninja.

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The 20 questions

  1. What increases when reactant concentration is increased, causing a higher reaction rate?

    • Collision frequency
    • Enthalpy change
    • Average kinetic energy
    • Activation energy

  2. What quantity is determined from the gradient of a tangent to a concentration-time graph?

    • Enthalpy change
    • Activation energy
    • Reaction rate
    • Equilibrium constant

  3. How does a catalyst increase the rate of a chemical reaction?

    • Increases activation energy
    • Increases temperature
    • Increases collision frequency
    • Lowers activation energy

  4. What describes a homogeneous catalyst relative to the reactants in a reaction?

    • Same physical state
    • Solid state only
    • Aqueous state only
    • Different physical state

  5. A solid platinum catalyst speeds up a reaction between gases. What type of catalyst is it?

    • Heterogeneous
    • Autocatalyst
    • Inhibitor
    • Homogeneous

  6. Why do catalysts lower energy demand and costs in industrial chemical processes?

    • Lower operating temperatures
    • Increased activation energy
    • Higher product yield
    • Higher operating pressures

  7. What property of gas molecules is plotted on the horizontal axis of a Boltzmann distribution graph?

    • Molecular kinetic energy
    • Activation energy
    • Molecular mass
    • Reaction rate

  8. Why does a small temperature increase cause a large increase in reaction rate?

    • More exceed activation energy
    • Activation energy decreases
    • Collision frequency doubles
    • Molecular mass increases

  9. On a Boltzmann distribution curve, how does adding a catalyst change the activation energy line?

    • Shifts upward
    • Shifts right
    • Shifts left
    • Remains unchanged

  10. A concentration-time graph has a tangent that falls by 0.40 mol dm-3 over 10 s. What is the rate?

    • 0.040 mol dm-3 s-1
    • 0.004 mol dm-3 s-1
    • 4.0 mol dm-3 s-1
    • 0.40 mol dm-3 s-1

  11. 60 cm3 of gas is collected in the first 30 s of a reaction using a gas syringe. What is the average rate?

    • 30 cm3 s-1
    • 0.5 cm3 s-1
    • 60 cm3 s-1
    • 2.0 cm3 s-1

  12. A reaction loses 1.20 g of mass in 60 s. What is the average rate in g s-1?

    • 0.0200 g s-1
    • 0.00200 g s-1
    • 1.20 g s-1
    • 0.720 g s-1

  13. Why does powdered calcium carbonate react faster with hydrochloric acid than large marble chips?

    • Higher concentration
    • Larger surface area
    • Higher particle energy
    • Lower activation energy

  14. Why does increasing the pressure of a gaseous reaction increase its reaction rate?

    • Lower activation energy
    • Higher particle energy
    • Higher collision frequency
    • Increased enthalpy change

  15. Why does the rate of reaction decrease over time as reactants are consumed?

    • Rising reaction temperature
    • Increasing product concentration
    • Falling collision frequency
    • Increasing activation energy

  16. A solution has a reaction rate of 0.0050 mol dm-3 s-1 in a 0.25 dm3 vessel. How many moles of reactant are used per second?

    • 0.0050 mol s-1
    • 0.00125 mol s-1
    • 0.0125 mol s-1
    • 0.0200 mol s-1

  17. What happens to the peak of a Boltzmann distribution curve when temperature increases?

    • Shifts upper left
    • Remains unchanged
    • Shifts upper right
    • Shifts lower right

  18. Which physical quantity is directly measured using a gas syringe to monitor reaction rate?

    • Gas volume
    • Gas pressure
    • Gas mass
    • Gas temperature

  19. How does adding a catalyst affect the peak on an enthalpy profile diagram?

    • Lower peak
    • Shifted right
    • No change
    • Higher peak

  20. What main physical advantage do heterogeneous catalysts have over homogeneous catalysts in industry?

    • Lower surface area
    • Higher activation energy
    • Greater toxicity
    • Easy separation

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