AP Exam Prep · AP Chemistry

AP Chemistry Unit 7 Practice Test: Equilibrium

Unit 7 explains what happens when forward and reverse reactions balance. You will write and calculate K and Q, predict shifts with Le Châtelier's principle and work with solubility equilibria.

Exam weighting:
7–9%
Questions:
13 multiple choice
Time:
about 17 minutes
Cost:
Free, no sign-up

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Question 1 of 13 · 0 answered

Question 1

Topic 7.1 · Concept check

Which statement is true for a reaction at equilibrium?

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What AP Chem Unit 7 covers

Unit 7, Equilibrium, makes up 7–9% of the multiple-choice section and usually takes ~13–15 class periods. These are the topics in the current course framework, and every question in the test above is tagged with one of them.

  1. 7.1Introduction to Equilibrium
  2. 7.2Direction of Reversible Reactions
  3. 7.3Reaction Quotient and Equilibrium Constant
  4. 7.4Calculating the Equilibrium Constant
  5. 7.5Magnitude of the Equilibrium Constant
  6. 7.6Properties of the Equilibrium Constant
  7. 7.7Calculating Equilibrium Concentrations
  8. 7.8Representations of Equilibrium
  9. 7.9Introduction to Le Châtelier's Principle
  10. 7.10Reaction Quotient and Le Châtelier's Principle
  11. 7.11Introduction to Solubility Equilibria
  12. 7.12Common-Ion Effect

Unit 7 key ideas

Equilibrium is dynamic

At equilibrium the forward and reverse rates are equal, so concentrations stay constant, though they are usually not equal to each other.

K and Q

K uses equilibrium concentrations (or pressures) of gases and aqueous species, raised to their coefficients; pure solids and liquids are left out. Compare Q with K to predict the direction of change.

Manipulating K

Reversing a reaction gives 1/K; multiplying coefficients by n raises K to the power n; adding reactions multiplies their K values.

Le Châtelier and solubility

A stressed system shifts to reduce the stress. Only temperature changes the value of K. Ksp describes slightly soluble salts, and a common ion lowers their solubility.

Common Unit 7 mistakes

  • Including solids or pure liquids in K expressions.
  • Saying adding a reactant changes K (it changes Q).
  • Forgetting to square concentrations for coefficients of 2, as in Ksp for CaF₂.

How to study this unit

  • Use an ICE table for every equilibrium calculation and write the K expression first.
  • For Le Châtelier questions, first state whether Q is now greater or less than K.

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More AP Chemistry practice tests

← Unit 6: ThermochemistryUnit 8: Acids and Bases →

About these questions

StudyCoach wrote these questions for this test. Each one is mapped to a topic in the College Board's current AP Chemistry course framework. Every answer key was also checked by a separate AI review, and any disagreement was rechecked by hand. They have not yet been reviewed by an AP Chemistry teacher. If you think an answer is wrong, email support@studycoach.io.

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