AP Chemistry free-response questions: how to score well
The free-response section is half of your AP Chemistry score: 7 questions in 1 hour 45 minutes. Here is how it is built, how points are awarded and how to write answers that earn them.
On this page
The format
| Section | Questions | Time | Score |
|---|---|---|---|
| I: Multiple choice | 60 | 1 hour 30 minutes | 50% |
| II: Free response | 7: 3 long (10 points each) and 4 short (4 points each) | 1 hour 45 minutes | 50% |
The 3 long questions are worth 10 points each and the 4 short ones 4 points each, 46 points in total. A calculator is allowed, and you have the periodic table and the equations and constants sheet.
Timing
About 23 minutes for each long question and 9 minutes for each short question leaves a few minutes to check. Short questions are quick points: do not leave them until the end and run out of time.
How points are awarded
- Calculations: show the setup with units. A point is often given for the setup and another for the answer, and a wrong earlier answer used correctly later can still earn credit.
- Explanations: name the relevant particles and the forces or interactions between them. “Stronger intermolecular forces” is not enough; say which forces, between which particles, and why they are stronger.
- Justify with data: when a question gives a table or graph, refer to specific values from it.
A short worked question
A 0.150 M solution of a weak acid HA has pH 2.85. (a) Calculate [H3O+]. (b) Calculate Ka. (c) Calculate the percent ionisation.
- [H3O+] = 10−2.85 = 1.41 × 10−3 M.
- Ka = x2/(0.150 − x) = (1.41 × 10−3)2/0.1486 = 1.34 × 10−5.
- Percent ionisation = 1.41 × 10−3/0.150 × 100 = 0.94%.
Each part shows the expression before the number, which is what earns the setup point.
Practise with the real questions
Every released AP Chemistry free-response question, with scoring guidelines and sample responses, is on our AP Chemistry past papers page, along with a topic index of what each question tests.
Common mistakes
- Giving a final number without the setup.
- Explaining with a rule (“like dissolves like”) instead of particles and forces.
- Spending too long on one long question and rushing the short ones.
Frequently asked questions
How many free-response questions are on AP Chemistry?
Seven: 3 long questions worth 10 points each and 4 short questions worth 4 points each, in 1 hour 45 minutes.
Can I use a calculator on the AP Chemistry free-response section?
Yes. A calculator is allowed throughout the exam.
Where can I find past AP Chemistry free-response questions?
On AP Central, and collected with scoring guidelines on our AP Chemistry past papers page.
Key takeaways
- 7 questions: 3 long (10 points) and 4 short (4 points), 105 minutes.
- Show the setup, then the number, with units.
- Explain with particles and forces, and quote data when it is given.
Source: College Board, AP Central course and exam pages for AP Chemistry, checked 20 October 2026.