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Chapter 9 Acids and Bases

Chapter 9 Acids and Bases. Ionization of Water The pH Scale. Ionization of Water. Occasionally, in water, a H + is transferred between H 2 O molecules . . . . . . . . H : O : + : O : H H : O : H + + : O : H -

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Chapter 9 Acids and Bases

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  1. Chapter 9Acids and Bases Ionization of Water The pH Scale LecturePLUS Timberlake

  2. Ionization of Water Occasionally, in water, a H+ is transferred between H2O molecules . . . . . . . . H:O: + :O:H H:O:H + + :O:H- . . . . . . . . HH H water molecules hydronium hydroxide ion (+)ion (-) LecturePLUS Timberlake

  3. Pure Water is Neutral Pure water contains small, but equal amounts of ions: H3O+ and OH- H2O + H2O H3O+ + OH- hydronium hydroxide ion ion 1 x 10-7 M1 x 10-7 M H3O+ OH- LecturePLUS Timberlake

  4. Ion Product of Water Kw [ ] = Molar concentration Kw = [ H3O+ ] [ OH- ] = [ 1 x 10-7 ][ 1 x 10-7 ] = 1 x 10-14 LecturePLUS Timberlake

  5. Acids • Increase H+ • HCl (g) + H2O (l)H3O+(aq) + Cl-(aq) • More [H3O+] than water > 1 x 10-7M • As H3O+ increases, OH- decreases [H3O+] > [OH-] H3O+ OH- LecturePLUS Timberlake

  6. Bases • Increase the hydroxide ions (OH-) H2O • NaOH (s) Na+(aq) + OH- (aq) • More [OH-] than water, [OH-] > 1 x 10-7M • When OH- increases, H3O+ decreases [OH] > [H3O+] OH- H3O+ LecturePLUS Timberlake

  7. Using Kw The [OH- ] of a solution is 1.0 x 10- 3M. What is the [H3O+]? Kw = [H3O+ ] [OH- ] = 1.0 x 10-14 [H3O+] = 1.0 x 10-14 [OH-] [H3O+] = 1.0 x 10-14= 1.0 x 10-11 M 1.0 x 10- 3 LecturePLUS Timberlake

  8. Learning Check pH1 The [H3O+] of lemon juice is 1.0 x 10-3 M. What is the [OH-] of the solution? 1) 1.0 x 103 M 2) 1.0 x 10-11 M 3) 1.0 x 1011 M LecturePLUS Timberlake

  9. Solution pH1 The [H3O+] of lemon juice is 1.0 x 10- 3 M. What is the [OH-]? [OH- ] =1.0 x 10 -14 = 1.0 x 10-11 M 1.0 x 10 - 3 LecturePLUS Timberlake

  10. Using the Calculator 1.0 x 10 -14 4.0 x 10-5 Enter1.0 EE +/- 14 4.0 EE+/- 5 = 2.5 x 10 -10 LecturePLUS Timberlake

  11. Learning Check pH2 The [OH-] of a solution is 5 x 10 -5 M. What is the [H3O+ ] of the solution? 1) 2 x 10- 5 M 2) 1 x 1010 M 3) 2 x 10-10 M LecturePLUS Timberlake

  12. Solution pH2 The [OH-] of a water solution is 5 x 10-5 M. What is the [H3O+] in the solution? [ H3O+] =1.0 x 10 -14 5 x 10- 5 On some calculators: 1.0 EE +/- 14 5 EE +/-5 = 2 x 10 -10 M LecturePLUS Timberlake

  13. Learning Check pH3 A.The [OH-] when [H3O+ ] of 1 x 10- 4 M 1) 1 x 10-6 M 2) 1 x 10-8 M 3) 1 x 10-10 M B.The [H3O+] when [OH- ] of 5 x 10-9 M 1) 1 x 10- 6 M 2) 2 x 10- 6 M 3) 2 x 10-7 M LecturePLUS Timberlake

  14. Solution pH3 Kw = [H3O+ ][OH-] = 1.0 x 10 14 A. (3) [OH- ] = 1.0 x 10 -14 = 1.0 x 10 -10 1.0 x 10- 4 B.(2) [H3O+] = 1.0 x 10 -14 = 2 x 10 - 6 5 x 10- 9 LecturePLUS Timberlake

  15. pH • Indicates the acidity [H3O+] of the solution • pH = - log [H3O+] • From the French pouvoir hydrogene (“hydrogen power” or power of hydrogen) LecturePLUS Timberlake

  16. pH In the expression for [H3O+] 1 x 10-exponent the exponent = pH [H3O+] = 1 x 10-pH M LecturePLUS Timberlake

  17. pH Range 0 1 2 3 4 5 6 7 8 910 11 12 13 14 Neutral [H+]>[OH-][H+] = [OH-][OH-]>[H+] Acidic Basic LecturePLUS Timberlake

  18. Some [H3O+] and pH [H3O+] pH 1 x 10-5 M 5 1 x 10-9 M 9 1 x 10-11M 11 LecturePLUS Timberlake

  19. pH of Some Common Acids gastric juice 1.0 lemon juice 2.3 vinegar 2.8 orange juice 3.5 coffee 5.0 milk 6.6 LecturePLUS Timberlake

  20. pH of Some Common Bases blood 7.4 tears 7.4 seawater 8.4 milk of magnesia 10.6 household ammonia 11.0 LecturePLUS Timberlake

  21. Learning Check pH4 A. The [H3O+] of tomato juice is 1 x 10-4 M. What is the pH of the solution? 1) - 4 2) 4 3) 8 B. The [OH-] of an ammonia solution is 1 x 10-3 M. What is the pH of the solution? 1) 3 2) 11 3) -11 LecturePLUS Timberlake

  22. Solution pH4 A. pH = - log [ 1 x 10-4] = -(- 4) = 4 B. [H3O+] = 1 x 10-11 pH = - log [ 1 x 10- 11] = -(- 11) = 11 LecturePLUS Timberlake

  23. Learning Check pH5 The pH of a soap is 10. What is the [H3O+] of the soap solution? 1) 1 x 10 - 4 M 2) 1 x 1010 M 3) 1 x 10 - 10 M LecturePLUS Timberlake

  24. Solution pH5 The pH of a soap is 10. What is the [H3O+] of the soap solution? [H3O+] = 1 x 10-pH M = 1 x 10-10 M LecturePLUS Timberlake

  25. pH on the Calculator [H3O+] is 4.5 x 10-6 M pH = 4.5 x EXP(or EE) 6+/- LOG +/- = 5.35 LecturePLUS Timberlake

  26. Learning Check pH6 A soap solution has a [H3O+] = 2 x 10-8 M. What is the pH of the solution? 1) 8 2) 7.7 3) 6 LecturePLUS Timberlake

  27. Solution pH6 A soap solution has a [H3O+] = 2.0 x 10-8 M. What is the pH of the solution? B) 2.0 EE 8 +/- LOG +/- = 7.7 LecturePLUS Timberlake

  28. Learning Check pH7 Identify each solution as 1. acidic 2. basic 3. neutral A. _____ HCl with a pH = 1.5 B. _____ Pancreatic fluid [H+] = 1 x 10-8 M C. _____ Sprite soft drink pH = 3.0 D. _____ pH = 7.0 E. _____ [OH- ] = 3 x 10-10 M F. _____ [H+ ] = 5 x 10-12 LecturePLUS Timberlake

  29. Solution pH7 Identify each solution as 1. acidic 2. basic 3. neutral A. _1__ HCl with a pH = 1.5 B. _2__ Pancreatic fluid [H+] = 1 x 10-8 M C. _1__ Sprite soft drink pH = 3.0 D. _3__ pH = 7.0 E. _1__ [OH-] = 3 x 10-10 M F. _2__ [H+] = 5 x 10-12 LecturePLUS Timberlake

  30. Acid Rain • Unpolluted rain has a pH of 5.6 • Rain with a pH below 5.6 is “acid rain“ • CO2 in the air forms carbonic acid CO2 + H2O H2CO3 • Adds to H+ of rain H2CO3 H+ (aq) + HCO3-(aq) Formation of acid rain: 1. Emission of sulfur and nitrogen oxides from the burning of fuels expecially coal with high S content, power stations, oil refineries, vehicles as well as bacterial decomposition, and lighting hitting N2 SO2 26 million tons in 1980 NO and NO2 22 million tons in 1980 Mt. St Helens (1980) 400,000 tons SO2 2. Reactions in the atmosphere form SO3 2SO2 + O2 2 SO3 3. Reactions with atmosphere water form acids SO3 + H2O  H2SO4 sulfuric acid NO + H2O  HNO2 nitrous acid HNO2 + H2O  HNO3 nitric acid 4. Effects of Acid Rain Decline in fish populations in rivers and lasts due to toxic effect of Al leached from soil by acid rain Extensive fish kills in spring from runoff due to accumulation of large amounts of acid on the snow Dissolves minerals Mg, Ca, and K from the soil and waxy coatings that protect leaves from bacteria Corrodes metals, textiles, paper and leather LecturePLUS Timberlake

  31. Sources of Acid Rain • Power stations • Oil refineries • Coal with high S content • Car and truck emissions • Bacterial decomposition, and lighting hitting N2 LecturePLUS Timberlake

  32. SO2 26 million tons in 1980 NO and NO2 22 million tons in 1980 Mt. St Helens (1980) 400,000 tons SO2 • Reactions with oxygen in air form SO3 2SO2 + O2 2 SO3 • Reactions with water in air form acids SO3 + H2O H2SO4 sulfuric acid NO + H2O HNO2 nitrous acid HNO2 + H2O HNO3 nitric acid LecturePLUS Timberlake

  33. Effects of Acid Rain • Leaches Al from soil, which kills fish • Fish kills in spring from runoff due to accumulation of large amounts of acid in snow • Dissolves waxy coatings that protect leaves from bacteria • Corrodes metals, textiles, paper and leather LecturePLUS Timberlake

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