7–9% of the AP exam. 8 key topics. 4 common errors analyzed.
Unit 6 (Thermochemistry) 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.
Using only the mass of the solute (e.g., the solid being dissolved) rather than the total solution mass when applying q = mcΔT in a calorimetry problem, systematically underestimating heat absorbed
Applying Hess's Law with incorrect sign conventions — forgetting to negate ΔH when reversing a reaction, or forgetting to multiply ΔH by the stoichiometric coefficient when scaling a reaction
Conflating bond enthalpy calculations (energy to break bonds in reactants minus energy released forming bonds in products) with standard enthalpies of formation, mixing the two methods in a single calculation
Failing to convert temperatures from Celsius to Kelvin in calorimetry or gas-law sub-parts embedded within thermochemistry problems
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.