Everything you need in one place — an interactive ebook for all 9 units, 30+ simulators, and exam-style practice. Explore free for 15 days, then $15/year for full access.
College Board's official unit weighting lists Unit 3 (Properties of Substances & Mixtures) as the single largest chunk of the exam — but tagging real past MCQs shows Bonding (15.1%) is actually the most-tested single topic, and Acids and Bases and Equilibrium tie at 13.2% each. On the free-response side, Thermodynamics (25%) and Equilibrium (22.2%) alone account for nearly half of all FRQ points — the highest-yield topics to master for writing full-credit answers.
Section I · 2012, 2014-2019 official/practice exams · n = 325 questions
Section II · free-response questions, same exams · n = 36 questions
2013's official exam is excluded — our extraction of that particular PDF is still incomplete and will be added once resolved.
Interactive Labs
30+ interactive simulators mapped to AP Chemistry Units 1–9. Titration, equilibrium, kinetics, electrochemistry, VSEPR, quantum orbitals, and more.
Browse All Simulations →Interactive Study Guide
Full AP Chemistry interactive ebook — all 9 units with concept explanations, KaTeX formulas, practice MCQs, flashcard decks, and simulation embeds.
Open Ebook →MCQ & FRQ Practice
Timed MCQ practice sets and FRQ past papers aligned to the AP Chemistry exam format. Build exam stamina and identify weak units before test day.
Start Practice →Atomic Structure & Properties
7–9% of exam
Compound Structure & Properties
7–9% of exam
Properties of Substances & Mixtures
18–22% of exam
Chemical Reactions
7–9% of exam
Kinetics
7–9% of exam
Thermochemistry
7–9% of exam
Equilibrium
7–9% of exam
Acids & Bases
11–15% of exam
Thermodynamics & Electrochemistry
7–9% of exam
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