• 72 questions

AP Chemistry Thermochemistry and Thermodynamics Test

Unofficial AP Chem thermodynamics practice test: Unit 6 thermochemistry plus entropy and Gibbs free energy from Unit 9.

A reaction in a beaker makes the solution and the glass feel warmer. How is the reaction classified?

Pick an answer, then press Check answer. Then you see Correct or Not quite, with the reason. Keys: A to D pick, Enter checks.

Print covers the next 25 questions. Share this set copies a link to the same questions in the same order.

More options

Unofficial practice questions, not affiliated with the College Board. Bank checked October 14, 2026.

Next step Rest of Unit 9: electrochemistryUnit 7: AP Chemistry equilibrium

All 72 questions

Topic 6.1: Endothermic and exothermic processes 5

  • A reaction in a beaker makes the solution and the glass feel warmer. How is the reaction classified? College Board, AP Chemistry Course and Exam Description, topic 6.1, essential knowledge 6.1.A.3
  • A student dissolves a white solid in water, and the beaker becomes cold to the touch. How is the dissolving classified? College Board, AP Chemistry Course and Exam Description, topic 6.1, essential knowledge 6.1.A.4
  • In an endothermic reaction, where does the energy gained by the system come from? College Board, AP Chemistry Course and Exam Description, topic 6.1, essential knowledge 6.1.A.3
  • What decides whether the formation of a solution is exothermic or endothermic? College Board, AP Chemistry Course and Exam Description, topic 6.1, essential knowledge 6.1.A.4
  • Which process is endothermic? College Board, AP Chemistry Course and Exam Description, topic 6.1, essential knowledge 6.1.A.2
Show all 72 questions (67 more)

Topic 6.2: Energy diagrams 3

  • The energy diagram of a reaction shows a drop of 85 kJ from reactants to products. What does the diagram of the reverse reaction show? College Board, AP Chemistry Course and Exam Description, topic 6.2, essential knowledge 6.2.A.1; answer worked from the numbers in the question
  • On an energy diagram the products sit lower than the reactants. What kind of process is it? College Board, AP Chemistry Course and Exam Description, topic 6.2, essential knowledge 6.2.A.1
  • On an energy diagram the reactants are at 50 kJ and the products are at 120 kJ. What is the energy change of the reaction? College Board, AP Chemistry Course and Exam Description, topic 6.2, essential knowledge 6.2.A.1; answer worked from the numbers in the question

Topic 6.3: Heat transfer and thermal equilibrium 3

  • A hot metal block is placed against a cold one. At the particle level, what is different about the hot block at first? College Board, AP Chemistry Course and Exam Description, topic 6.3, essential knowledge 6.3.A.1
  • At the particle level, how is energy transferred between two bodies in thermal contact? College Board, AP Chemistry Course and Exam Description, topic 6.3, essential knowledge 6.3.A.2
  • Two bodies in contact reach thermal equilibrium. What is now the same in both? College Board, AP Chemistry Course and Exam Description, topic 6.3, essential knowledge 6.3.A.3

Topic 6.4: Heat capacity and calorimetry 8

  • A 40.0 g sample of an alloy takes in 720. J, and its temperature goes up by 30.0 °C. What is the specific heat of the alloy? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.1; answer worked from the numbers in the question
  • A 75.0 g sample of water is heated from 15.0 °C to 35.0 °C. With 4.18 J/(g·°C) as the specific heat of water, how much heat does the sample take in? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.1; answer worked from the numbers in the question
  • A hot metal sample is dropped into 200. g of water in a calorimeter, and the water warms by 5.00 °C. How much heat did the metal lose? The specific heat of water is 4.18 J/(g·°C). College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.1; answer worked from the numbers in the question
  • A salt dissolves in water in a coffee-cup calorimeter, and the temperature of the mixture rises. What does this show? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.7
  • A solid dissolves in water in a calorimeter. The 50.0 g mixture warms by 2.00 °C, and its specific heat is 4.18 J/(g·°C). What is q for the dissolving process? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.7; answer worked from the numbers in the question
  • A student stirs 150. g of water at 90.0 °C into 50.0 g of water at 10.0 °C inside a calorimeter that loses no heat. Which temperature does the mixture reach? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.2; answer worked from the numbers in the question
  • Equal masses of substance A and substance B absorb the same amount of heat. A warms by 5 °C and B warms by 20 °C. Which has the greater specific heat? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.3
  • What does the first law of thermodynamics state? College Board, AP Chemistry Course and Exam Description, topic 6.4, essential knowledge 6.4.A.2

Topic 6.5: Energy of phase changes 4

  • The enthalpy of vaporization of water is 40.65 kJ/mol. How much energy is released when 2.00 mol of steam condenses? Wikipedia, "Enthalpy of vaporization"; course topic 6.5, essential knowledge 6.5.A.2
  • The molar enthalpy of fusion of ice is 6.01 kJ/mol. How much energy is absorbed when 2.50 mol of ice melts at 0 °C? Wikipedia, "Enthalpy of fusion"; course topic 6.5, essential knowledge 6.5.A.2
  • The molar enthalpy of vaporization of a liquid is +30 kJ/mol. What is its molar enthalpy of condensation? College Board, AP Chemistry Course and Exam Description, topic 6.5, essential knowledge 6.5.A.2
  • What happens to the temperature of a pure substance while it melts? College Board, AP Chemistry Course and Exam Description, topic 6.5, essential knowledge 6.5.A.1

Topic 6.6: Introduction to enthalpy of reaction 4

  • A reaction run at constant pressure has ΔH = −250 kJ. What does the value tell you? College Board, AP Chemistry Course and Exam Description, topic 6.6, essential knowledge 6.6.A.1
  • For 2 H₂(g) + O₂(g) → 2 H₂O(l), ΔH = −572 kJ. How much heat is released when 0.500 mol of H₂ reacts? Wikipedia, "Hess's law"; course topic 6.6, essential knowledge 6.6.A.1
  • For C(graphite) + O₂(g) → CO₂(g), ΔH = −393.5 kJ/mol. How much heat is released when 3.00 mol of graphite burns? Wikipedia, "Hess's law"; course topic 6.6, essential knowledge 6.6.A.1
  • In an exothermic reaction in solution, why does the temperature rise? College Board, AP Chemistry Course and Exam Description, topic 6.6, essential knowledge 6.6.A.3

Topic 6.7: Bond enthalpies 4

  • For X₂(g) + Y₂(g) → 2 XY(g), the average bond enthalpies are X–X 240 kJ/mol, Y–Y 160 kJ/mol and X–Y 300 kJ/mol. What is the estimated ΔH? College Board, AP Chemistry Course and Exam Description, topic 6.7, essential knowledge 6.7.A.2; answer worked from the numbers in the question
  • In a reaction, 900 kJ is needed to break the bonds of the reactants, and 700 kJ is released as the bonds of the products form. How is the reaction classified? College Board, AP Chemistry Course and Exam Description, topic 6.7, essential knowledge 6.7.A.2
  • Is the breaking of a chemical bond endothermic or exothermic? College Board, AP Chemistry Course and Exam Description, topic 6.7, essential knowledge 6.7.A.2
  • Why is a ΔH worked out from bond enthalpies only an estimate? College Board, AP Chemistry Course and Exam Description, topic 6.7, essential knowledge 6.7.A.2

Topic 6.8: Enthalpy of formation 4

  • The values of ΔHf° are −110.5 kJ/mol for CO(g), −286 kJ/mol for H₂O(l) and −393.5 kJ/mol for CO₂(g). What is ΔH° for CO(g) + H₂O(l) → CO₂(g) + H₂(g)? Wikipedia, "Hess's law"; course topic 6.8, essential knowledge 6.8.A.1
  • What is the standard enthalpy of formation of an element in its reference state, such as O₂(g) or graphite? Wikipedia, "Standard enthalpy of formation"; course topic 6.8, essential knowledge 6.8.A.1
  • Which equation is the formation reaction whose enthalpy change is the standard enthalpy of formation of CO₂(g)? Wikipedia, "Standard enthalpy of formation"; course topic 6.8, essential knowledge 6.8.A.1
  • With ΔHf° of −110.5 kJ/mol for CO(g) and −393.5 kJ/mol for CO₂(g), what is ΔH° when 2 mol of CO burns: 2 CO(g) + O₂(g) → 2 CO₂(g)? Wikipedia, "Hess's law"; course topic 6.8, essential knowledge 6.8.A.1

Topic 6.9: Hess's law 5

  • A chemical equation is reversed. What happens to its enthalpy change? College Board, AP Chemistry Course and Exam Description, topic 6.9, essential knowledge 6.9.B.2
  • A reaction has ΔH = −150 kJ. Every coefficient of its equation is multiplied by 3. What is ΔH for the new equation? College Board, AP Chemistry Course and Exam Description, topic 6.9, essential knowledge 6.9.B.2
  • A → B has ΔH = +40 kJ, and B → C has ΔH = −90 kJ. What is ΔH for C → A? College Board, AP Chemistry Course and Exam Description, topic 6.9, essential knowledge 6.9.B.2; answer worked from the numbers in the question
  • Liquid water forms from its elements with ΔH = −286 kJ/mol, and H₂O(l) → H₂O(g) has ΔH = +44 kJ/mol. What is ΔH for H₂(g) + ½ O₂(g) → H₂O(g)? Wikipedia, "Hess's law"; course topic 6.9, essential knowledge 6.9.B.2
  • Why can the enthalpy changes of the steps of a process be added to get the overall enthalpy change? College Board, AP Chemistry Course and Exam Description, topic 6.9, essential knowledge 6.9.B.1

Topic 9.1: Introduction to entropy 5

  • A gas expands into a larger volume at constant temperature. What happens to its entropy? College Board, AP Chemistry Course and Exam Description, topic 9.1, essential knowledge 9.1.A.1
  • For N₂(g) + 3 H₂(g) → 2 NH₃(g), which sign is expected for ΔS, and why? College Board, AP Chemistry Course and Exam Description, topic 9.1, essential knowledge 9.1.A.1; answer worked from the numbers in the question
  • For which reaction is ΔS expected to be positive? College Board, AP Chemistry Course and Exam Description, topic 9.1, essential knowledge 9.1.A.1
  • In which change does a substance end with more entropy than it began with? College Board, AP Chemistry Course and Exam Description, topic 9.1, essential knowledge 9.1.A.1
  • Why does the entropy of a gas increase when its temperature rises? College Board, AP Chemistry Course and Exam Description, topic 9.1, essential knowledge 9.1.A.2

Topic 9.2: Absolute entropy and entropy change 3

  • For 2 X(s) → 2 Y(s) + Z(g), the standard molar entropies are X 50, Y 40 and Z 205 J/(mol·K). What is ΔS° for the reaction? College Board, AP Chemistry Course and Exam Description, topic 9.2, essential knowledge 9.2.A.1; answer worked from the numbers in the question
  • For A(g) + B(g) → C(g), the standard molar entropies are A 200, B 130 and C 240 J/(mol·K). What is ΔS° for the reaction? College Board, AP Chemistry Course and Exam Description, topic 9.2, essential knowledge 9.2.A.1; answer worked from the numbers in the question
  • How is the standard entropy change of a reaction calculated from absolute entropies? College Board, AP Chemistry Course and Exam Description, topic 9.2, essential knowledge 9.2.A.1

Topic 9.3: Gibbs free energy and thermodynamic favorability 10

  • A process absorbs heat (ΔH° > 0) and raises entropy (ΔS° > 0). When is it thermodynamically favored? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.6
  • A process has ΔH° < 0 and ΔS° > 0. At which temperatures is it thermodynamically favored? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.6
  • A process has ΔH° > 0 and ΔS° < 0. At which temperatures is it thermodynamically favored? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.6
  • Find ΔG° at 400. K for a change with ΔH° = −80.0 kJ/mol and ΔS° = −150. J/(mol·K). College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.5
  • For A + B → C, the standard free energies of formation are A −50, B −20 and C −120 kJ/mol. What is ΔG° for the reaction? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.3
  • For a certain change, ΔH° is +36.0 kJ/mol and ΔS° is +120. J/(mol·K). Above which temperature does ΔG° turn negative? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.5
  • The freezing of water releases heat (ΔH° < 0) and lowers entropy (ΔS° < 0). When is it thermodynamically favored? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.4
  • What does a negative ΔG° mean for a process? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.2
  • Which conditions define the standard state behind the symbol ΔG°? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.1
  • Why does the course prefer the phrase "thermodynamically favored" to the word "spontaneous"? College Board, AP Chemistry Course and Exam Description, topic 9.3, essential knowledge 9.3.A.2

Topic 9.4: Thermodynamic and kinetic control 3

  • A favored reaction shows no visible progress after a week. Does that show the system is at equilibrium? College Board, AP Chemistry Course and Exam Description, topic 9.4, essential knowledge 9.4.A.2
  • A reaction has ΔG° < 0, yet no measurable change is seen. What is the most reasonable conclusion? College Board, AP Chemistry Course and Exam Description, topic 9.4, essential knowledge 9.4.A.2
  • What is a common reason that a thermodynamically favored process is under kinetic control? College Board, AP Chemistry Course and Exam Description, topic 9.4, essential knowledge 9.4.A.2

Topic 9.5: Free energy and equilibrium 5

  • A reaction has ΔG° < 0. What is true of its equilibrium constant? College Board, AP Chemistry Course and Exam Description, topic 9.5, essential knowledge 9.5.A.1
  • A reaction has ΔG° = 0. What is its equilibrium constant? College Board, AP Chemistry Course and Exam Description, topic 9.5, essential knowledge 9.5.A.3
  • For a reaction, ΔG° is positive and much larger than RT. What can be said about K? College Board, AP Chemistry Course and Exam Description, topic 9.5, essential knowledge 9.5.A.3
  • The value of ΔG° is −5.70 kJ/mol at 298 K. Taking R as 8.314 J/(mol·K), find the equilibrium constant. College Board, AP Chemistry Course and Exam Description, topic 9.5, essential knowledge 9.5.A.2
  • Which equation relates the standard free energy change to the equilibrium constant? College Board, AP Chemistry Course and Exam Description, topic 9.5, essential knowledge 9.5.A.2

Topic 9.6: Free energy of dissolution 2

  • Which contribution to the free energy of dissolution concerns the solid alone? College Board, AP Chemistry Course and Exam Description, topic 9.6, essential knowledge 9.6.A.1
  • Why is the total free energy change of dissolution hard to predict? College Board, AP Chemistry Course and Exam Description, topic 9.6, essential knowledge 9.6.A.1

Topic 9.7: Coupled reactions 4

  • How can a thermodynamically unfavorable process be made to occur? College Board, AP Chemistry Course and Exam Description, topic 9.7, essential knowledge 9.7.A.1
  • In photosynthesis, carbon dioxide is turned into glucose, an unfavorable change overall. What drives it? College Board, AP Chemistry Course and Exam Description, topic 9.7, essential knowledge 9.7.A.1
  • Reaction 1 has ΔG° = +30 kJ/mol. It is coupled, through a shared intermediate, to reaction 2 with ΔG° = −45 kJ/mol. What is ΔG° for the overall reaction? College Board, AP Chemistry Course and Exam Description, topic 9.7, essential knowledge 9.7.A.2
  • What must two coupled reactions share? College Board, AP Chemistry Course and Exam Description, topic 9.7, essential knowledge 9.7.A.2

How this list was compiled: Our own questions, written to Unit 6 (Thermochemistry, topics 6.1 to 6.9) and to the thermodynamics topics 9.1 to 9.7 of Unit 9 (Thermodynamics and Electrochemistry) 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 2026-10-14. The rule behind each answer was read on 2026-10-14 in the essential knowledge statement of the course description named under the question; the measured values (enthalpies of formation, fusion and vaporization) were read in the Wikipedia articles named. Every calculated answer is worked from the numbers the question prints and was worked out a second time. Licence: Own work. Short quotations from the public documents named under each question.

How it works

This AP Chemistry thermochemistry practice test has 72 multiple-choice questions of our own on Unit 6 and on the thermodynamics topics of Unit 9. It is unofficial and is not affiliated with or endorsed by the College Board, the owner of AP.

Read the full guide

What the two units cover

The College Board's course description, effective fall 2024 and read October 14, 2026, gives Unit 6, Thermochemistry, nine topics, from endothermic and exothermic processes through calorimetry (8 questions here) to Hess's law. Unit 9 opens with seven thermodynamics topics: entropy, Gibbs free energy (10 questions), kinetic control, free energy and equilibrium, dissolution and coupled reactions. No topic is weighted, so the counts are ours.

What is left out

The four electrochemistry topics that end Unit 9 have their own page. The description says the distinction between enthalpy and internal energy and the concept of state functions are not assessed, so neither is asked. Energy diagrams are put into words.

  • Give q a sign before you calculate: heat gained by the water is heat lost by the reaction.
  • In ΔG° = ΔH° − TΔS°, change ΔS° from joules to kilojoules first. Skipping that step gives the classic wrong answer.
  • Products minus reactants works for ΔH°, ΔS° and ΔG°. Bond enthalpies run the other way: broken minus formed.

Questions and answers

Which units of AP Chemistry cover thermochemistry and thermodynamics?

Unit 6, Thermochemistry, and Unit 9, Thermodynamics and Electrochemistry. Each is 7 to 9% of the multiple-choice section, by the College Board's course page. That section has 60 questions in 1 hour 30 minutes.

What should an AP Chemistry thermochemistry study guide cover?

Endothermic and exothermic changes, q = mcΔT and calorimetry, enthalpies of fusion and vaporization, enthalpy of reaction per mole, bond enthalpies, enthalpies of formation and the three rules of Hess's law.

What goes in an AP Chem thermo study guide for Unit 9?

An AP Chemistry thermodynamics study guide needs the sign of ΔS from phase and moles of gas, ΔG° = ΔH° − TΔS° with its four sign cases, ΔG° = −RT ln K, kinetic control and coupled reactions.

Does a negative ΔG° mean a reaction is fast?

No. It means the reaction is thermodynamically favored. A favored reaction with a high activation energy can be too slow to observe, which the course calls kinetic control.

Is this the AP Chemistry Unit 6 Progress Check?

No. Progress Checks are the College Board's own sets, given through AP Classroom. The questions here are our own, written from the published topic lists, and none copies or rewords a real exam question.

More tests

Show 8 more

Browse Civics and Law