AP Chemistry · Key concepts
The AP Chem cheat sheet: every concept the exam keeps coming back to.
Quantitative reasoning · Particle-level explanation · Lab interpretation — what the rubric is really testing.
days until your AP Chem exam
Tue, May 5 · Morning session
Quant
Quantitative reasoning
Stoichiometry & limiting reactants
Mole ratios are the backbone of half the FRQ section.
Equilibrium (K, Q, ICE tables)
Compare Q to K to predict shift; use ICE for concentrations.
Acid-base & pH calculation
Strong vs. weak. Buffers. Henderson-Hasselbalch when asked.
Thermodynamics (ΔH, ΔS, ΔG)
Sign tells you spontaneity; magnitude tells you size of effect.
Concepts
Particle-level explanation
Periodic trends
Effective nuclear charge + shielding explain almost every trend.
Intermolecular forces
London < dipole-dipole < H-bonding. Predict boiling point and solubility.
Bonding (ionic, covalent, metallic)
Bond type controls melting point, conductivity, and solubility.
Kinetics & rate laws
Rate ∝ [A]^m[B]^n. Order is determined experimentally, not from coefficients.
Lab
Reading lab data
Titration curves
Equivalence point, half-equivalence (= pKa), buffer region.
Spectroscopy & Beer's Law
Absorbance ∝ concentration. Slope of A vs. c equals εL.
Identify experimental error
Random vs. systematic. Always tie it to a measurable quantity.
Justify with chemistry, not vocab
'Because Le Chatelier' isn't enough — name the species and the shift.
Exam at a glance · 3 hours 15 minutes
60 MCQs · 90 min
Move steady; mark long calcs.
3 Long FRQs · 60 min
~20 min each, math + explanation.
4 Short FRQs · 45 min
~11 min, precision over volume.
FRQs = 50% · of score
Long FRQs carry the most.
What AP Chem readers actually reward
Three FRQ habits that turn correct chemistry into rubric points.
Rubric move
Show setup with units
Half the calculation point comes from the dimensional analysis. Skipping units forfeits it even when the answer is right.
Weak
moles = 0.045
Scoring-ready
moles HCl = 0.025 L × 1.8 mol/L = 0.045 mol
Rubric move
Particle-level reasoning
Conceptual FRQs reward explaining what the molecules are doing — not just naming the macroscopic phenomenon.
Weak
NaCl conducts when molten because it has ions.
Scoring-ready
When molten, the Na⁺ and Cl⁻ ions are free to move, allowing them to carry charge through the liquid — solid NaCl locks the ions in a lattice.
Rubric move
Cite the data line first
Lab FRQs want: name the data feature (steepness, equivalence point), THEN make the chemistry claim.
Weak
It's a strong acid.
Scoring-ready
The titration curve has a steep, vertical jump near pH 7 and an equivalence point pH ≈ 7, indicating a strong acid–strong base reaction.
Want to see exactly which FRQ row you're losing points on?
Spot the concept
These are the concepts behind a real AP Chem stem.
Three mini MCQs from the exam's most common skill areas. Tap to reveal the answer.
How many grams of H₂O are produced when 16.0 g of CH₄ completely combusts? CH₄ + 2O₂ → CO₂ + 2H₂O (molar masses: CH₄ = 16, H₂O = 18).
- A9.0 g
- B18 g
- C36 g
- D72 g
Which change will shift the equilibrium toward more NH₃?
- AIncrease the temperature.
- BDecrease the total pressure (increase volume).
- CRemove N₂.
- DIncrease the total pressure (decrease volume).
What is the concentration of the acid?
- A0.040 M
- B0.080 M
- C0.100 M
- D0.125 M
Will you score the 5?
Write one timed FRQ. See exactly where rubric points would slip — while there's still time to fix it.
Quick questions
Equilibrium (Unit 7), kinetics (Unit 5), and acids/bases (Unit 8) together cover roughly 40% of the exam and feed almost every long FRQ. Drill these three before broader review.
Always cite the data feature before making the chemistry claim. 'The graph shows X, so the chemistry must be Y' beats jumping straight to the answer.
Critical. The setup point and a portion of the calculation point depend on visible dimensional analysis. A bare numerical answer almost always loses one rubric point.
60 MCQs. 7 FRQs. The 5 lives in the explanation lines.
Or if you want a schedule.