1. Titration Curves Chemistry 3202

2. Titration Curves A titration curve is a graph of changes in pH during a titration. The shape of the curve depends on the strengths of the acids and bases used in the titration. The endpoint occurs at the middle of the steep section of the curve

3. Endpoint pH = 7 Strong Acid with Strong Base acid is in the flask base is in the buret

4. Strong Base with Strong Acid pH = 7 Endpoint

5. pH < 7 Weak Base with Strong Acid Endpoint

6. Weak Acid with Strong Base pH > 7 Endpoint

7. SA with SB

8. WB with SA

9. SB with SA

10. WA with SB

11. WA with WB

12. 1 st Endpoint 2 nd Endpoint Diprotic acid with SB

14. Indicators An indicator is a weak acid that changes color with changes in pH To choose an indicator for a titration, the pH of the endpoint must be within the pH range over which the indicator changes color

15. pH = 5.3 litmus methyl red chlorophenol red What color change for each indicator? → blue to red → red to yellow → yellow to red

16. Buffers A solution of a WA and its conjugate base, or a WB and its conjugate acid is called a buffer solution. eg. a solution with both CH 3 COOH (aq) and CH 3 COO - (aq)

17. Buffers The pH of a buffer solution changes slightly when moderate amounts acid or base are added. The buffer capacity is the amount of acid or base that can be added before considerable change in pH.

18. Buffers Write the equation to show what happens when: a) acid (H 3 O + ) & b) base (OH - ) is added to a CH 3 COOH (aq) /CH 3 COO - (aq) buffer.