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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Chapter 18: TWO CLASSES OF CHEMICAL REACTIONS.

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Presentation on theme: "Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Chapter 18: TWO CLASSES OF CHEMICAL REACTIONS."— Presentation transcript:

1 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Chapter 18: TWO CLASSES OF CHEMICAL REACTIONS

2 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley This lecture will help you understand: Acids Donate Protons, Bases Accept Them Relative Strengths of Acids and Bases Acidic, Basic, and Neutral Solutions Acidic Rain and Basic Oceans Losing and Gaining Electrons Harnessing the Energy of Flowing Electrons Electrolysis Corrosion and Combustion

3 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acids Donate Protons, Bases Accept Them

4 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acids Donate Protons, Bases Accept Them

5 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid A chemical that donates a hydrogen ion, H + Base A chemical that accepts a hydrogen ion, H + Acids Donate Protons, Bases Accept Them

6 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

7 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

8 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

9 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

10 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

11 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

12 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

13 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

14 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

15 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

16 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

17 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

18 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

19 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

20 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

21 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion proton

22 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley BaseBase AcceptsAccepts AcidAcid DonatesDonates

23 H2OH2OHCl +

24 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2OHCl +

25 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – +

26 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++

27 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++

28 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++ donordonor acceptoracceptor

29 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++ (acid)(base)

30 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

31 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

32 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – +

33 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

34 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – +

35 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

36 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

37 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ donordonor acceptoracceptor

38 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ (acid)(base)

39 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

40 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

41 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 + (acid)(base) +

42 Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ (acid)(base)(acid)(base)

43 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as an acid, what does it lose? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

44 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as an acid, what does it lose? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

45 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as a base, what does it gain? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

46 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as a base, what does it gain? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

47 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H + H O H H O H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

48 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H + H O H H O H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

49 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H O H Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

50 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H O H Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

51 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

52 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

53 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

54 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. + H O H H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

55 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

56 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

57 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

58 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What salt forms from the reaction of hydrogen chloride, HCl, with potassium hydroxide, KOH? A.KCl B.H 3 OCl C.KOH 2 D.KOH 2 Cl Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

59 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What salt forms from the reaction of hydrogen chloride, HCl, with potassium hydroxide, KOH? A.KCl B.H 3 OCl C.KOH 2 D.KOH 2 Cl Explanation: The K + from the KOH combines with the Cl – from the HCl. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

60 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases Strong acids and bases ionize completely in water.

61 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases Strong acids and bases ionize completely in water.

62 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Weak acids and bases do not ionize completely in water. Relative Strengths of Acids and Bases

63 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Weak acids and bases do not ionize completely in water. Relative Strengths of Acids and Bases

64 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases

65 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions Water can behave as an acid or a base.

66 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. Acidic, Basic, and Neutral Solutions

67 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. So in pure water, [H 3 O + ] = [OH – ] = 0.0000001 M = 10 –7 M. Acidic, Basic, and Neutral Solutions

68 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. So, in pure water, [H 3 O + ] = [OH – ] = 0.0000001 M = 10 –7 M. Acidic, Basic, and Neutral Solutions

69 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. Add hydronium ions, H 3 O +, and the solution is “acidic,” Add hydroxide ions, OH –, and the solution is “basic.” Acidic, Basic, and Neutral Solutions

70 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions

71 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley As sodium hydroxide, NaOH, is added to water, the hydroxide ion, OH –, concentration A.increases. B.decreases. C.remains the same. Acidic, Basic, and Neutral Solutions CHECK YOUR NEIGHBOR

72 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley As sodium hydroxide, NaOH, is added to water, the hydroxide ion, OH –, concentration A.increases. B.decreases. C.remains the same. Explanation: The bond between sodium and oxygen is ionic. When dissolved in water, it separates into sodium ions and hydroxide ions, much like sodium chloride, NaCl, separates into sodium and chloride ions. Acidic, Basic, and Neutral Solutions CHECK YOUR ANSWER

73 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. Acidic, Basic, and Neutral Solutions

74 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] Acidic, Basic, and Neutral Solutions

75 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] For pure water: pH = –log (10 –7 ) pH = –(– 7) pH = 7 Acidic, Basic, and Neutral Solutions

76 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] For pure water: pH = –log (10 –7 ) pH = –(–7) pH = 7 What is a log? Acidic, Basic, and Neutral Solutions

77 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Acidic, Basic, and Neutral Solutions

78 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Quiz Time What is the log of 10 2 ? Acidic, Basic, and Neutral Solutions

79 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Quiz Time What is the log of 10 2 ? Log 10 2 = 2 (the power to which 10 is raised) Acidic, Basic, and Neutral Solutions

80 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 Acidic, Basic, and Neutral Solutions

81 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 Acidic, Basic, and Neutral Solutions

82 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 Acidic, Basic, and Neutral Solutions

83 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 –1 = 0.1 Acidic, Basic, and Neutral Solutions

84 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 –1 = 0.1 10 –2 = 0.01 Acidic, Basic, and Neutral Solutions

85 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Acidic, Basic, and Neutral Solutions

86 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = ? 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Three zeros Acidic, Basic, and Neutral Solutions

87 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = ? 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Two zeros Acidic, Basic, and Neutral Solutions

88 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = ? 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 One zero Acidic, Basic, and Neutral Solutions

89 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Zero zeros! Acidic, Basic, and Neutral Solutions

90 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1000 = ? Acidic, Basic, and Neutral Solutions

91 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1000 = ? Log 10 3 = Acidic, Basic, and Neutral Solutions

92 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1000 = ? Log 10 3 = 3 Acidic, Basic, and Neutral Solutions

93 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1 = ? Acidic, Basic, and Neutral Solutions

94 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1 = ? Log 10 0 = Acidic, Basic, and Neutral Solutions

95 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 1 = ? Log 10 0 = 0 Acidic, Basic, and Neutral Solutions

96 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 10 – 7 = Acidic, Basic, and Neutral Solutions

97 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. 10 3 = 1000 10 2 = 100 10 1 = 10 10 0 = 1 10 –1 = 0.1 10 –2 = 0.01 10 –3 = 0.001 Quiz Time Log 10 – 7 = – 7 Acidic, Basic, and Neutral Solutions

98 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH = –log [H 3 O + ] For acidic water pH < 7, for example: pH = –log (10 –5 ) pH = –(–5) pH = 5 Acidic, Basic, and Neutral Solutions

99 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH = –log [H 3 O + ] For basic water pH > 7, for example: pH = –log (10 –9 ) pH = –(–9) pH = 9 Acidic, Basic, and Neutral Solutions

100 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions

101 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans Acid rain has a pH lower than 5. 2 SO 2 (g) + O 2 (g)  SO 3 (g) SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq)

102 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans Acid rain has a pH lower than 5. SO 2 released from burning coal and oil. 2 SO 2 (g) + O 2 (g)  SO 3 (g) SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq)

103 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans CO 2 levels in atmosphere rising CO 2 (g) + H 2 O (l)  H 2 CO 3 (aq)

104 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

105 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

106 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

107 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons Acid–Base reactions: transfer of proton

108 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid–Base reactions: transfer of proton Oxidation-Reduction reactions: transfer of ??? Losing and Gaining Electrons

109 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid–Base reactions: transfer of proton Oxidation-Reduction reactions: transfer of electron Losing and Gaining Electrons

110 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron Losing and Gaining Electrons

111 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na + + 2 e – Losing and Gaining Electrons

112 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na + + 2 e – Reduction: The gain of an electron Losing and Gaining Electrons

113 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na + + 2 e – Reduction: The gain of an electron Cl 2 + 2 e – 2 Cl – Losing and Gaining Electrons

114 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na + + 2 e – Reduction: The gain of an electron Cl 2 + 2 e – 2 Cl – “Leo” “Ger” Losing and Gaining Electrons

115 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na + + 2 e – Reduction: The gain of an electron Cl 2 + 2 e – 2 Cl – “Leo” “Ger” (Leo the lion went “Ger”) Losing and Gaining Electrons

116 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley 2 Na + Cl 2 2 Na + + 2 Cl – Losing and Gaining Electrons

117 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons

118 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons

119 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What element within the reactants is oxidized in the following equation, and what element is reduced? I 2 + 2 Br –  2 I – + Br 2 A.Iodine, I, is oxidized, while the bromine ion, Br –, is reduced. B.Iodine, I, is reduced, while the bromine ion, Br –, is oxidized. C.Both the iodine, I, and the bromine ion, Br –, are reduced. D.Both the iodine, I, and the bromine ion, Br –, are oxidized. Losing and Gaining Electrons CHECK YOUR NEIGHBOR

120 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley I 2 + 2 Br –  2 I – + Br 2 A.Iodine, I, is oxidized, while the bromine ion, Br –, is reduced. B.Iodine, I, is reduced, while the bromine ion, Br –, is oxidized. C.Both the iodine, I, and the bromine ion, Br –, are reduced. D.Both the iodine, I, and the bromine ion, Br –, are oxidized. Explanation: Note how the iodine gains a negative charge, while the bromine loses the negative charge. What element within the reactants is oxidized in the following equation and what element is reduced? Losing and Gaining Electrons CHECK YOUR ANSWER

121 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Electric currents generated by oxidation- reduction reactions.

122 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Electric currents generated by oxidation- reduction reactions. Useful for: –Batteries –Fuel cells

123 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Ions must be able to flow to generate a current.

124 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons A salt bridge allows this to happen.

125 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons A battery is a self-contained voltaic cell.

126 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The positive electrode is the cathode, where reduction occurs. Harnessing the Energy of Flowing Electrons

127 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The positive electrode is the cathode, where reduction occurs. The negative electrode is the anode, where the oxidation occurs. Harnessing the Energy of Flowing Electrons

128 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Several types of batteries: –Dry cell –Alkaline –Rechargeable NiMH Lithium

129 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Fuel cells convert the chemical energy of a fuel into electrical energy. Harnessing the Energy of Flowing Electrons

130 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons

131 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis Electrolysis uses electrical energy to produce chemical change.

132 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis Electrolysis uses electrical energy to produce chemical change. Examples: –Recharging your car battery –Purifying metal ores

133 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis

134 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion

135 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Corrosion The process whereby a metal deteriorates through oxidation-reduction reactions.

136 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Corrosion The process whereby a metal deteriorates through oxidation-reduction reactions. It can be prevented by coating the metal with zinc, which oxidizes first.

137 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Combustion An oxidation-reduction reaction between a nonmetallic material, such as wood, and oxygen.

138 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley One of the products of combustion is water. Why doesn’t this water extinguish the combustion? A.While areas of combustion are being extinguished, new areas are combusting. B.Combustion only produces microscopic amounts of water. C.The chemical combustion reaction is happening too fast for the water to have an effect on the fire. D.This water is in the gaseous phase and merely floats away. Corrosion and Combustion CHECK YOUR NEIGHBOR

139 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley One of the products of combustion is water. Why doesn’t this water extinguish the combustion? A.While areas of combustion are being extinguished, new areas are combusting. B.Combustion only produces microscopic amounts of water. C.The chemical combustion reaction is happening too fast for the water to have an effect on the fire. D.This water is in the gaseous phase and merely floats away. Explanation: Carefully place your hand over a campfire, and you can feel the greater humidity as water vapor escapes. Corrosion and Combustion CHECK YOUR ANSWER


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