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

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

3. Pure Water is Neutral H2O + H2O H3O+ + OH- H3O+ OH-
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 ][ 1 x 10-7 ]
= x 10-14

5. Acids H3O+ OH- 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-

6. Bases OH- H3O+ 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+

7. Using Kw
The [OH- ] of a solution is 1.0 x M. What is the [H3O+]?
Kw = [H3O+ ] [OH- ] = x 10-14
[H3O+] = 1.0 x 10-14
[OH-]
[H3O+] = x = 1.0 x 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 M
3) 1.0 x 1011 M

9. Solution pH1
The [H3O+] of lemon juice is 1.0 x M. What is the [OH-]?
[OH- ] = x = 1.0 x M
1.0 x

10. Using the Calculator 1.0 x 10 -14 4.0 x 10-5
Enter 1.0 EE +/  EE +/- 5
= 2.5 x