18–22% of the AP exam. 8 key topics. 4 common errors analyzed.
Unit 3 (Properties of Substances and Mixtures) is part of the AP Chemistry core curriculum. Work through each key topic in sequence, constructing ICE tables, net ionic equations, or energy diagrams as appropriate.
These are the most frequently penalized mistakes on AP exam FRQs and MCQs. Review each before your next practice session.
Identifying hydrogen bonding as an intramolecular covalent bond rather than an intermolecular force between molecules, or incorrectly attributing it to atoms that cannot form hydrogen bonds (e.g., C–H···O)
Justifying boiling point differences by citing molar mass alone without explaining London dispersion force magnitude or the role of molecular surface area and polarizability
Applying Beer-Lambert Law without accounting for path length units or failing to distinguish between absorbance and transmittance
Using ideal gas law relationships (e.g., PV = nRT) when the problem context signals real-gas deviations (high pressure, low temperature), without qualitatively applying van der Waals corrections
Our worked solutions and practice questions are original instructional content created by Tian2 AP. They are aligned to the concepts and skills described in College Board’s Course and Exam Description and are not reproductions of, or affiliated with, College Board’s official materials.