• 49 questions

AP Chemistry Stoichiometry Practice Test

Unofficial AP Chemistry stoichiometry practice: moles, mole ratios, limiting reactants, solution and gas stoichiometry, and titration.

Ammonia forms by N₂(g) + 3 H₂(g) → 2 NH₃(g). How many moles of NH₃ can form from 6.0 mol of H₂ and excess N₂?

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Unofficial practice questions, not affiliated with the College Board. Bank checked October 11, 2026.

Next step AP Chemistry Unit 1: moles and atomsAP Chemistry Unit 4 practice test

All 49 questions

Topic 1.1: Moles and molar mass 8

  • Four samples each have a mass of 10.0 g: helium (4.00 g/mol), carbon (12.01 g/mol), aluminum (26.98 g/mol) and iron (55.84 g/mol). Which sample holds the most atoms? Wikipedia, "Mole (unit)"; course topic 1.1
  • How many hydrogen atoms are in 0.100 mol of CH₄? (Avogadro's number is 6.022 × 10²³ per mole.) Wikipedia, "Mole (unit)"; course topic 1.1
  • How many molecules are in 0.500 mol of CO₂? (Avogadro's number is 6.022 × 10²³ per mole.) Wikipedia, "Mole (unit)"; course topic 1.1
  • How many moles of chloride ions are in 0.30 mol of CaCl₂? Wikipedia, "Mole (unit)"; course topic 1.1
  • How many moles of water are in 36.0 g of H₂O (18.02 g/mol)? Wikipedia, "Mole (unit)"; course topic 1.1
  • One molecule of carbon dioxide has an average mass of 44.01 amu. What is the mass of 1 mol of carbon dioxide? College Board, AP Chemistry course description, essential knowledge 1.1.A.3; course topic 1.1
  • What is the mass of 0.250 mol of CaCO₃ (100.09 g/mol)? Wikipedia, "Mole (unit)"; course topic 1.1
  • What is the mass of 1.50 × 10²³ molecules of O₂ (32.00 g/mol)? (Avogadro's number is 6.022 × 10²³ per mole.) Wikipedia, "Mole (unit)"; course topic 1.1
Show all 49 questions (41 more)

Topic 4.5: Mole ratios and mass to mass 10

  • Aluminum is in excess in 2 Al(s) + 6 HCl(aq) → 2 AlCl₃(aq) + 3 H₂(g). A student uses 0.60 mol of HCl in place of 0.30 mol. How does the amount of H₂ change? Wikipedia, "Stoichiometry", Molar proportion; course topic 4.5
  • Ammonia forms by N₂(g) + 3 H₂(g) → 2 NH₃(g). How many moles of NH₃ can form from 6.0 mol of H₂ and excess N₂? Wikipedia, "Stoichiometry", Molar proportion; course topic 4.5
  • Ethane burns by 2 C₂H₆(g) + 7 O₂(g) → 4 CO₂(g) + 6 H₂O(g). How many moles of CO₂ form when 3.0 mol of C₂H₆ burns in excess oxygen? Wikipedia, "Stoichiometry", Molar proportion; course topic 4.5
  • Hydrogen peroxide decomposes by 2 H₂O₂(aq) → 2 H₂O(l) + O₂(g). A sample of 68.0 g decomposes completely and 36.0 g of water forms. What mass of oxygen gas forms? Wikipedia, "Conservation of mass"; course topic 4.5, essential knowledge 4.5.A.1
  • In a blast furnace, Fe₂O₃(s) + 3 CO(g) → 2 Fe(l) + 3 CO₂(g). What mass of iron (55.84 g/mol) forms from 79.84 g of Fe₂O₃ (159.68 g/mol)? Wikipedia, "Stoichiometry", Determining amount of product; course topic 4.5
  • Iron rusts by 4 Fe(s) + 3 O₂(g) → 2 Fe₂O₃(s). How many moles of O₂ react with 2.0 mol of Fe? Wikipedia, "Stoichiometry", Molar proportion; course topic 4.5
  • Methane burns by CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g). What mass of water (18.02 g/mol) forms when 8.00 g of CH₄ (16.04 g/mol) burns completely? Wikipedia, "Stoichiometry", Determining amount of product; course topic 4.5
  • Potassium chlorate decomposes by 2 KClO₃(s) → 2 KCl(s) + 3 O₂(g). What mass of O₂ (32.00 g/mol) forms from 24.5 g of KClO₃ (122.55 g/mol)? Wikipedia, "Stoichiometry", Determining amount of product; course topic 4.5
  • Sodium reacts with chlorine by 2 Na(s) + Cl₂(g) → 2 NaCl(s). What mass of sodium (22.99 g/mol) is needed to make 11.69 g of NaCl (58.44 g/mol)? Wikipedia, "Stoichiometry"; course topic 4.5, essential knowledge 4.5.A.1
  • Sulfur dioxide is oxidized by 2 SO₂(g) + O₂(g) → 2 SO₃(g). What mass of O₂ (32.00 g/mol) reacts with 128.1 g of SO₂ (64.07 g/mol)? Wikipedia, "Stoichiometry", Molar proportion; course topic 4.5, essential knowledge 4.5.A.2

Topic 4.5: Limiting reactant 8

  • A burner is fed 3.0 mol of CH₄ and 4.0 mol of O₂. They react by CH₄ + 2 O₂ → CO₂ + 2 H₂O until one runs out. How much CH₄ is left over? Wikipedia, "Limiting reagent"; course topic 4.5
  • A mixture holds 3.0 mol of Al and 4.0 mol of Cl₂. They react by 2 Al + 3 Cl₂ → 2 AlCl₃. Which reactant limits? Wikipedia, "Limiting reagent"; course topic 4.5
  • A reactor is charged with 4.0 mol of SO₂ and 1.5 mol of O₂, which react by 2 SO₂ + O₂ → 2 SO₃. Which reactant limits, and how much SO₃ can form? Wikipedia, "Limiting reagent"; course topic 4.5
  • A sealed box holds 6 molecules of H₂ and 4 molecules of O₂. They react completely by 2 H₂ + O₂ → 2 H₂O. What does the box hold afterward? Wikipedia, "Limiting reagent"; course topic 4.5
  • By Mg(s) + 2 HCl(aq) → MgCl₂(aq) + H₂(g), 0.10 mol of Mg in acid holding 0.50 mol of HCl gives 0.10 mol of H₂. The run is repeated with 1.0 mol of HCl. How much H₂ forms? Wikipedia, "Limiting reagent"; course topic 4.5
  • In a reaction mixture, which reactant is the limiting reactant? Wikipedia, "Limiting reagent"; course topic 4.5
  • Sodium and chlorine react by 2 Na(s) + Cl₂(g) → 2 NaCl(s). What mass of NaCl (58.44 g/mol) can form from 4.60 g of Na (22.99 g/mol) and 3.55 g of Cl₂ (70.90 g/mol)? Wikipedia, "Limiting reagent"; course topic 4.5
  • Zinc and sulfur react by Zn(s) + S(s) → ZnS(s). A mixture holds 10.0 g of zinc (65.4 g/mol) and 10.0 g of sulfur (32.07 g/mol). Which reactant limits? Wikipedia, "Limiting reagent"; course topic 4.5

Topics 3.7 and 4.5: Solution stoichiometry 9

  • Barium sulfate precipitates by BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2 NaCl(aq). What mass of BaSO₄ (233.40 g/mol) forms when excess Na₂SO₄ is added to 100. mL of 0.150 M BaCl₂? Wikipedia, "Stoichiometry"; course topic 4.5, essential knowledge 4.5.A.3
  • How many moles of HCl are in 25.0 mL of 0.200 M HCl? Wikipedia, "Molar concentration"; course topic 3.7
  • Hydrochloric acid reacts with sodium carbonate by 2 HCl(aq) + Na₂CO₃(s) → 2 NaCl(aq) + H₂O(l) + CO₂(g). What volume of 0.500 M HCl reacts with 2.65 g of Na₂CO₃ (105.99 g/mol)? Wikipedia, "Stoichiometry"; course topic 4.5
  • Lead(II) iodide precipitates by Pb(NO₃)₂(aq) + 2 KI(aq) → PbI₂(s) + 2 KNO₃(aq). How many moles of PbI₂ form when 50.0 mL of 0.100 M Pb(NO₃)₂ is mixed with 50.0 mL of 0.100 M KI? Wikipedia, "Limiting reagent"; course topic 4.5
  • Sodium sulfate dissolves as Na₂SO₄(s) → 2 Na⁺(aq) + SO₄²⁻(aq). What is the concentration of Na⁺ in 0.20 M Na₂SO₄? Wikipedia, "Molar concentration"; course topic 3.7
  • What is the molarity of a solution that holds 0.250 mol of NaCl in 0.500 L of solution? Wikipedia, "Molar concentration"; course topic 3.7
  • What mass of NaOH (40.00 g/mol) is needed to make 250. mL of 0.100 M NaOH? Wikipedia, "Molar concentration"; course topic 3.7
  • Which statement describes a solution, as opposed to a heterogeneous mixture? College Board, AP Chemistry course description, essential knowledge 3.7.A.1; course topic 3.7
  • Zinc dissolves in acid by Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g). What mass of zinc (65.4 g/mol) reacts with 200. mL of 0.300 M HCl? Wikipedia, "Stoichiometry"; course topic 4.5

Topic 4.5: Gas stoichiometry 5

  • Carbon monoxide burns by 2 CO(g) + O₂(g) → 2 CO₂(g). At the same temperature and pressure, what volume of O₂ reacts with 5.0 L of CO? Wikipedia, "Ideal gas law"; course topic 4.5
  • Hydrogen peroxide decomposes by 2 H₂O₂(aq) → 2 H₂O(l) + O₂(g). What volume of O₂ at 300. K and 1.00 atm forms from 3.40 g of H₂O₂ (34.01 g/mol)? (R = 0.08206 L·atm/(mol·K)) Wikipedia, "Ideal gas law"; course topic 4.5
  • Sodium azide decomposes by 2 NaN₃(s) → 2 Na(s) + 3 N₂(g). What volume of N₂ at 298 K and 1.00 atm forms from 0.200 mol of NaN₃? (R = 0.08206 L·atm/(mol·K)) Wikipedia, "Ideal gas law"; course topic 4.5, essential knowledge 4.5.A.3
  • Solid carbon burns completely by C(s) + O₂(g) → CO₂(g) in a sealed, rigid vessel of oxygen, and the vessel returns to its first temperature. How does the gas pressure compare with the start? Wikipedia, "Ideal gas law"; course topic 4.5
  • Zinc reacts with excess acid by Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g), and 0.500 L of H₂ is collected at 273 K and 1.00 atm. What mass of zinc (65.4 g/mol) reacted? (R = 0.08206 L·atm/(mol·K)) Wikipedia, "Ideal gas law"; course topic 4.5

Topic 4.6: Titration 9

  • A 0.250 g sample of a solid acid with one acidic hydrogen is dissolved and titrated. It takes 20.0 mL of 0.100 M NaOH to reach the equivalence point. What is the molar mass of the acid? Wikipedia, "Titration"; course topic 4.6
  • A 15.0 mL sample of 0.200 M HNO₃ is titrated with 0.100 M KOH: HNO₃ + KOH → KNO₃ + H₂O. At what volume of added KOH does the equivalence point come? Wikipedia, "Equivalence point"; course topic 4.6
  • A 25.0 mL sample of Ca(OH)₂ solution is neutralized by 15.0 mL of 0.200 M HCl: Ca(OH)₂ + 2 HCl → CaCl₂ + 2 H₂O. What is the concentration of the Ca(OH)₂? Wikipedia, "Equivalence point"; course topic 4.6
  • A flask holds 25.0 mL of 0.100 M HCl. A student adds 10.0 mL of 0.100 M NaOH. How many moles of HCl have not yet reacted? Wikipedia, "Titration"; course topic 4.6
  • Before a titration, the flask that will hold the acid sample is rinsed with distilled water and left wet. How does this affect the volume of base needed to reach the equivalence point? Wikipedia, "Equivalence point"; course topic 4.6
  • Hydrochloric acid is titrated with sodium hydroxide. Which statement is true at the equivalence point? Wikipedia, "Equivalence point"; course topic 4.6
  • In a titration, what is the analyte? Wikipedia, "Titration"; course topic 4.6
  • Iron(II) is titrated with permanganate: MnO₄⁻ + 5 Fe²⁺ + 8 H⁺ → Mn²⁺ + 5 Fe³⁺ + 4 H₂O. The equivalence point is reached when 0.00200 mol of MnO₄⁻ has been added. How many moles of Fe²⁺ were in the sample? Wikipedia, "Equivalence point"; course topic 4.6
  • Sulfuric acid is titrated by H₂SO₄(aq) + 2 NaOH(aq) → Na₂SO₄(aq) + 2 H₂O(l). A 20.0 mL sample of the acid needs 30.0 mL of 0.100 M NaOH to reach the equivalence point. What is the concentration of the acid? Wikipedia, "Equivalence point"; course topic 4.6

How this list was compiled: Our own questions, written to the stoichiometry topics of the College Board's AP Chemistry Course and Exam Description, effective fall 2024, https://apcentral.collegeboard.org/media/pdf/ap-chemistry-course-and-exam-description.pdf, read 2026-10-11: topic 4.5 (Stoichiometry) and topic 4.6 (Introduction to Titration) of Unit 4, with the two topics they rest on, 1.1 (Moles and Molar Mass) and 3.7 (Solutions and Mixtures). Every equation was checked for balance and every calculated answer was worked a second time from the numbers in the question on 2026-10-11. Molar masses come from the atomic masses in the PubChem periodic table of the National Library of Medicine, https://pubchem.ncbi.nlm.nih.gov/periodic-table/. The rule behind each answer was read on 2026-10-11 in the Wikipedia article named under the question. Licence: Own work.

How it works

This AP Chemistry stoichiometry practice test has 49 questions of our own, from mole ratios to titration, each with a worked answer. It is unofficial and not affiliated with or endorsed by the College Board, which owns AP.

Read the full guide

What the test covers

Stoichiometry is topic 4.5 of Unit 4 in the College Board's course description for fall 2024, read October 11, 2026, and titration is topic 4.6. The bank has six sets: mole ratios and mass to mass (10 questions), limiting reactant (8), solution stoichiometry with molarity from topic 3.7 (9), gas stoichiometry (5), titration (9), and moles and molar mass from topic 1.1 (8). The split is ours.

How answers were checked

Every equation was checked for balance, and every calculated answer was worked a second time from the numbers in the question. Molar masses come from the PubChem periodic table.

  • Go through moles every time: grams or liters to moles, the mole ratio, then back out.
  • For a limiting reactant, divide each amount in moles by its coefficient. The smallest result runs out first.
  • Carry extra digits to the end and round once.

Questions and answers

What unit is stoichiometry in AP Chemistry?

Unit 4, Chemical Reactions, as topic 4.5, with titration as topic 4.6. The College Board's course page puts Unit 4 at 7 to 9% of the multiple-choice section. The mole is topic 1.1 and molarity is topic 3.7.

Does this AP Chem practice test cover solution stoichiometry?

Yes. One set of nine covers molarity and reactions in solution, such as precipitation, and nine more questions are titrations. Pick either set in the Start from menu to practice it alone.

Is percent yield on this stoichiometry test?

No. The course description does not name percent yield, so no question asks for it. The limiting reactant questions stop at the greatest amount of product that can form.

Do I need a periodic table for these questions?

No. Each question prints the molar masses it needs and gives the gas constant where it is used. A calculator helps.

Are these real AP Chemistry exam questions?

No. The College Board owns the real questions, and none appears here even in other words. Every question on this page was written for it from the topic statements and the public sources named.

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