1. Write chemical reactions that describe:
a weak acid
a weak acid titrated with a strong base before the equivalence point
a weak acid titrated with a strong base at the equivalence point.
What are the relative quantities of the substances in solution at each point?

2. Titrations MATH!!!! [H+] Ka Kb weak base indicator strong acid
equivalence point

3. To Find the Equivalence Point
(ex) When titrating 50.0mL of 0.48M HCN with 0.75M NaOH, what volume of base must be added to reach the equivalence point?

4. Strong Acid with Strong Base

5. Strong Acid with Strong Base
Before the equivalence point, pH is determined by the amount of unneutralized strong acid.
At the equivalence point, the pH is 7.
After the equivalence point, pH is determined by the amount of excess strong base added.

6. 25.0 mL of 0.20M HCl titrated with 0.20M NaOH
First, where is the equivalence point?
initial pH:
pH after 15mL of NaOH added:
pH at equiv pt:
pH after 40.0 mL of NaOH added:

7. 25.0 mL of 0.20M HCl titrated with 0.20M NaOH
initially:
after 15mL of NaOH added:

8. 25.0 mL of 0.20M HCl titrated with 0.20M NaOH
at equiv pt:
after 40.0 mL of NaOH added:

9. See summary: middle of p.772 in textbook

10. Notice the differences between a strong acid titration shown in red and a weak acid titration shown in blue (both titrated with a strong base).

11. Visual differences between SA-SB and WA-SB titration curves:
Initial pH higher when starting with weak acid
The pH of a weak acid rises faster at the start
and slower at the equivalence point.
Recognize that a buffer solution forms during this portion.
3. pH at the equivalence point >7 with a weak acid

12. Titrating a Weak Acid
Initially, you have a weak acid. Calculate pH with an ICE table and the Ka value
Before the equivalence point, added strong base creates some conjugate base of original weak acid. Use rxn stoichiometry to calc amounts of weak acid and conjugate base present; use in Henderson-Hasselback equation to calculate pH.

13. Titrating a Weak Acid
At the equivalence point, all weak acid has been neutralized and only conjugate base remains in solution. pH is determined using base hydrolysis reaction and Kb.
After the equivalence point, pH is determined by the amount of excess strong base added. (Same as strong acid-strong base titration)

14. 50.0mL of 0.25M HC2H3O2 titrated with 0.20M NaOH
First, where is the equivalence point?

15. 50.0mL of 0.25M HC2H3O2 titrated with 0.20M NaOH
initially:
after 15mL of NaOH added:

16. 50.0mL of 0.25M HC2H3O2 titrated with 0.20M NaOH
at equiv pt:

17. 50.0mL of 0.25M HC2H3O2 titrated with 0.20M NaOH
after 85.0mL of NaOH added: