Weak Acid-Strong Base Titrations

Concept #1: Whenever starting these titrations it is best to determine the equivalence volume of the titrant. 

Concept #2: Before the equivalence point has been reached we have the formation of a buffer. 

Concept #3: At the equivalence point we have no remaining weak acid or strong base, but instead an excess of conjugate base. 

Concept #4: Beyond the equivalence point we will have an excess of strong base and conjugate base remaining. 

Weak Acid-Strong Base Titrations CalculationsĀ 

Example #1: A 250.0 mL solution of 0.100 M HClO is titrated with 0.200 M NaOH. What is the expected pH of the resulting solution once 50.0 mL of the NaOH solution has been added to the HClO solution?

a) 4.68

b) 7.36

c) 7.71

d) 8.20

e) 13.30

Example #2: A buffer contains 155.3 mL of 0.480 M nitrous acid, HNO2, with 100.0 mL of 0.550 M lithium nitrite, LiNO2. Find the pH after the addition of 125.0 mL of 0.400 M LiOH. The Ka of HNO2 is 4.6 x 10-4.