What you’ll learn17 learning objectivesChoose one objective for a focused lesson, or study the complete topic.3.1.1Brønsted-Lowry theory• Acid = proton donor• Base = proton acceptor• Deduce acid and base in a reaction; distinguish base and alkaliSyllabus objective3.1.2Conjugate acid-base pairs• Differ by one proton• Deduce conjugate acid/base formulasSyllabus objective3.1.3Amphiprotic species• Can act as both acid and base• Write equations showing acid and base behaviourSyllabus objective3.1.4pH scale• pH = −log₁₀[H⁺]• [H⁺] = 10⁻ᵖᴴ• Calculate pH and [H+]; include universal indicator and pH probe useSyllabus objective3.1.5Ion product of water (Kw)• Kw = [H⁺][OH⁻]• Acidic: [H⁺] > [OH⁻]• Neutral: [H⁺] = [OH⁻]• Basic: [H⁺] < [OH⁻]• Recognize acidic, neutral, and basic solutions from [H+] and [OH-]Syllabus objective3.1.6Strong vs. weak acids/bases• Differ in extent of ionization• Equilibrium favors weaker conjugate• Distinguish strong/weak from concentrated/diluteSyllabus objective3.1.7Neutralization reactions• Acid + metal oxide/hydroxide/carbonate/hydrogencarbonate• Formulate equations and identify parent acids/bases of saltsSyllabus objective3.1.8pH curves• Strong acid-strong base titrations• Characteristic shapes• Sketch and interpret intercept and equivalence point for monoprotic titrationsSyllabus objective3.1.9(HL)—pOH scale• pOH = −log₁₀[OH⁻]• [OH⁻] = 10⁻ᵖᴼᴴ• pH + pOH = 14 (at 25°C)• Interconvert [H+], [OH-], pH, and pOHSyllabus objective3.1.10(HL)—Acid/base strength constants• Ka, Kb, pKa, pKb• Interpret relative acid/base strength from Ka, Kb, pKa, and pKbSyllabus objective3.1.11(HL)—Conjugate pair relationship• Ka × Kb = Kw• Solve problems involving Ka, Kb, and KwSyllabus objective3.1.12(HL)—Salt hydrolysis• pH depends on parent acid/base strength• Write ion hydrolysis equations and predict salt solution pHSyllabus objective3.1.13(HL)—pH curves for weak acids/bases• Four combinations: strong-strong, strong-weak, weak-strong, weak-weak• Interpret buffer region and points where pH = pKa or pOH = pKbSyllabus objective3.1.14(HL)—Acid-base indicators• Weak acids with colored conjugate pairs• Color change at pH ≈ pKa• Write indicator equilibria and include universal indicator as a mixtureSyllabus objective3.1.15(HL)—Indicator selection• End point coincides with equivalence point• Choose indicators from salt identity and indicator pH range; distinguish end point and equivalence pointSyllabus objective3.1.16(HL)—Buffer solutions• Resist pH change• Acidic buffers: weak acid + conjugate base• Basic buffers: weak base + conjugate acid• Explain buffer action using weak acid/base conjugate systemsSyllabus objective3.1.17(HL)—Buffer pH and composition• Buffer pH depends on pKa/pKb and acid/base to conjugate ratio• Solve buffer composition and pH problems using equilibrium constants• Explain the effect of dilution on buffer pHSyllabus objective