Chapter 16 Acids and Bases

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Chapter 16Acids and Bases

• Ionization of Water
• The pH Scale
• 7-4

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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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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

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pH of Some Common Bases

• blood 7.4
• tears 7.4
• seawater 8.4
• milk of magnesia 10.6
• household ammonia 11.0

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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
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In pure water, H3O OH- 1 ? 10 7 Kw
1 ? 10 14
pH pOH 14
pH
pOH
pOH -logOH-
pH -logH
H
OH-
HOH- 1.0 ? 10-14
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pH pOH 14
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Ionization of Water

• Occasionally, in water, a H is transferred
  between H2O molecules
• . . . . . .
  . .
• HO OH HOH OH-
• . . . . . .
  . .
• H H H
• water molecules hydronium hydroxide
  ion ()
  ion (-)

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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 M 1 x 10-7 M

H3O
OH-
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Ion Product of Water Kw

• Molar concentration
• Kw H3O OH-
• 1 x 10-7 1 x 10-7
• 1 x 10-14

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Acids

• Increase H
• HCl (g) H2O (l) H3O (aq) Cl- (aq)
• More H3O than water gt 1 x 10-7M
• As H3O increases, OH- decreases
• H3O gt OH-

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Bases

• Increase the hydroxide ions (OH-)
• H2O
• NaOH (s) Na(aq) OH- (aq)
• More OH- than water, OH- gt 1 x 10-7M
• When OH- increases, H3O decreases
• OH? gt H3O

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Using Kw

• The OH- of a solution is 1.0 x 10- 3 M. 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

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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

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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

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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

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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

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pH

• Indicates the acidity H3O of the solution
• pH - log H3O
• From the French pouvoir hydrogene
• (hydrogen power or power of
• hydrogen)

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pH

• In the expression for H3O
• 1 x 10-exponent
• the exponent pH
• H3O 1 x 10-pH M

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pH Range

• 0 1 2 3 4 5 6 7 8 9 10 11 12
  13 14
• Neutral
• HgtOH- H OH-
  OH-gtH

Acidic
Basic
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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

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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

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Some H3O and pH

• H3O pH
• 1 x 10-5 M 5
• 1 x 10-9 M 9
• 1 x 10-11 M 11

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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

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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

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Learning Check pH

• A soap solution has a H3O 2 x 10-8 M. What
  is the pH of the solution?

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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

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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

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2
1
3
1
2
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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. 1.0 x 10-9 M
2. 1.0 x 10-7 M
3. 1.0 x 10-15 M

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