1. Drill: A 0.100 M solution of HZ ionizes 20.0 %. Calculate: K aHZ

2. Distribute Make-Up Titration Labs

3. Return & Review Tests

4. CHM II HW Review PP-23 Complete the attached assignment & turn it in on Monday

5. Buffer Solutions

6. Buffer Solution A solution that resists changes in pH

7. Buffer Solution Made from the combination of a weak acid & its salt

8. Buffer Solution Made from the combination of a weak base & its salt

9. Buffer Examples Mix acetic acid & sodium acetate Mix ammonia & ammonium chloride

10. Buffer Solution A buffer solution works best when the acid to salt ratio is 1 : 1

11. Buffer Solution A buffer solution works best when the base to salt ratio is 1 : 1

12. Buffer Solution The buffering capacity of a solution works best when the pH is near the pK a

13. pK a or pK b pK a = - log K a pK b = - log K b

14. Buffer Equilibria

15. Buffer Problems Calculate the pH of a solution containing 0.10 M HAc in 0.10 M NaAc: K a = 1.8 x 10 -5

16. AP CHM HW Problem: 9 Page: 421

17. CHM II HW Problem: 11 Page: 818

18. Buffer Problems Calculate the pH of 0.10 M NH 3 in 0.20 M NH 4 NO 3 : K b = 1.8 x 10 -5

19. Buffer Problems Calculate the pH of a solution containing 0.10 M HBz in 0.20 M NaBz: K a = 6.4 x 10 -5

20. Drill: Calculate the pH of a solution containing 0.30 M HZ in 0.10 M NaZ: K a = 3.0 x 10 -5

21. Review Drill & Check HW

22. All who were absent for the Titration Lab need to get a make-up lab.

23. The Titration Lab is due Wednesday

24. Anyone who wants to retake the last test should see me to make arrangements to make it up.

25. Anyone who has missed a previous test should also see me to make arrangements to make it up.

26. CHM II HW Review PP-23 Complete the attached assignment & turn it in tomorrow.

27. Buffer Problem Calculate the pH of a solution containing 0.50 M R-NH 2 in 0.10 M R-NH 3 I: K b = 4.0 x 10 -5

28. HAH + + A - [ H + ][ A - ] [ HA ] K a =

29. HAH + + A - [ K a ][ HA ] [ A - ] [H + ]=

30. HAH + + A - [ HA ] [ A - ] [H + ] = (K a )

31. pH = [ HA ] [ A - ] pK a - log

32. Henderson- Hasselbach Eq [A - ] [HA] pH = pK a + log

33. Henderson- Hasselbach Eq [B + ] [B] pOH = pK b + log

34. Buffer Problems Calculate the salt to acid ratio to make a buffer solution with pH = 5.0 K a for HBZ = 2.0 x 10 -5

35. Equivalence Point Point at which the # of moles of the two titrants are equal

36. Titration Curves

38. AP CHM HW Read: Chapter 14 Problem: 23 Page: 421

39. CHM II HW Read: Chapter 19 Problem: 21 Page: 819

40. Buffer Problems Calculate the salt to base ratio to make a buffer solution with pH = 9.48 K b for MOH = 2.0 x 10 -5

41. Drill: Calculate the pH of a buffer solution containing 0.50 M HX in 0.25 M KX. Ka = 2.5 x 10 -5

42. Test Friday

44. Calculate the HCO 3 - to H 2 CO 3 ratio in blood with pH = 7.40 K a1 for H2CO3 = 4.4 x 10 -7

45. 150 ml of 0.10 M NaOH is added to 100.0 ml of 0.10 M H 2 CO 3. Calculate pH. K a1 for H2CO3 = 4.4 x 10 -7 K a2 for H2CO3 = 4.8 x 10 -11

46. AP CHM HW Read: Chapter 14 Problem: 33 Page: 422

47. CHM II HW Read: Chapter 19 Problem: 31 Page: 819