Chapter 9 Acids and Bases

1
Chapter 9Acids and Bases

• Ionization of Water
• The pH Scale

2
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 (-)

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 M 1 x 10-7 M

H3O
OH-
4
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-

H3O
OH-
6
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

OH-
H3O
7
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

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

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

10
Using the Calculator

• 1.0 x 10 -14
• 4.0 x 10-5
• Enter 1.0 EE /- 14 ?? 4.0 EE /- 5
  
• 2.5 x 10 -10