AP Chem · Unit 7 Progress Check

AP Chemistry Unit 7 Progress Check Equilibrium walkthrough.

AP Chemistry Unit 7 is equilibrium, and the Unit 7 Progress Check MCQ is built on Q versus K, ICE tables, and Le Châtelier reasoning. This walkthrough covers what each question type tests, the traps, and how to work through them. Explanations only — no AP Classroom answer keys.

Updated August 2026Written by Mahmudul HasanFree · No signup

What Unit 7 covers

Unit 7 is Equilibrium. Equilibrium is roughly 7–9% of the AP Chemistry exam and underpins the acid-base unit that follows.

Dynamic equilibrium

Forward and reverse rates equal, concentrations constant but reactions still occurring.

The equilibrium constant

Writing K from a balanced equation, and why pure solids and liquids are excluded.

Reaction quotient Q

Comparing Q to K to predict which direction a system shifts.

ICE tables

Initial, change, equilibrium — the standard tool for equilibrium calculations.

Le Châtelier’s principle

How concentration, pressure, and temperature changes shift a system.

Solubility equilibria

K_sp, molar solubility, and the common-ion effect.

The Progress Check MCQ: what each question type tests

These are the question patterns that recur on this Progress Check, and what each one is really asking.

Q versus K

If Q is less than K the reaction shifts right; greater than K shifts left. This is the single most common question form.

Le Châtelier prediction

Add a reactant and the system consumes it. Only temperature actually changes the value of K.

Write the K expression

Products over reactants, each raised to its coefficient, with solids and pure liquids omitted.

Pressure changes

Shifts toward the side with fewer moles of gas. Adding an inert gas at constant volume changes nothing.

Common-ion effect

Adding a shared ion decreases solubility — reason it through with Q and K_sp.

The Progress Check FRQ

Unit 7 free response usually asks for an ICE-table calculation followed by a justification. Points come from setting up the table correctly, using the equilibrium expression properly, and explaining a shift in terms of Q relative to K or of Le Châtelier — with the reasoning stated, not implied.

Where students lose the most points

Including solids or pure liquids in K

Their concentrations are constant and are omitted from the expression entirely.

Thinking a catalyst shifts equilibrium

It speeds both directions equally and changes only how fast equilibrium is reached.

Assuming temperature changes behave like concentration changes

Temperature is the only change that alters the value of K itself.

Forgetting coefficients as exponents

Each concentration is raised to its stoichiometric coefficient.

Saying the reaction “stops”

At equilibrium both directions continue at equal rates — it is dynamic, not static.

How to work through this unit

Before predicting any shift, calculate or reason out Q and compare it with K. That single comparison answers most Unit 7 questions without a full ICE table.

Once you have finished the Progress Check, put your raw score into our AP Chemistry Calculator to see roughly where that pace puts you on the 1–5 scale, and use the AP Chemistry Review for the full exam format and study plan.

Frequently asked questions

Quick answers — written by humans, not a chatbot.

What does the AP Chemistry Unit 7 Progress Check cover?

Equilibrium: dynamic equilibrium, writing equilibrium constant expressions, the reaction quotient Q, ICE tables, Le Châtelier’s principle, and solubility equilibria.

What does it mean if Q is less than K?

The system has too many reactants relative to equilibrium, so the reaction shifts to the right, forming more products until Q equals K.

Does a catalyst change the equilibrium position?

No. A catalyst speeds up both the forward and reverse reactions equally, so equilibrium is reached faster but the position and the value of K are unchanged.

Do you publish AP Chemistry Unit 7 answer keys?

No. We publish walkthroughs of the reasoning and the common traps rather than raw AP Classroom answers.