Most students who sit it get a 3 or higher: 77.9% in May 2025. A 5 is harder, at 17.9%. The difficulty is less the facts than doing the calculations accurately and explaining them at the level of particles.
Students in May 2025
168,833
Scored 3 or higher
77.9%
Scored 5
17.9%
Mean score
3.36
What makes it hard
Calculations: stoichiometry, gas laws, equilibrium, pH, thermochemistry and cell potentials, each with units and the right number of significant figures.
Particle-level reasoning: many questions ask why, in terms of forces between particles, structure or collisions, not just what happens.
Free response: half the score, with long questions that chain several calculations and justifications together.
Unit 3, Properties of Substances and Mixtures, is 18–22% of Section I on its own.
What makes it easier
The equations and constants sheet and the periodic table are given on the exam, so you practice using them rather than memorizing them.
The course is nine units with published weights, so you can plan your time.
Calculation types repeat: drilling a few kinds of problem until they are automatic frees time for the harder questions.
Try 2 questions
Question 1
Initial rate data. Experiment 1: [NO] 0.0100 M, [H₂] 0.0100 M, rate 2.5 × 10⁻⁴ M/s. Experiment 2: [NO] 0.0200 M, [H₂] 0.0100 M, rate 1.0 × 10⁻³ M/s. Experiment 3: [NO] 0.0100 M, [H₂] 0.0200 M, rate 5.0 × 10⁻⁴ M/s.
Experiment
[NO] (M)
[H₂] (M)
Initial rate (M/s)
1
0.0100
0.0100
2.5 × 10⁻⁴
2
0.0200
0.0100
1.0 × 10⁻³
3
0.0100
0.0200
5.0 × 10⁻⁴
The initial rate of 2NO(g) + 2H₂(g) → N₂(g) + 2H₂O(g) was measured in three experiments at the same temperature. Which rate law is consistent with the data?
Question 2
What is the molecular geometry of phosphorus trichloride, PCl₃?
In May 2025, 77.9% of the 168,833 students who took AP Chemistry scored 3 or higher. Many US colleges grant credit or placement for 3 and above, but each college sets its own policy.
What share of AP Chemistry students earn a 5?
17.9% in May 2025 (30,143 students).
What is the hardest part of AP Chemistry?
For most students it is the calculations under time pressure, and explaining results in terms of particles. Regular practice with both, using the equations sheet, helps most.