Lesson 3.1.9.1

3.1.9.1 Rate equations Quiz: AQA Chemistry, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.9.1, Rate equations: 20 multiple choice questions for the AQA Chemistry (7405), Unit 1: Physical chemistry, written with Revision Ninja.

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The 20 questions

  1. In a rate equation Rate = k[A]^m[B]^n, what is the order of reaction with respect to A?

    • The concentration of A at the start of the reaction, which determines the power to which it is raised in the rate
    • The total number of moles of A that react in one step, which is always the power of its concentration in the rate
    • The coefficient of A in the balanced chemical equation, which always gives the power to which the concentration is raised
    • The power m to which the concentration of A is raised in the rate equation

  2. What is the rate constant, k, in a rate equation?

    • The rate of reaction at a fixed concentration of reactants, which never changes
    • The activation energy divided by the temperature in kelvin
    • The total number of collisions per second in the reaction mixture
    • The proportionality constant linking the rate to the concentrations, which varies with temperature

  3. Which values can the orders m and n take in the rate equations you are expected to use at A level?

    • Only 1 and 2, never zero
    • 0, 1 and 2 only
    • Any integer, including 3 and 4
    • Any value including fractions such as 1/2

  4. A reaction has the rate equation Rate = k[A][B]. What are the units of k when concentrations are in mol dm^-3 and rate in mol dm^-3 s^-1?

    • s^-1
    • dm^3 mol^-1 s^-1
    • mol dm^-3 s^-1
    • mol^-1 dm^3

  5. A first-order reaction has Rate = k[A]. What are the units of k?

    • s^-1
    • dm^3 mol^-1 s^-1
    • dm^6 mol^-2 s^-1
    • mol dm^-3 s^-1

  6. A zero-order reaction has Rate = k. What are the units of k when rate is in mol dm^-3 s^-1?

    • dm^3 mol^-1 s^-1
    • mol dm^-3 s^-1
    • mol^-1 dm^3 s
    • s^-1

  7. For a reaction with Rate = k[A]^2 and k = 0.50 dm^3 mol^-1 s^-1, what is the rate when [A] = 0.20 mol dm^-3?

    • 0.0080 mol dm^-3 s^-1
    • 0.40 mol dm^-3 s^-1
    • 0.020 mol dm^-3 s^-1
    • 0.10 mol dm^-3 s^-1

  8. For Rate = k[A][B]^2 with k = 2.0 dm^6 mol^-2 s^-1, [A] = 0.10 and [B] = 0.20 mol dm^-3, what is the rate?

    • 0.10 mol dm^-3 s^-1
    • 0.040 mol dm^-3 s^-1
    • 0.0080 mol dm^-3 s^-1
    • 0.0040 mol dm^-3 s^-1

  9. How does an increase in temperature affect the rate constant k?

    • It decreases k only for reactions with a positive activation energy
    • It increases k, because more molecules have energy above the activation energy
    • It decreases k, because molecules move too fast to collide effectively
    • It has no effect on k, because only concentration appears in the rate equation

  10. Which rearrangement of k = Ae^(-Ea/RT) allows a straight-line graph of experimental data to be plotted?

    • ln k = -Ea/(RT) + ln A
    • k = -Ea/(RT) + A
    • ln k = Ea/(RT) - ln A
    • 1/k = Ea/(RT) + A

  11. The rate constant k is measured at several temperatures. What is the gradient of a graph of ln k against 1/T?

    • Ea/R
    • ln A
    • -Ea/R
    • -R/Ea

  12. For a reaction with k = A e^(-Ea/RT), A = 1.0 x 10^10 s^-1, Ea = 60 kJ/mol and T = 300 K, what is k? Use R = 8.314 J K^-1 mol^-1.

    • About 36 s^-1
    • About 0.036 s^-1
    • About 0.36 s^-1
    • About 3.6 s^-1

  13. For a zero-order reaction, what is the gradient of a graph of concentration against time?

    • -k, because the concentration falls at a constant rate
    • -k^2, because the rate is proportional to the square of the rate constant
    • -1/k, because the concentration falls exponentially
    • +k, because the concentration rises at a constant rate

  14. A student doubles [B] and finds that the rate is unchanged. What does this show about the order with respect to B?

    • The reaction is second order with respect to B
    • The reaction is first order with respect to B only at high temperature
    • The reaction is zero order with respect to B
    • The reaction is first order with respect to B

  15. The rate equation is Rate = k[A][B]^2. By what factor does the rate increase when [A] is tripled and [B] is doubled?

    • 24
    • 9
    • 12
    • 6

  16. Initial rate data: [A] = 0.10, [B] = 0.10 mol dm^-3 gives rate 2.0 x 10^-3 mol dm^-3 s^-1; [A] = 0.20, [B] = 0.10 gives rate 8.0 x 10^-3. With Rate = k[A]^2, what is k?

    • 0.20 dm^3 mol^-1 s^-1
    • 2.0 dm^3 mol^-1 s^-1
    • 0.020 dm^3 mol^-1 s^-1
    • 0.50 dm^3 mol^-1 s^-1

  17. The rate equation for a reaction is Rate = k[A]^2. What does this suggest about the rate-determining step?

    • Two molecules of A are involved in the rate-determining step
    • Three molecules of A are involved in the rate-determining step
    • The rate-determining step is the final fast step of the reaction
    • One molecule of A is involved in the rate-determining step and B is not involved

  18. Why is it a mistake to deduce the order of a reaction from its balanced equation?

    • Orders are always zero for any reaction that involves a catalyst
    • Orders must be found from experimental data, and they can differ from the stoichiometric coefficients
    • Orders always equal the stoichiometric coefficients, so the balanced equation is sufficient
    • Orders can only be found from the activation energy, not from concentration data

  19. A reaction is first order in A, with Rate = k[A]. If [A] is doubled at constant temperature, what happens to the rate?

    • It is unchanged
    • It doubles
    • It halves
    • It quadruples

  20. For Rate = k[A]^2, if [A] is halved at constant temperature, by what factor does the rate change?

    • It falls to one quarter of its original value
    • It falls to one half of its original value
    • It is unchanged from its original value
    • It doubles from its original value

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