What you’ll learn7 learning objectivesChoose one objective for a focused lesson, or study the complete topic.2.3.1Dynamic equilibrium• Forward rate = backward rate (closed system)• Describe physical and chemical systems at equilibriumSyllabus objective2.3.2Equilibrium law• K determined from stoichiometry• Deduce K expressions for homogeneous reactionsSyllabus objective2.3.3Equilibrium constant (K)• Magnitude indicates extent of reaction• Temperature dependent• Kreverse = 1/Kforward• Interpret K << 1, K < 1, K = 1, K > 1, and K >> 1Syllabus objective2.3.4Le Châtelier's principle• Predict effects of changes in concentration, temperature, pressure• Include effects on K and equilibrium compositionSyllabus objective2.3.5(HL)—Reaction quotient (Q)• Non-equilibrium concentrations• Compare Q to K to predict direction• Calculate Q and predict direction toward equilibriumSyllabus objective2.3.6(HL)—Equilibrium calculations• K with initial and equilibrium concentrations• Use small-K approximations; quadratic equations are not expectedSyllabus objective2.3.7(HL)—K and ΔG• Both measure equilibrium position• Calculate ΔG⦵ from ΔG⦵ = −RT ln KSyllabus objective