AP® practice test

Free AP® Chemistry Practice Test (2026)

This is a set of 25 original practice questions that follow the official AP® Chemistry course units and their exam weights, each with a short explanation. Every question gives the constants and molar masses it needs, and a scientific calculator is enough for the math.

  • 25 questions
  • 9 topics from the official outline
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The practice test

25 questions

Question 1 of 25Which of the following substances has the highest normal boiling point? (Molar masses are given in g/mol.)
Question 2 of 25For the reaction A + B → products, doubling [A] while [B] is held constant makes the initial rate four times as fast. Doubling [B] while [A] is held constant leaves the initial rate unchanged. Which rate law fits these data?
Question 3 of 25The first four ionization energies of a period 3 element are 738, 1,451, 7,733 and 10,543 kJ/mol. Which element is it?
Question 4 of 25What is the pH of a 0.010 M solution of Ba(OH)₂ at 25 °C?
Question 5 of 25For 2H₂(g) + O₂(g) → 2H₂O(l), 4.0 g of H₂ reacts with 16.0 g of O₂. What is the greatest mass of water that can form? (Molar masses: H₂ 2.0, O₂ 32.0, H₂O 18.0 g/mol)
Question 6 of 25A 4.00 L flask holds 0.50 mol of an ideal gas at 27 °C. What is the pressure? (R = 0.0821 L·atm/(mol·K))
Question 7 of 25For N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH° is negative. Which change, made to a mixture at equilibrium, increases the amount of NH₃ at the new equilibrium?
Question 8 of 25Which of the following molecules is polar?
Question 9 of 25A reaction in a coffee-cup calorimeter warms 50.0 g of water from 22.0 °C to 30.0 °C. How much heat did the reaction release? (Specific heat of water = 4.18 J/(g·°C); assume the water absorbs all the heat.)
Question 10 of 25A reaction has ΔH° = +40 kJ/mol and ΔS° = +100 J/(mol·K). Assuming these values don't change with temperature, when is the reaction thermodynamically favored?
Question 11 of 25S²⁻, Cl⁻, K⁺ and Ca²⁺ all have the same number of electrons. Which has the largest radius?
Question 12 of 25A weak monoprotic acid, HA, has Ka = 1.0 × 10⁻⁵. What is the pH of a 0.10 M solution of HA?
Question 13 of 25A container holds 2.0 mol of N₂ and 3.0 mol of O₂ at a total pressure of 1.5 atm. What is the partial pressure of O₂?
Question 14 of 25A reactant decomposes by a first-order reaction with a half-life of 20 minutes. What fraction of the reactant is left after 60 minutes?
Question 15 of 25When aqueous solutions of AgNO₃ and NaCl are mixed, a white precipitate forms. Which is the net ionic equation?
Question 16 of 25The nitrate ion, NO₃⁻, can be drawn with three resonance structures. What do experiments show about its three N–O bonds?
Question 17 of 2525.0 mL of 2.00 M HCl is diluted with water to a total volume of 200.0 mL. What is the new concentration of HCl?
Question 18 of 25For A(aq) ⇌ B(aq), K = 4.0 at a certain temperature. A mixture at that temperature has [A] = 1.0 M and [B] = 2.0 M. Which statement is correct?
Question 19 of 25A buffer contains 0.10 M acetic acid (pKa = 4.74) and 0.010 M sodium acetate. What is its pH?
Question 20 of 25Samples of H₂ gas and O₂ gas are at the same temperature. Which statement is correct?
Question 21 of 25Use these average bond enthalpies to estimate ΔH for H₂(g) + Cl₂(g) → 2HCl(g): H–H 436 kJ/mol, Cl–Cl 243 kJ/mol, H–Cl 431 kJ/mol.
Question 22 of 25A compound is 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass, and its molar mass is 180 g/mol. What is its molecular formula? (Molar masses: C 12.0, H 1.0, O 16.0 g/mol)
Question 23 of 25A 0.020 M solution of a dye has an absorbance of 0.40. A solution of the same dye of unknown concentration, measured in the same cuvette at the same wavelength, has an absorbance of 0.30. What is its concentration?
Question 24 of 25A solution of acetic acid, a weak acid, is titrated with NaOH. Which best describes the pH at the equivalence point?
Question 25 of 25A galvanic cell is built from a Zn/Zn²⁺ half-cell (E° = −0.76 V) and a Cu/Cu²⁺ half-cell (E° = +0.34 V), with standard reduction potentials shown. Which is correct for the cell under standard conditions?

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