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Chapter 16 Acids and Bases

Chapter 16 Acids and Bases. Ionization of Water The pH Scale 7-4. Measuring pH. Why measure pH? Everything from swimming pools, soil conditions for plants, medical diagnosis, soaps and shampoos, etc. Sometimes we can use indicators, other times we might need a pH meter.

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Chapter 16 Acids and Bases

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  1. Chapter 16Acids and Bases Ionization of Water The pH Scale 7-4

  2. Measuring pH • Why measure pH? • Everything from swimming pools, soil conditions for plants, medical diagnosis, soaps and shampoos, etc. • Sometimes we can use indicators, other times we might need a pH meter

  3. 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

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

  5. Calculating pH, pOH pH = -log10 [H3O+] pOH = -log10 [OH-] Relationship between pH and pOH pH + pOH = 14 Finding [H3O+], [OH-] from pH, pOH [H3O+] = 10-pH [OH-] = 10-pOH

  6. In pure water, [H3O+] = [OH-] = 1  10 –7 Kw = 1  10 –14 pH + pOH = 14 pH pOH pH = -log[H+] pOH = -log[OH-] [H+] [OH-] [H+][OH-] = 1.0  10-14

  7. pH + pOH = 14

  8. 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 (-)

  9. 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-

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

  11. 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-]

  12. 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+]

  13. 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

  14. Learning Check pH The [H3O+] of lemon juice is 3.0 x 10-3 M. What is the [OH-] of the solution? Kw = [H3O+ ] [OH- ] = 1.0 x 10-14 [OH- ] = 1.0 x 10-14 [H3O+] [OH- ] = 1.0 x 10-14 = 3.3 x 10-12 M 3.0 x 10- 3

  15. pH The [H3O+] of lemon juice is 9.0 x 10- 4 M. What is the [OH-]? [OH- ] = 1.0 x 10 -14 = 1.1 x 10-11 M 9.0 x 10 - 4

  16. The [H3O+] is 4.0 x 10- 5 M. What is the [OH-]? 1.0 x 10 -14 4.0 x 10-5 Enter 1.0 EE +/- 14  4.0 EE +/- 5 = 2.5 x 10 -10

  17. Solution pH B.The [H3O+] when [OH- ] of 5 x 10-9 M Kw = [H3O+ ][OH-] = 1.0 x 10 14 [H3O+] = 1.0 x 10 -14 = 2 x 10 - 6 5 x 10- 9

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

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

  20. 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

  21. pH A. The [H3O+] of tomato juice is 1 x 10-4 M. What is the pH of the solution? answer: 4 pH = - log [ 1 x 10-4] = -(- 4) = 4

  22. pH B. The [OH-] of an ammonia solution is 1 x 10-3 M. What is the pH of the solution? Answer: 11 [H3O+] = 1 x 10-11 pH = - log [ 1 x 10- 11] = -(- 11) = 11

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

  24. Solution pH 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

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

  26. Learning Check pH A soap solution has a [H3O+] = 2 x 10-8 M. What is the pH of the solution?

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

  28. Learning Check 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 1 2 1 3 1 2

  29. What is the [H3O+ ] or [OH- ] in each of the following solutions, also state if the solution is neutral, acidic, or basic. a. 1  10 -5 M OH- b. 1  10 -7 M OH- c. 10.0 M H+ • 1.0 x 10-9 M • 1.0 x 10-7 M • 1.0 x 10-15 M

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