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It is Wednesday. The first homework is due. Place it on the bench in front.

It is Wednesday. The first homework is due. Place it on the bench in front. Acids and bases of varying strengths. Acids and bases of varying strengths. Strong acid = 100% ionization. Strong acid = 100% donation of acidic proton.

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It is Wednesday. The first homework is due. Place it on the bench in front.

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  1. It is Wednesday. The first homework is due. Place it on the bench in front.

  2. Acids and bases of varying strengths.

  3. Acids and bases of varying strengths. Strong acid = 100% ionization Strong acid = 100% donation of acidic proton.

  4. HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)

  5. HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq) [H3O+][Cl-] K = [HCl]

  6. HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq) [H3O+][Cl-] large K = = [HCl]

  7. Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq)

  8. Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = acidity constant = Ka [HA]

  9. Generic acid HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = acidity constant = Ka [HA] -log10 Ka = pKa

  10. Acid Ka pKa HI  1011-11 HCl  107  -7 H2SO4  102  -2 CH3COOH 1.8 x 10-5 4.74 Table page 332

  11. Base strength

  12. Base strength Inversely related to strength of conjugate acid.

  13. Base strength Inversely related to strength of conjugate acid. H2O(l) + B(aq) HB+(aq) + OH-(aq) conjugate acid

  14. H2O(l) + B(aq) HB+(aq) + OH-(aq) [HB+][OH-] = Kb = basicity constant [B]

  15. [HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] [H3O+][OH-] = Kw

  16. [HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] Conjugate acid [H3O+][OH-] = Kw KbKa = Kw

  17. [HB+][OH-] = Kb = basicity constant [B] [H3O+][B] = acidity constant = Ka [HB+] [H3O+][OH-] = Kw KbKa = Kw pKb + pKa = pKw

  18. KbKa = Kw pKb + pKa = pKw Expressions can be used for any conjugate acid-base pair in water.

  19. Indicators : Usually a weak organic acid that has a color different from its conjugate base.

  20. Indicators : Usually a weak organic acid that has a color different from its conjugate base. HA + H2O H3O+ + A-

  21. phenolphthalein

  22. Indicators : Usually a weak organic acid that has a color different from its conjugate base. + H2O H3O+ + A-

  23. phenolphthalein

  24. Equilibria with weak acids and weak bases.

  25. Equilibria with weak acids and weak bases. Weak acid:

  26. Equilibria with weak acids and weak bases. Weak acid: Ka < 1

  27. Equilibria with weak acids and weak bases. Weak acid: Ka < 1 [H3O+][A-] Ka = [HA]

  28. Equilibria with weak acids and weak bases. Weak acid: Ka < 1 Ka (H3O+) = 1

  29. Equilibria with weak acids and weak bases. Weak acid: Ka < 1 Ka (H3O+) = 1 Why is a weak acid weak?

  30. HCl Ka 107 strong HF Ka = 6.6 x 10-4 weak

  31. HCl Ka 107 strong HF Ka = 6.6 x 10-4 weak HF more ionic than HCl

  32. HCl Ka 107 strong HF Ka = 6.6 x 10-4 weak HF more ionic than HCl Relative Kas show that HF holds proton more strongly than HCl

  33. HCl Ka 107 strong HF Ka = 6.6 x 10-4 weak HF more ionic than HCl Relative Kas show that HF holds proton more strongly than HCl Electrostatic attraction for H+ stronger for F- than for Cl-.

  34. Organic acids Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  35. Organic acids Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  36. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1 The more stable the conjugate base, the stronger the acid.

  37. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  38. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  39. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  40. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  41. Ka CH3COOH 1.8 x 10-5 CH3CH2COOH 1.3 x 10-5 CCl3COOH 2 x 10-1

  42. Equilibria with weak acids and weak bases. HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = Ka [HA]

  43. HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = Ka [HA]

  44. HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = Ka [HA] CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq)

  45. HA(aq) + H2O(l) H3O+(aq) + A-(aq) [H3O+][A-] = Ka [HA] CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5

  46. CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5 1 mol CH3COOH 1 L water solution

  47. CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO-(aq) Ka = 1.8 x 10-5 1 mol CH3COOH Calculate pH 1 L water solution

  48. [CH3COOH] [H3O+] [CH3COO-] [M] 1.0 0 0 initial change Eq.

  49. [CH3COOH] [H3O+] [CH3COO-] [M] 1.0 0 0 initial change -y +y +y Eq.

  50. [CH3COOH] [H3O+] [CH3COO-] [M] 1.0 0 0 initial change -y +y +y Eq. 1.0 -y y y

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