The balance point. Dynamic equilibrium and the reaction quotient, the equilibrium constant and its properties, ICE tables, Le Châtelier's principle, and solubility equilibria.
Six ways to master Unit 7 — pick whichever fits how you like to study.
Twelve topics from the College Board CED, in order.
Unit 7 examines what happens when a reversible reaction stops changing on the macroscopic level — not because the reaction has stopped, but because forward and reverse rates have become equal. This is dynamic equilibrium. You'll learn to compare the reaction quotient (Q) to the equilibrium constant (K) to predict which direction a reaction will shift, use ICE tables to calculate equilibrium concentrations, and apply Le Châtelier's principle to predict how a system responds to a stress like a concentration, volume, or temperature change. The unit closes by extending equilibrium concepts to solubility equilibria — the dissolving and precipitating of ionic solids.
This unit is roughly 7–9% of the AP Chem exam and takes about 13–15 class periods, among the longer units in the course. Equilibrium reasoning returns directly in Unit 8 (acid-base equilibria) — mastering Q vs. K comparisons and ICE tables here will make that unit far more manageable.
Two core themes run through this unit: