Equilibrium Overview — AP Chemistry
1. Unit at a Glance
This unit builds conceptually from foundational definitions to increasingly complex quantitative calculations and real-world applications. We start with what dynamic equilibrium actually is, then introduce the core metrics Q (reaction quotient) and K (equilibrium constant) that you will use for every type of equilibrium problem.
After mastering general equilibrium rules and Le Châtelier’s principle, we apply these concepts to the specific case of solubility equilibria, a frequently tested topic, before closing by connecting equilibrium back to the free energy concepts you learned in the previous unit.
Common Pitfalls
Why: K only describes the system at equilibrium, while Q describes the system at any point during the reaction
Why: Equilibrium describes the extent of a reaction (thermodynamics), not how fast it proceeds (kinetics)
Why: Exponents in Q and K directly match the coefficients from the balanced reaction equation