AP Chemistry
AP Chemistry FRQ Tips: How to Write Answers That Actually Score
days until your AP Chem exam
Tue, May 5 · Morning session
How the AP Chem FRQ points are scored
Three long-form FRQs (~10 points each) test mechanisms, equilibrium, and lab analysis. Four short-form FRQs (~4 points each) test specific concept application. Particulate diagrams and algebraic setup are point-earners.
Points per FRQ type
Suggested time budget · 105 min
Long FRQ 1
10 pt · 22 minLong-form experimental / lab analysis with calculation, particulate diagram, and justification.
Long FRQ 2–3
20 pt · 44 minEquilibrium / kinetics / thermodynamics with multi-step calculations and reasoning.
Short FRQs (×4)
16 pt · 39 minShorter concept-application prompts on a single topic.
Exam composite weighting
7 FRQs carry the same weight as 60 MCQs
Decode the task word before you write
Every AP FRQ begins with a task word. It tells you the minimum sentence type required for the point. Writing too much costs time; writing the wrong kind costs the point outright.
Want to know if you're actually doing this?
Write one AP Chem FRQ. Get your setup, calculation, and justification scored against the real rubric.
Weak vs. strong: equilibrium with Le Chatelier
Equilibrium prompts reward direction + reason. Readers want the shift AND the mechanism from Q vs. K or concentration change.
Prompt
For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH < 0. The system is at equilibrium. The temperature is increased. Predict the effect on the equilibrium concentration of NH₃ and justify your answer.
Weak answer
"When you heat up the reaction, it shifts backward, so less NH₃ is made."
Why it lost points
- No mention of Le Chatelier or the exothermic nature of the forward reaction.
- 'Heat' is not treated as a product - missing the mechanism.
- Does not connect to the equilibrium constant K.
Strong answer
"Because ΔH < 0, the forward reaction releases heat, so heat can be treated as a product: N₂ + 3H₂ ⇌ 2NH₃ + heat. Adding thermal energy shifts the equilibrium toward the reactants by Le Chatelier's principle, decreasing [NH₃]. Equivalently, K decreases with temperature for an exothermic reaction because the reverse rate grows faster than the forward rate."
Why it scores full marks
- Names Le Chatelier and treats heat as a product - the textbook mechanism.
- Links the shift to both the stress (added heat) and the sign of ΔH.
- Bonus reasoning with K - shows the student understands why, not just what happens.
Weak vs. strong: stoichiometry short FRQ
Short FRQs usually ask for a setup + numerical answer. The setup matters: readers award credit even when the final number is slightly off if the work is right.
Prompt
A 5.00 g sample of CaCO₃ is decomposed. Calculate the mass of CO₂ produced. (Molar masses: CaCO₃ = 100.09 g/mol, CO₂ = 44.01 g/mol)
Weak answer
"5.00 × 44 / 100 = 2.2 g CO₂"
Why it lost points
- Skips the balanced equation and the mole conversion - no reasoning shown.
- Uses 44 and 100 instead of the given molar masses, losing precision.
- No units on intermediate steps - reader can't follow the logic.
Strong answer
"CaCO₃(s) → CaO(s) + CO₂(g). Moles CaCO₃ = 5.00 g ÷ 100.09 g/mol = 0.04996 mol. From the 1:1 mole ratio, moles CO₂ = 0.04996 mol. Mass CO₂ = 0.04996 mol × 44.01 g/mol = 2.20 g."
Why it scores full marks
- Balanced equation first - anchors the mole ratio.
- Explicit step-by-step conversion with units at every stage.
- Final answer to correct sig figs, matching the given data.
What you see in GradGPT
This is what your feedback looks like
Every Chem FRQ you write gets scored against the same rubric AP readers use. Strengths, improvements, and notes are highlighted inline - on your sentences, not in a generic rubric summary.
Your response
Heat shifts the reaction backwards. This is because the forward reaction is exothermic. So the equilibrium moves to the left and less NH₃ is made. This is Le Chatelier's principle.
Inline feedback
Rubric breakdown
You scored higher than 58% of students on this prompt
Task word addressed
1/1
"Justify" answered with reasoning
Mechanism / principle
1/2
Le Chatelier mentioned but not applied early
Connection to K or stoichiometry
0/1
No reference to the equilibrium constant
Get this on your own answer.
The 5 FRQ patterns that cover AP Chem
Every AP Chem FRQ fits one of these five patterns. Recognize the pattern; know the moves.
Equilibrium / Le Chatelier
K, Q, or ICE table prompts. Readers want direction, mechanism, and the principle tied to a specific quantity.
- Write the equilibrium expression or ICE table before reasoning.
- Treat heat as a product or reactant explicitly when thermal stress is applied.
Stoichiometry calculation
Mass → moles → moles → mass. Every conversion is a point.
- Write the balanced equation first.
- Track units at every step - a skipped unit is a lost point.
Particulate diagram / model
Draw what's happening at the molecular level - different colors for different species, correct ratios.
- Use the stoichiometric ratio from the balanced equation, not your intuition.
- Label at least one species explicitly.
Lab analysis with error
Given a procedure and data, evaluate a student's work. Readers want a specific flaw AND a correction.
- Name the specific step that introduces error.
- Predict whether the result would be high or low, with reasoning.
Justify a claim with a principle
'Justify using coulombic attraction' or '...using VSEPR.' The named principle must actually appear in your answer.
- State the named principle in your first sentence.
- Apply it with a specific numerical or structural detail.
The mistakes that quietly cost points
These show up every year. Each one is a single habit - fix the habit and you bank points you were already close to earning.
Skipping the balanced equation on stoichiometry prompts. The balanced equation is often a scoring row on its own.
Writing 'shifts right' without naming the stress. Readers want stress → response → reason, not just the direction.
Using 'denatured,' 'activated,' or 'Le Chatelier' as a one-word answer. Name the principle AND apply it.
Leaving units off intermediate steps. 0.05 with no unit loses credit even when the final answer is right.
Drawing particulate diagrams with wrong ratios. Match the stoichiometry, not what looks balanced.
Running out of time on short FRQs. They're fast - don't write a long FRQ's worth of sentences for 2 points.
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scored a 5
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Your first FRQ scored against the real AP Chem rubric.
Frequently Asked Questions
Seven. Three long-form (~10 points each) and four short-form (~4 points each). You get 105 minutes total - roughly 22 minutes per long FRQ and 10 minutes per short FRQ.
Equilibrium, kinetics, and acid-base are on nearly every exam. Thermodynamics and electrochemistry rotate. Particulate diagrams have appeared on every exam since 2014.
When asked, yes - and readers award credit for correctly showing lone pairs and formal charge. If a prompt doesn't ask for a drawing, describing the geometry in words is enough.
Strict enough that losing a sig fig can cost a point on the final numeric answer. Match the number of sig figs in the given data - don't round mid-calculation.
Skipping the setup. Readers award credit for the balanced equation, the mole conversion, the ICE table - not just the final number. Show the work that would let a grader follow your logic.
50/50. Seven FRQs carry the same weight as 60 multiple-choice questions. Most students have far more room to grow on FRQs than on MCQs, making FRQ practice the highest-leverage prep.
Write one AP Chem FRQ. See exactly where you lost points.
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