CHM 320 Lecture 19 Chap 12Chapter 12 - Acid-Base TitrationsHomework: Due Friday, March 17Problems 12-3, 12-6, 12-8, 12-12, 12-15, 12-19, 12-23, 12-37, 12-40, 12-42, 12-48, 12-54, 12-56CHM 320 Lecture 19 Chap 12Titration of Acids & Bases• Allows for the determination of the quantities of the acidic and basic components present in a mixture.• Allows for the determination of the Ka’s• Provides some information about buffer capacities. • Use the equations from Chapters 10 and 11 to construct titration curves.CHM 320 Lecture 19 Chap 12024681012140 5 10 15 20 25 30 35volume NaOH (mL)pHTitration Curve (weak acid titrated by strong base)1234Regions of the Titration Curve a Monoprotic AcidRegion 1: Initial point (no base added)Region 2: Before equivalence point (buffer region)Region 3: Equivalence pointRegion 4: After equivalence point (excess base)CHM 320 Lecture 19 Chap 12Determining pH of Different Regions of the Titration Curve a Monoprotic Weak AcidThe first step is to determine the volume of base needed to reach the equivalence point. Use the concentration and volume of acid.Region 1: Initial point (no base added) – The pH is determined from the concentration of the weak acid. x2/(F-x) = Kax = [H+]Region 2: Before equivalence point (buffer region) – The pH is determined using the Henderson-Hasselbalch equation (buffer)pH = pKa + log([base]/[acid])Region 3: Equivalence point – The pH is determined from the concentration of the weak acid (now converted to its conjugate base) and the dilution factor.Region 4: After equivalence point (excess base) – The pH is determined from the concentration of excess [OH-] present.CHM 320 Lecture 19 Chap 12Calculate the pH at each point for the titration of 100.0 mL of 0.100 M cocaine (Kb= 2.6x10-6) with 0.200 M HNO3. Va= 0.0, 10.0, 20.0, 25.0, 30.0, 40.0, 49.9, 50.0, 50.1, 51.0, and 60.0 mL. Draw a graph of pH versus