Concept #1: In these series of titrations the weak base is the starting solution or analyte and the strong acid is the titrant.
Concept #2: Before the equivalence point has been reached we have the formation of a buffer and utilize the Henderson Hasselbalch Equation.
Concept #3: At the equivalence point we have no remaining weak base or strong acid, but instead an excess of conjugate acid or weak acid.
Concept #4: Beyond the equivalence point we will have an excess of strong acid and conjugate acid or weak acid remaining.
Example #1: Consider the titration of 50.0 mL of 0.150 M CH3NH2 (Kb = 4.4 X 10-4) with 75.0 mL of 0.200 M HCl. Calculate the pH.
Example #2: Calculate the pH of the solution resulting from the mixing of 75.0 mL of 0.100 M NaC2H3O2 and 75.0 mL of 0.150 M HC2H3O2 with 0.0040 moles of HClO4. The Ka value of acetic acid is 1.8 x 10-5.