AP Chem · Unit 5 Progress Check

AP Chemistry Unit 5 Progress Check Kinetics walkthrough.

AP Chemistry Unit 5 is kinetics, and the Unit 5 Progress Check MCQ is heavy on rate laws, graph reading, and reaction mechanisms. This walkthrough covers what each question type tests, the traps that cost points, and how to work through them. Explanations only — we never publish AP Classroom answer keys.

Updated August 2026Written by Mahmudul HasanFree · No signup

What Unit 5 covers

Unit 5 is Kinetics. Kinetics is roughly 7–9% of the AP Chemistry exam and pairs closely with equilibrium later in the course.

Reaction rate

How concentration changes over time, and relating rates of different species using coefficients.

Rate laws

rate = k[A]^m[B]ⁿ, with orders determined experimentally — never from coefficients.

Integrated rate laws

Zero, first, and second order, and which plot gives a straight line for each.

Half-life

Constant for first-order reactions; concentration-dependent otherwise.

Reaction mechanisms

Elementary steps, the rate-determining step, intermediates, and catalysts.

Collision theory & activation energy

Why temperature and catalysts change rate, and the Arrhenius relationship.

The Progress Check MCQ: what each question type tests

These are the question patterns that recur on this Progress Check, and what each one is really asking.

Determine the order from data

A table of initial rates. Double one concentration, see what the rate does — that ratio gives the order.

Which plot is linear?

Zero order: [A] vs t. First order: ln[A] vs t. Second order: 1/[A] vs t. Memorise these three.

Mechanism validity

A proposed mechanism must sum to the overall equation and its slow step must match the rate law.

Catalyst vs intermediate

A catalyst appears first as a reactant then is regenerated; an intermediate is produced then consumed.

Energy diagrams

Activation energy is peak minus reactants. Catalysts lower the peak but never change ΔH.

The Progress Check FRQ

Kinetics free response usually gives you experimental data and asks you to determine the rate law, justify it, and connect it to a mechanism. Points come from showing the ratio work that establishes each order, stating that orders are experimental, and explicitly linking the rate-determining step to the observed rate law.

Where students lose the most points

Reading orders off the balanced equation

Orders come from experiment only. This is the single most common kinetics error.

Confusing rate constant with rate

k depends on temperature, not concentration. Rate depends on both.

Assuming every half-life is constant

Only first-order half-lives are concentration-independent.

Mixing up intermediates and catalysts

Check the order of appearance across the steps.

Thinking a catalyst changes ΔH

It lowers activation energy and speeds both directions; the enthalpy change is untouched.

How to work through this unit

For any rate-law data table, compare two trials where only one concentration changes. If doubling it doubles the rate, order 1; quadruples, order 2; no change, order 0.

Once you have finished the Progress Check, put your raw score into our AP Chemistry Calculator to see roughly where that pace puts you on the 1–5 scale, and use the AP Chemistry Review for the full exam format and study plan.

Frequently asked questions

Quick answers — written by humans, not a chatbot.

What does the AP Chemistry Unit 5 Progress Check cover?

Kinetics: reaction rates, experimentally determined rate laws, integrated rate laws and their linear plots, half-life, reaction mechanisms, and activation energy.

How do you find reaction order from a data table?

Compare two trials in which only one reactant concentration changes, then see how the rate responds — doubling that gives first order, quadrupling gives second order, no change gives zero order.

Which plot is linear for a first-order reaction?

ln[A] versus time. Zero order is [A] versus time, and second order is 1/[A] versus time.

Do you post AP Chemistry Unit 5 answers?

No. We publish walkthroughs of the reasoning and the common traps rather than AP Classroom answer keys.