AP Chemistry 3-Day Cram Plan

You have three days until the AP Chemistry exam. This is not the time to memorize the periodic table — it's time to drill the 20-30% of the exam that repeats every year and lock in the FRQ patterns that always appear.

This plan assumes ~4 focused hours per day. Skip nothing on the checklist; if you're short on time, shorten the practice sets, not the topic coverage.

Day 1: Equilibrium and ICE Tables (4 hrs)

Equilibrium accounts for roughly 20-25% of your exam score. This is non-negotiable.

What to review (90 min)

• Equilibrium constants: $K_c$ (concentration-based) vs $K_p$ (pressure-based). Know the relationship: $K_p = K_c (RT)^{\Delta n}$.
• ICE table setup: Initial, Change, Equilibrium. Master the $-x$, $+x$ pattern — students mess this up constantly.
• Le Chatelier's Principle: shifts when you change temperature, pressure, concentration, or volume.
• Solubility equilibria: $K_{sp}$ and the difference between $Q$ and $K_{sp}$.
• Gas-phase equilibria: partial pressures, mole ratios, and calculating $K_p$ from $K_c$.

What to practice (2.5 hrs)

• 15 equilibrium MCQs (strong mix of $K_c$ calculations and Le Chatelier predictions).
• 1 full FRQ: given initial concentrations and $K_c$, calculate equilibrium concentrations using an ICE table.

💡 Highest leverage: ICE tables appear on ~80% of AP Chem FRQs. If you drill 10 ICE tables today, you earn 8-10 easy points on exam day.

Day 2: Acids, Bases, and Buffers (4 hrs)

This unit covers 12-15% of the exam and is heavily FRQ-weighted.

What to review (90 min)

• pH and strong acids/bases: $pH = -\log [H^+]$, $pOH = -\log [OH^-]$, $pH + pOH = 14$.
• Weak acid equilibrium: $K_a = \frac{[H^+][A^-]}{[HA]}$. Know when to use ICE vs. the approximation $[H^+] \approx \sqrt{K_a \cdot C}$.
• Buffers and Henderson-Hasselbalch: $pH = pK_a + \log \frac{[A^-]}{[HA]}$ — this formula is on the exam sheet.
• Titration curves: recognize inflection point (equivalence), buffer region, and steep part.
• Polyprotic acids: $H_2CO_3$ and $H_3PO_4$ have multiple $K_a$ values; use $K_{a1}$ for initial pH.

What to practice (2.5 hrs)

• 15 acid-base MCQs (pH calculations, $K_a$ problems, buffer pH).
• 1 full FRQ on calculating buffer pH or interpreting a titration curve.

⚠️ FRQ trap: When asked to calculate buffer pH, you MUST use Henderson-Hasselbalch or ICE with $K_a$. Averaging $pK_a$ is wrong. Show every step.

Day 3: Thermodynamics and Spontaneity (4 hrs)

Thermodynamics + Gibbs free energy represent ~12-15% of your score.

What to review (90 min)

• Enthalpy, entropy, Gibbs free energy: $\Delta G = \Delta H - T\Delta S$.
• Spontaneity: $\Delta G < 0$ is spontaneous. Know how temperature, $\Delta H$, and $\Delta S$ affect whether a reaction goes.
• Linking $\Delta G$ and $K$: $\Delta G = -RT \ln K$ — if $K > 1$, then $\Delta G < 0$.
• Calorimetry: $q = mc\Delta T$ and Hess's Law.
• Activation energy tie-in: $\Delta G$ tells you if a reaction is possible; activation energy tells you how fast.

What to practice (2.5 hrs)

• 15 thermodynamics MCQs (calculating $\Delta G$, predicting spontaneity, interpreting $\Delta H$ and $\Delta S$ signs).
• 1 full FRQ: calculate $\Delta G$ at a non-standard temperature or determine $\Delta H$ and $\Delta S$ from data and predict spontaneity.

🎯 Exam pattern: Nearly every FRQ combines thermodynamics + equilibrium. Practice linking $\Delta G$, $K$, and equilibrium position.

What this 3-day plan hits hardest

• Equilibrium + ICE tables (40% of your time)
• Acid-base + buffers (30% of your time)
• Thermodynamics and $\Delta G$ (30% of your time)

These three units account for ~50% of the exam. Master them and you're in strong position for a 4 or 5.

What this plan deliberately skips

You will not thoroughly study kinetics, PES, VSEPR, or electrochemistry in 3 days. If weak:

• Kinetics: Skim rate law determination from initial rates (1 example). Accept 3-5 point loss.
• Molecular structure: Know Lewis + formal charge + VSEPR for H₂O, NH₃, CO₂. Draw 3 examples.
• PES: Higher binding energy = inner-shell electrons. Memorize pattern for 2-3 elements.
• Electrochemistry: Skip unless time permits. Focus on $\Delta G$ vs $E$.

The night before

Skim our last-minute review checklist. Sleep 8 hours — a tired brain confuses $K_c$ and $K_p$.

Common point-leaks

• Writing $K_c$ but forgetting pure solids and liquids are not included.
• In ICE tables, using moles instead of molarity for $K_c$.
• Forgetting the $-x$ in ICE tables and solving the wrong equation.
• Confusing equivalence point with half-equivalence point on titration curves.
• Writing $\Delta G = \Delta H - T\Delta S$ but forgetting temperature must be in Kelvin.

Ready to start?

Browse AP Chemistry topics → and drill your first ICE table. Focus beats breadth. You've got this.