• 68 questions

AP Chemistry Kinetics Practice Test

Unofficial multiple-choice practice for Unit 5 of AP Chemistry, chemical kinetics: rate laws, mechanisms, energy profiles and catalysis.

What does the rate of a chemical reaction measure?

Pick an answer, then press Check answer. Then you see Correct or Not quite, with the reason. Keys: A to D pick, Enter checks.

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Unofficial practice questions, not affiliated with the College Board. Bank checked October 10, 2026.

Next step Later unit: AP Chemistry equilibriumUnit before: AP Chemistry Unit 4

All 68 questions

Topic 5.1: Reaction rates 6

  • A reaction rate is measured as a change in molar concentration per second. Which unit does it have? Wikipedia, "Reaction rate"; course topic 5.1
  • In the reaction 2 X(g) → Y(g) + Z(g), X is consumed at 0.040 M/s. At what rate does Y form? Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.1
  • In the reaction A + 3 B → 2 C, B is consumed at 0.090 M/s. At what rate does C form? Wikipedia, "Reaction rate"; course topic 5.1
  • Over 40 s the molarity of a reactant drops from 0.50 M to 0.30 M. How fast, on average, is it being used up? Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.1
  • Powdered zinc reacts with acid faster than one lump of zinc of the same mass. Why? AP Chemistry Course and Exam Description, essential knowledge 5.1.A.3; course topic 5.1
  • What does the rate of a chemical reaction measure? Wikipedia, "Reaction rate" and Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.1
Show all 68 questions (62 more)

Topic 5.2: Introduction to rate law 9

  • A reaction has the rate law rate = k[A][B], with the rate in M/s. What are the units of k? Wikipedia, "Reaction rate constant" and AP Chemistry Course and Exam Description, essential knowledge 5.2.A.4; course topic 5.2
  • A reaction has the rate law rate = k[A]²[B]. What is its overall order? Wikipedia, "Rate equation"; course topic 5.2
  • A reaction has the rate law rate = k[X]²[Y]. If [X] is tripled and [Y] is halved, by what factor does the rate change? Wikipedia, "Rate equation"; course topic 5.2
  • Doubling [A] while [B] is held constant makes the initial rate four times as large. What is the order with respect to A? AP Chemistry Course and Exam Description, essential knowledge 5.2.A.5 and Wikipedia, "Rate equation"; course topic 5.2
  • Doubling [B] while [A] is held constant leaves the initial rate unchanged. What is the order with respect to B? Wikipedia, "Rate equation"; course topic 5.2
  • For a given reaction with no catalyst added, which change alters the value of the rate constant k? AP Chemistry Course and Exam Description, essential knowledge 5.2.A.4; course topic 5.2
  • For a reaction with rate = k[A][B]², a run with both concentrations at 0.10 M gives an initial rate of 2.0 × 10⁻³ M/s. What is the value of the rate constant? Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.2
  • Three runs of one reaction: with [A] = 0.10 M and [B] = 0.10 M the initial rate is 2.0 × 10⁻³ M/s; with 0.20 M and 0.10 M it is 4.0 × 10⁻³ M/s; with 0.20 M and 0.20 M it is 1.6 × 10⁻² M/s. What is the rate law? AP Chemistry Course and Exam Description, essential knowledge 5.2.A.5; course topic 5.2
  • Why can the rate law of an overall reaction not be written from its balanced equation alone? Purdue University, General Chemistry Topic Review, "Chemical Kinetics" and Wikipedia, "Molecularity"; course topic 5.2

Topic 5.3: Concentration changes over time 11

  • A first-order reaction has a half-life of 20 min. How long does it take [A] to fall from 0.80 M to 0.10 M? Wikipedia, "Half-life"; course topic 5.3
  • A radioactive sample decays to 1/16 of its starting amount in 32 days. What is its half-life? AP Chemistry Course and Exam Description, essential knowledge 5.3.A.6 and Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3
  • A second-order reaction A → products has k = 0.50 M⁻¹·s⁻¹ and [A]₀ = 0.20 M. What is [A] after 10 s? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3
  • A zeroth-order reaction A → products has k = 0.020 M/s and [A]₀ = 0.80 M. What is [A] after 15 s? Wikipedia, "Rate equation"; course topic 5.3
  • For a first-order reaction, the plot of ln[A] against time has a slope of −0.025 s⁻¹. What is the rate constant? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3
  • For which reaction order is the half-life the same no matter what the starting concentration is? Wikipedia, "Rate equation" and Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3
  • In a first-order reaction, 75% of the reactant is consumed in 40 min. What is the half-life? Wikipedia, "Half-life"; course topic 5.3
  • In the reaction A → products, the concentration of A drops by the same amount every minute until A is gone. What is the order in A? Wikipedia, "Rate equation"; course topic 5.3
  • Kinetics data for A → products are graphed three ways, and only the graph of ln[A] against time is linear. What is the order in A? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3
  • The rate constant of a first-order decomposition is 0.0139 s⁻¹. How long does it take for half of the reactant to be used up? AP Chemistry Course and Exam Description, essential knowledge 5.3.A.5; course topic 5.3
  • Students follow the decomposition of A. Their graph of 1/[A] against time is a straight line, while their graph of ln[A] curves. What is the order in A? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.3

Topic 5.4: Elementary reactions 5

  • An elementary step in which a single molecule breaks apart or rearranges is called Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.4
  • For which kind of reaction can the rate law be written directly from the chemical equation? Wikipedia, "Molecularity"; course topic 5.4
  • In one elementary step, a molecule of A collides with a molecule of B and they react. Which rate law describes that step? Wikipedia, "Molecularity"; course topic 5.4
  • Two molecules of A collide and combine in the single elementary step 2 A → B. How does the rate of this step depend on [A]? Wikipedia, "Molecularity"; course topic 5.4
  • Why are elementary steps in which three particles collide at once rare? AP Chemistry Course and Exam Description, essential knowledge 5.4.A.2 and Wikipedia, "Elementary reaction"; course topic 5.4

Topic 5.5: Collision model 5

  • A modest rise in temperature makes many reactions much faster, although particles collide only slightly more often. What is the main reason? Wikipedia, "Reaction rate" and Purdue University, General Chemistry Topic Review, "Activation Energy"; course topic 5.5
  • In most reactions, what fraction of the collisions between reactant particles leads to products? AP Chemistry Course and Exam Description, essential knowledge 5.5.A.2; course topic 5.5
  • In the collision model, what must be true of a collision for it to lead to reaction? Purdue University, General Chemistry Topic Review, "Activation Energy" and Wikipedia, "Collision theory"; course topic 5.5
  • On a Maxwell–Boltzmann curve of particle energies, a vertical line marks the activation energy. What does the area under the curve to the right of the line show? AP Chemistry Course and Exam Description, essential knowledge 5.5.A.3; course topic 5.5
  • Why does raising the concentration of a reactant usually speed up an elementary reaction? Wikipedia, "Collision theory" and Purdue University, General Chemistry Topic Review, "Chemical Kinetics"; course topic 5.5

Topic 5.6: Reaction energy profile 6

  • On a reaction energy profile, what does the highest point of the curve represent? Wikipedia, "Activation energy" and Wikipedia, "Transition state"; course topic 5.6
  • On an energy profile the products lie 30 kJ/mol below the reactants, and the peak lies 50 kJ/mol above the reactants. What is the overall energy change of the reaction? Wikipedia, "Energy profile (chemistry)"; course topic 5.6
  • On an energy profile the reactants sit at 20 kJ/mol, the peak at 95 kJ/mol and the products at 50 kJ/mol. What is the activation energy of the forward reaction? AP Chemistry Course and Exam Description, essential knowledge 5.6.A.3; course topic 5.6
  • On an energy profile the reactants sit at 40 kJ/mol, the peak at 100 kJ/mol and the products at 10 kJ/mol. What is the activation energy of the reverse reaction? Wikipedia, "Activation energy"; course topic 5.6
  • Two similar reactions run at the same temperature. Reaction 1 has an activation energy of 40 kJ/mol and reaction 2 has 90 kJ/mol. Which is likely to be faster? Wikipedia, "Activation energy"; course topic 5.6
  • What does the Arrhenius equation relate? AP Chemistry Course and Exam Description, essential knowledge 5.6.A.4 and Purdue University, General Chemistry Topic Review, "Activation Energy"; course topic 5.6

Topic 5.7: Introduction to reaction mechanisms 6

  • A mechanism has two steps. Step 1: NO₂ + NO₂ → NO₃ + NO. Step 2: NO₃ + CO → NO₂ + CO₂. What is the overall reaction? Wikipedia, "Reaction mechanism"; course topic 5.7
  • A mechanism has two steps. Step 1: X + O₃ → XO + O₂. Step 2: XO + O → X + O₂. What is the role of X? Wikipedia, "Catalysis" and AP Chemistry Course and Exam Description, essential knowledge 5.11.A.2; course topic 5.7
  • Chemists detect a proposed intermediate in a reacting mixture. What does that finding do for the proposed mechanism? AP Chemistry Course and Exam Description, essential knowledge 5.7.A.4; course topic 5.7
  • In the mechanism NO₂ + NO₂ → NO₃ + NO, then NO₃ + CO → NO₂ + CO₂, which species is a reaction intermediate? Wikipedia, "Reaction intermediate"; course topic 5.7
  • What is a reaction intermediate? Wikipedia, "Reaction intermediate" and Wikipedia, "Reaction mechanism"; course topic 5.7
  • What must be true of the elementary steps of an acceptable reaction mechanism? AP Chemistry Course and Exam Description, essential knowledge 5.7.A.2 and Wikipedia, "Reaction mechanism"; course topic 5.7

Topic 5.8: Reaction mechanism and rate law 5

  • A mechanism has a slow first step, A + B → C, and a fast second step, C + A → D. What rate law does it predict? Wikipedia, "Rate-determining step" and AP Chemistry Course and Exam Description, essential knowledge 5.8.A.1; course topic 5.8
  • A mechanism has a slow first step, NO₂ + NO₂ → NO₃ + NO, and a fast second step, NO₃ + CO → NO₂ + CO₂. What rate law does it predict? AP Chemistry Course and Exam Description, essential knowledge 5.8.A.1 and Wikipedia, "Reaction mechanism"; course topic 5.8
  • A proposed one-step mechanism, 2 A + B → P, predicts rate = k[A]²[B]. Experiments give rate = k[A][B]. What follows? Purdue University, General Chemistry Topic Review, "Chemical Kinetics" and AP Chemistry Course and Exam Description, essential knowledge 5.8.A.1; course topic 5.8
  • The reaction NO₂ + CO → NO + CO₂ has the experimental rate law rate = k[NO₂]². What happens to the rate when [CO] is doubled? Wikipedia, "Reaction mechanism"; course topic 5.8
  • Which step of a multistep mechanism sets the rate of the overall reaction? Wikipedia, "Rate-determining step" and Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics"; course topic 5.8

Topic 5.9: Pre-equilibrium approximation 4

  • A mechanism has a fast, reversible first step, 2 A ⇌ A₂, and a slow second step, A₂ + B → 2 C. What rate law does it predict, written in terms of the reactants? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics" and AP Chemistry Course and Exam Description, essential knowledge 5.9.A.1; course topic 5.9
  • A mechanism has a fast, reversible first step, A + B ⇌ I, and a slow second step, I + B → P. What rate law does it predict? AP Chemistry Course and Exam Description, essential knowledge 5.9.A.1 and Wikipedia, "Rate-determining step"; course topic 5.9
  • For a mechanism with a fast, reversible first step that makes an intermediate, why is the rate law of the slow second step not the final answer? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics" and AP Chemistry Course and Exam Description, essential knowledge 5.9.A.1; course topic 5.9
  • In the pre-equilibrium approximation, what is assumed about the fast first step? Purdue University, General Chemistry Topic Review, "Chemical Reactions and Kinetics" and Wikipedia, "Rate-determining step"; course topic 5.9

Topic 5.10: Multistep reaction energy profile 4

  • A reaction energy profile shows two peaks with a dip between them. How many elementary steps does the mechanism have? Wikipedia, "Energy profile (chemistry)" and AP Chemistry Course and Exam Description, essential knowledge 5.10.A.1; course topic 5.10
  • How many transition states and how many intermediates appear on the energy profile of a three-step mechanism? Wikipedia, "Energy profile (chemistry)" and AP Chemistry Course and Exam Description, essential knowledge 5.10.A.1; course topic 5.10
  • On the energy profile of a two-step reaction, the first peak is the highest point, and the climb to it is much taller than the climb from the dip to the second peak. Which step is rate limiting? Wikipedia, "Energy profile (chemistry)"; course topic 5.10
  • On the energy profile of a two-step reaction, what lies in the dip between the two peaks? Wikipedia, "Energy profile (chemistry)"; course topic 5.10

Topic 5.11: Catalysis 7

  • By what means does a catalyst make a reaction go faster? Wikipedia, "Catalysis" and Wikipedia, "Reaction rate"; course topic 5.11
  • How do many enzymes speed up a reaction? AP Chemistry Course and Exam Description, essential knowledge 5.11.A.3 and Wikipedia, "Enzyme"; course topic 5.11
  • In acid–base catalysis, what happens to a reactant or an intermediate? AP Chemistry Course and Exam Description, essential knowledge 5.11.A.4 and Wikipedia, "Acid catalysis"; course topic 5.11
  • In surface catalysis on a solid metal, what happens to a gaseous reactant at the start of the catalyzed path? AP Chemistry Course and Exam Description, essential knowledge 5.11.A.5 and Wikipedia, "Heterogeneous catalysis"; course topic 5.11
  • On an energy profile, how does a catalyzed path compare with the uncatalyzed path of the same reaction? Wikipedia, "Activation energy"; course topic 5.11
  • What does a catalyst do to the equilibrium constant of a reaction? Purdue University, General Chemistry Topic Review, "Activation Energy"; course topic 5.11
  • When a catalyzed reaction is finished, how much of the catalyst is left? Purdue University, General Chemistry Topic Review, "Activation Energy" and AP Chemistry Course and Exam Description, essential knowledge 5.11.A.2; course topic 5.11

How this list was compiled: Our own questions, written to Unit 5 (Kinetics) of the College Board's AP Chemistry Course and Exam Description, effective fall 2024, https://apcentral.collegeboard.org/media/pdf/ap-chemistry-course-and-exam-description.pdf, read 2026-10-10. Each rule was read on 2026-10-10 in the public page named under its question: the General Chemistry Topic Review of Purdue University, a Wikipedia article or an essential knowledge statement of the course description. Every calculated answer is worked from the numbers the question prints and was worked out a second time on 2026-10-10. Licence: Own work. Short quotations from the public documents named under each question.

How it works

This AP Chemistry kinetics practice test has 68 multiple-choice questions of our own on Unit 5, from reaction rates to catalysis. It is unofficial, and it is not affiliated with or endorsed by the College Board, the owner of AP.

Read the full guide

What Unit 5 covers

The College Board's course description, read October 10, 2026, gives Unit 5 eleven topics and no weights among them, so the spread is ours: reaction rates (6 questions), rate law (9), concentration changes over time (11), elementary reactions (5), collision model (5), energy profile (6), mechanisms (6), mechanism and rate law (5), pre-equilibrium (4), multistep energy profile (4) and catalysis (7).

What is left out, and sources

The description says calculations with the Arrhenius equation are not assessed, so none is here. Rules were read in a Purdue University chemistry review, a Wikipedia article or the description, named under each answer.

  • Orders come from data, never from the coefficients of the overall equation. Only an elementary step shows its own rate law.
  • Match the straight line to the order: [A] against time is zeroth, ln[A] is first, 1/[A] is second.
  • A rate law cannot contain an intermediate. If the slow step has one, replace it using the fast equilibrium before it.

Questions and answers

What unit is kinetics in AP Chemistry?

Unit 5, Kinetics, the fifth of nine units. The course description allows about 13 to 14 class periods for it, and equilibrium follows in Unit 7.

How much of the AP Chem exam is kinetics?

Unit 5 is 7 to 9% of the multiple-choice section, by the College Board's course page. That section has 60 questions in 1 hour 30 minutes and is half of the exam score.

Do you need the Arrhenius equation for the AP Chemistry exam?

Not for calculations: the course description says calculations with it will not be assessed. Know what it relates: the rate constant, the temperature and the activation energy.

How do you find the half-life of a first-order reaction?

Divide 0.693 by the rate constant: t½ = 0.693/k. A first-order half-life does not depend on the starting concentration, which is why radioactive decay has a fixed half-life.

Is this the AP Chemistry Unit 5 Progress Check?

No. The Progress Check is the College Board's own set, given through AP Classroom. The questions on this page are our own, written from the Unit 5 topic list, and none copies or rewords a real exam question.

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