AP Chemistry Free Response QuestionsFRQ Archive & Practice (2019 to 2026)

What do AP Chemistry FRQs test?

Chemical reasoning applied to novel experiments and unfamiliar systems, not formula recall alone.

Section II is half of the AP Chemistry score and it is where most exam outcomes are decided. The multiple choice section tests breadth; the free response questions test whether you can read an experimental setup, interpret particulate level diagrams, set up a quantitative calculation with correct units, and justify a claim with a named chemical principle. According to the AP Chemistry Course and Exam Description published by College Board, the six Science Practices assessed on the exam (Models and Representations, Question and Method, Representing Data and Phenomena, Model Analysis, Mathematical Routines, and Argumentation) are all visible in the FRQ section. A student who memorizes equations but cannot explain why a buffer resists pH change, or who can write the Gibbs equation but cannot assign the correct sign to delta G, will still underperform on Section II even with a strong multiple choice result.

Long versus short AP Chemistry FRQs

Three 10 point long questions test multi concept reasoning; four 4 point short questions each focus on a single concept or calculation.

Section II always has 7 questions: 3 long questions (Q1 to Q3, 10 points each, 30 points total) and 4 short questions (Q4 to Q7, 4 points each, 16 points total). The 105 minute time limit means you have roughly 25 minutes per long question and 11 minutes per short question as a planning guide. A calculator is permitted throughout Section II, and College Board provides a periodic table and an equations and constants sheet.

How are AP Chemistry FRQs scored?

Analytic point rubrics, scored by trained Readers, with partial credit awarded part by part.

Each free response question has an official College Board scoring guideline that lists the exact requirement for every available point. Readers award a point only when a response satisfies that requirement: the correct calculation setup with units carried through, the correct mechanism stated explicitly, or the correct justification connecting the evidence to the claim. Partial credit accumulates across all parts, so there is no penalty for an incorrect attempt and you should always write something for every subpart. The rubric does not award points for restating a conclusion without the underlying reasoning, which is why the national mean on low scoring questions falls well below their maximum. Per College Board's 2023 Chief Reader Report: 'We saw many correct answers that we could not give credit for because they lacked work.' Showing the dimensional analysis, not just the final number, is required. The full year by year scoring guidelines, and how the FRQ raw score converts to the composite, are covered on the AP Chemistry scoring guidelines page.

Worked example: how a real AP Chemistry FRQ was scored

2024 Long Q1, lactic acid titration and calorimetry. Maximum score 10, national mean 4.43.

This is the released 2024 Long Question 1: a multi concept question covering weak acid structure, a weak acid strong base titration curve, particulate diagram interpretation, and calorimetry. With a national mean of 4.43 out of 10, it is among the lower scoring long questions in the recent window. The scoring guideline and Chief Reader Report document exactly why. Each part below pairs the official rubric requirement with a response that earns the point and one that does not.

1. Part (c): Approximate the pKa of lactic acid from the titration curve

   Rubric: Point earned for reading the pH at the half equivalence point from the graph and recognizing that pH equals pKa at that point. The correct approximation is approximately 3.9 (acceptable range 3.7 to 4.0).

   Earns the point: The pH at the half equivalence point on the curve reads approximately 3.9, and because pH equals pKa at the half equivalence point, the pKa of lactic acid is approximately 3.9.

   Loses the point: The pKa is approximately 8, read from the pH at the equivalence point of the titration curve. (Reads the equivalence point pH instead of the half equivalence point pH, which is the most common error documented in the Chief Reader Report for this part.)

2. Part (d)(i) and (d)(ii): Place an X on the titration curve to match a particle diagram showing more lactic acid than lactate ion, then justify the placement

   Rubric: Point earned for placing the X before the half equivalence point (between approximately 3 mL and the half equivalence point) and justifying it by stating that the particle diagram shows more lactic acid particles than conjugate base particles, which corresponds to a region where pH is less than pKa.

   Earns the point: The diagram shows more lactic acid particles than lactate ions, so the solution is before the half equivalence point where [HA] is greater than [A-] and pH is below pKa. The X is placed at approximately 4 to 5 mL on the curve.

   Loses the point: The diagram shows half the number of lactate ions compared to lactic acid particles, so the titration is at the half equivalence point. (Misidentifies the ratio in the particle diagram and places the X at the half equivalence point rather than before it; the Chief Reader Report flags this as the most common error on parts (d)(i) and (d)(ii).)

3. Part (e)(ii): Calculate the molar enthalpy of reaction in kJ per mol from the calorimetry data

   Rubric: Point earned for using the heat absorbed by the solution from part (e)(i), switching the sign to convert from q solution to q reaction, converting joules to kilojoules, and dividing by the correct moles of reaction. The correct sign for an exothermic reaction is negative.

   Earns the point: q reaction equals negative q solution, which gives negative 2.7 kJ. Moles of reaction equals 0.100 L times 0.500 mol/L equals 0.0500 mol. Molar enthalpy of reaction equals negative 2.7 kJ divided by 0.0500 mol equals negative 54 kJ per mol.

   Loses the point: The molar enthalpy is positive 54 kJ per mol, calculated by adding the moles of lactic acid and the moles of NaOH (0.050 plus 0.050 equals 0.10 mol) as the denominator. (Two documented errors combined: wrong sign for an exothermic process, and using the sum of both reactants' moles rather than the moles of either single equimolar reactant as the denominator. The Chief Reader Report identifies these as the least accessible subparts of Q1.)

Across all three part groups the pattern is the same: students knew the relevant chemistry well enough to attempt an answer, but lost points because the rubric requires a specific step that was skipped or stated incorrectly. Reading the equivalence point instead of the half equivalence point on the titration curve, misidentifying a ratio in a particle diagram, and dropping the sign on an enthalpy calculation are not content gaps; they are precision gaps. Per the 2024 Chief Reader Report: 'Students perform better on experiment based questions when they have experienced the lab in class.' Practicing against the official scoring guideline, and grading your own responses line by line, is the most direct way to close those gaps before the exam.

Common AP Chemistry FRQ mistakes

1. 01

   Writing the dimensional analysis chain as three explicit lines, not just the final number

   Per the 2023 Chief Reader Report (Q1), many students who knew the correct answer lost the calculation point because they wrote only the result. The rubric awards the point for a complete setup, not for the answer. On every quantitative subpart, write three lines: (1) the equation with the quantity you are solving for isolated, (2) the substitution with the given values including their units, and (3) the unit algebra carried through to the answer. A response following this sequence earns the calculation point even when the arithmetic contains a minor error. A bare answer, even a correct one, earns nothing. Per the 2024 Chief Reader Report (Q1 Part e, Q3 Part d), this three line discipline also prevents the sign drop errors that cost additional points on thermodynamic calculations.

   AP Chemistry Chief Reader Reports 2023 (Q1), 2024 (Q1 Part e, Q3 Part d), 2025 (multiple quantitative subparts)

2. 02

   Using the equivalence point pH as the pKa on a weak acid titration curve

   On acid base titration questions, the most common error on the pKa subpart is reading the equivalence point pH from the titration curve and reporting it as the pKa of the weak acid. The rubric requires identifying the half equivalence point, where exactly half the acid has been neutralized and pH equals pKa. Per the 2024 Chief Reader Report (Q1, Part c), this error produced the incorrect answer pKa approximately equals 8 (the equivalence point pH) instead of the correct approximation of 3.9. Locate the half equivalence point first, which is at half the equivalence volume, then read the pH at that point.

   AP Chemistry Chief Reader Report 2024 (Q1, Part c)

3. 03

   Reading the prompt verb before answering an explanation or justification subpart

   AP Chemistry FRQ prompts use three distinct instruction verbs that each require a different response depth: 'identify' asks only for the name of a property, trend, or species; 'explain' requires the mechanism connecting the observation to a chemical principle; 'justify' requires evidence and a logical argument showing why a claim must be true. Per the 2023 Chief Reader Report (Q6, intermolecular forces), students lost points on a justification subpart by giving the correct direction of the trend without naming the molecular mechanism, which the rubric requires. Per the 2025 Chief Reader Report (Q1, Coulomb's law), students identified the correct relationship but applied it to the wrong quantity: they used the radius of a single atom rather than the internuclear distance between the two interacting charges. Before writing, read the prompt verb, decide which depth it calls for, and write that depth explicitly.

   AP Chemistry Chief Reader Reports 2023 (Q6, intermolecular forces justification) and 2025 (Q1, Coulomb's law application)

4. 04

   Determining the sign of a thermodynamic or electrochemical answer from physical reasoning before doing the arithmetic

   On calorimetry, Gibbs free energy, and cell potential subparts, the most reliable way to assign the correct sign is to decide it from the physical situation before the calculation begins, not from the result of the arithmetic. For calorimetry: if the solution temperature rises, the reaction is exothermic and delta H is negative; write that first. For electrochemistry: if the cell is galvanic, E cell is positive and delta G is negative; write both before substituting into the Nernst or Gibbs equation. Per the 2024 Chief Reader Report (Q1 Part e(ii)), the most common error on the calorimetry subpart was reporting a positive molar enthalpy for a reaction that heated the solution. Per the 2024 Chief Reader Report (Q3 Part d), students lost additional points by not connecting the sign of E cell to the sign of delta G, which the rubric requires as a separate statement. Setting the sign before the arithmetic prevents both errors.

   AP Chemistry Chief Reader Reports 2023 (Q3, calorimetry sign) and 2024 (Q1 Part e(ii), Q3 Part d, electrochemistry sign)

5. 05

   Using the wrong moles of reaction in calorimetry enthalpy calculations

   On molar enthalpy calculations, a documented error is using the sum of the moles of both reactants as the denominator instead of the moles of either single equimolar reactant. In the 2024 Q1 calorimetry scenario (equimolar lactic acid and NaOH), students added 0.050 mol lactic acid plus 0.050 mol NaOH to get 0.10 mol and divided, halving the correct answer. For a 1 to 1 stoichiometric reaction in equimolar quantities, the moles of reaction equals the moles of either reactant. Per the 2024 Chief Reader Report, this was the least accessible subpart of Q1.

   AP Chemistry Chief Reader Report 2024 (Q1, Part e(ii))

6. 06

   Misidentifying particle diagrams on titration curve or equilibrium questions

   Particulate diagram subparts require reading the ratio of species in the diagram precisely and mapping it to the correct position on a titration curve or the correct equilibrium condition. Per the 2024 Chief Reader Report (Q1, Parts d(i) and d(ii)), the most common error was interpreting a 2:1 ratio of weak acid to conjugate base as the half equivalence point (1:1 ratio) rather than a point before the half equivalence point. Per the 2025 Chief Reader Report (multiple questions), students are advised to read every particulate diagram before reading the prompt and to treat double and triple bonds as a single electron domain in Lewis structure based diagrams.

   AP Chemistry Chief Reader Reports 2024 (Q1, Parts d(i) and d(ii)) and 2025 (Q4, Q7)

7. 07

   Writing the equilibrium expression on paper before answering a buffer capacity or solubility shift subpart

   On buffer and solubility subparts, write the relevant equilibrium expression (Ka, Kb, or Ksp) explicitly on your answer sheet before you begin the explanation. The act of writing it forces the Le Chatelier argument the rubric requires: you can see the species on the left and right of the arrow, identify which one is being added or removed, and state the direction of the resulting shift. Per the 2023 Chief Reader Report (Q4, methylamine buffer, mean 1.66 of 4, the lowest scoring question that year), responses stated the correct conclusion without the equilibrium argument and earned no credit. Per the 2025 Chief Reader Report (Q1 Part E), the claim that a basic salt dissolves more readily in acid needed the explicit connection between added H3O plus, removal of the anion through protonation, and the resulting rightward shift of the dissolution equilibrium. Writing the equilibrium expression first makes that connection visible and creditable.

   AP Chemistry Chief Reader Reports 2023 (Q4, methylamine buffer) and 2025 (Q1, Part E, solubility in acid)

How to practice AP Chemistry FRQs effectively

Timed reps under exam conditions, then self score against the official guideline line by line.

The highest return practice routine is not reading released FRQs; it is writing answers under timed conditions and then grading yourself point by point against that year's official scoring guideline. The archive above pairs every year with its matching scoring guideline on College Board's site so you can do exactly that. Work one long question in about 25 minutes, score it against the rubric, and write down each point you missed and why. After a few practice sessions the pattern of your losses becomes clear and almost always traces to one of the common errors listed above: a missing unit chain, a sign dropped on an enthalpy, a mechanism described by its observation rather than by its principle. Comparing your phrasing to the sample student responses in the scoring materials shows the exact language Readers credit. Per the 2024 Chief Reader Report, students who have performed the actual lab experiments in class score measurably better on experiment based questions, so hands on calorimetry and acid base titration practice has direct exam payoff.

1. 1

   Read all 7 questions during the first few minutes before writing, identify the subparts where you are most confident, and answer those first to bank secure points early.

2. 2

   Budget roughly 25 minutes per long question and 11 minutes per short question. You can answer in any order, so never let one difficult calculation consume all the time allocated for two easier questions.

3. 3

   Write out the full setup for every calculation, including the equation, the substituted values with units, and the unit algebra cancellation. A correct answer with no work shown earns no points; a setup with a minor arithmetic error still earns the setup point.

4. 4

   On every explanation or justification subpart, state the chemical principle explicitly and connect it to the specific species in the question. Identifying a trend without the mechanism loses the point even when the trend is correct.

5. 5

   Check the algebraic sign on every thermodynamics and electrochemistry answer and write one sentence stating what the sign means physically, for example that a negative delta G means the reaction is thermodynamically favorable under the given conditions.

6. 6

   On acid base titration questions, locate the half equivalence point first (at exactly half the equivalence volume) before reading the pKa. The equivalence point and the half equivalence point are different locations on the curve.

7. 7

   For any question involving a particle diagram, count the species carefully and determine the exact ratio before writing your answer. Misreading a 2:1 ratio as 1:1 is the most documented single error on particulate diagram subparts.

8. 8

   Answer every subpart. There is no penalty for an incorrect attempt, and a partially correct response on every part scores far more than perfect answers on only half the section.

9. 9

   Use the provided equations and constants sheet actively. If a subpart asks you to calculate a quantity, scan the sheet first to confirm you are using the correct form of the equation before substituting values.

10. 10

    On comparison questions that ask about two species, address both species explicitly. Per the 2025 Chief Reader Report, responses discussing only one of the two named compounds lost points even when the analysis of the single compound discussed was correct.

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