The AP Chemistry equation sheet, explained
In the AP Chemistry exam you get a periodic table and a sheet of equations and constants. Knowing what is on it, and what each equation is for, saves time and stops you hunting for formulas under pressure.
On this page
What you get in the exam
College Board provides reference materials for the whole exam: a periodic table and a list of equations and constants. They are available in Bluebook on exam day and printed for the free-response section. Check the current version on AP Central before your exam, and practise with it from the start of the year.
The main equations, grouped by topic
| Topic | Equations | Used for |
|---|---|---|
| Atomic structure | E = hν, c = λν | photon energy, frequency and wavelength |
| Gases | PV = nRT, Ptotal = PA + PB + …, PA = Ptotal × XA | ideal gas calculations and partial pressures |
| Solutions and spectroscopy | M = moles of solute / litres of solution, A = εbc | molarity and Beer's law |
| Kinetics | ln[A]t − ln[A]0 = −kt, 1/[A]t − 1/[A]0 = kt, t½ = 0.693/k | integrated rate laws and half-life |
| Equilibrium, acids and bases | pH = −log[H+], pH = pKa + log([A−]/[HA]), Kw = 1.0 × 10−14 at 25°C | pH, buffers and the water constant |
| Thermochemistry | q = mcΔT, ΔG° = ΔH° − TΔS° | calorimetry and spontaneity |
| Electrochemistry | ΔG° = −nFE°, I = q/t | cell potential and electrolysis |
The sheet also gives constants such as the gas constant R (8.314 J mol−1 K−1, or 0.08206 L atm mol−1 K−1), Faraday's constant (96 485 C per mole of electrons), Planck's constant, the speed of light and Avogadro's number.
Worked examples
Calorimetry. 50.0 g of water warms by 6.0°C. With c = 4.18 J g−1 °C−1, q = mcΔT = 50.0 × 4.18 × 6.0 = 1254 J, about 1.25 kJ absorbed by the water.
Weak acid. A 0.150 M solution of a weak acid has pH 2.85. [H+] = 10−2.85 = 1.41 × 10−3 M, so Ka = (1.41 × 10−3)2 / (0.150 − 0.00141) = 1.34 × 10−5.
Using the sheet well
- Pick the right R. Use 0.08206 with litres and atmospheres, and 8.314 with joules.
- Write the equation first, then substitute. On free-response questions the setup earns points even if the arithmetic slips.
- Know the units of every symbol, especially for k in rate laws, which depend on the order of the reaction.
Common mistakes
- Using 8.314 for R with litres and atmospheres.
- Using degrees Celsius instead of kelvin in PV = nRT or ΔG° = ΔH° − TΔS°.
- Mixing kJ and J when combining ΔH° and TΔS°.
Frequently asked questions
Do you get an equation sheet in AP Chemistry?
Yes. You get a periodic table and a sheet of equations and constants for the whole exam.
Is the periodic table provided in AP Chemistry?
Yes, as part of the reference materials.
Which value of R should I use?
0.08206 L atm mol−1 K−1 for gas calculations in litres and atmospheres, and 8.314 J mol−1 K−1 for energy calculations such as ΔG° = −RT ln K.
Key takeaways
- You get a periodic table and a sheet of equations and constants.
- Know which equation fits each topic before the exam.
- Watch units: kelvin, joules versus kilojoules, and the right R.
Source: College Board, AP Central course and exam pages for AP Chemistry, checked 20 October 2026.