1. Ch. 19 – Acids & Bases
II. pH (p. 644 – 658)

2. Self-Ionization of Water
A. Ionization of Water
H2O + H2O H3O+ + OH-
Self-Ionization of Water

3. Kw = [H3O+][OH-] = 1.0  10-14 A. Ionization of Water
Ion Product Constant for Water
The ion production of water, Kw = [H3O+][OH–]
Pure water contains equal concentrations of H+ and OH– ions, so [H3O+] = [OH–]
For all aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals 1.0 x 10-14

4. A. Ionization of Water
Find the hydroxide ion concentration of 3.0  10-2 M HCl.
HCl → H Cl-
3.0  10-2M  10-2M
[H3O+][OH-] = 1.0  10-14
[3.0  10-2][OH-] = 1.0  10-14
[OH-] = 3.3  M

5. A. Ionization of Water
Find the hydronium ion concentration of 1.4  10-3 M Ca(OH)2.
Ca(OH)2 → Ca OH-
1.4  10-3M  10-3M
[H3O+][OH-] = 1.0  10-14
[H3O+][2.8  10-3] = 1.0  10-14
[H3O+] = 3.6  M

6. pouvoir hydrogène (Fr.)
B. pH Scale 14 7
INCREASING
ACIDITY
INCREASING
BASICITY
NEUTRAL
pH = -log[H3O+]
pouvoir hydrogène (Fr.)
“hydrogen power”

7. pH of Common Substances
B. pH Scale
pH of Common Substances

8. pH = -log[H3O+] pOH = -log[OH-] pH + pOH = 14
B. pH Scale
pH = -log[H3O+]
pOH = -log[OH-]
pH + pOH = 14

9. B. pH Scale What is the pH of 0.050 M HNO3? pH = -log[H3O+]
Acidic or basic?
Acidic

10. B. pH Scale What is the pH of 0.050 M Ba(OH)2? [OH-] = 0.100 M
pOH = -log[OH-]
pOH = -log[0.100]
pOH = 1.00
pH = 13.00
Acidic or basic?
Basic

11. B. pH Scale
What is the molarity of HBr in a solution that has a pOH of 9.60?
pH + pOH = 14
pH = 14
pH = 4.40
pH = -log[H3O+]
4.40 = -log[H3O+]
-4.40 = log[H3O+]
[H3O+] = 4.0  10-5 M HBr
Acidic

12. C. pH Worksheet #6 7 = -log[H+] -7 = log[H+] [H+] = 1 x 10-7 M
A swimming pool has a volume of one million liters. How many grams of HCl would need to be added to that swimming pool to bring the pH down from to ? (Assume the volume of the HCl is negligible)
7 = -log[H+]
-7 = log[H+]
[H+] = 1 x 10-7 M
1,000,000L
Sol’n
1x10-7
mol H+
1 L
soln
= 0.1 mol H+
1,000,000L
Sol’n
1x10-4
mol H+
1 L
soln
-4 = log[H+]
[H+] = 1 x 10-4 M
= 100 mol H+

13. C. pH Worksheet #6 = 3642 g HCl 100 mol H+ – 0.1 mol H+ = 99.9 mol HCl
A swimming pool has a volume of one million liters. How many grams of HCl would need to be added to that swimming pool to bring the pH down from to ? (Assume the volume of the HCl is negligible)
100 mol H+ – 0.1 mol H+
= 99.9 mol HCl
99.9 mol HCl
36.46 g HCl
1 mol
HCl
= 3642 g HCl

14. D. pH Sig Figs
For the pH, the number of sig figs is shown by the # of decimal places
[H+] = 2.26 x 10-4 M =>
For the molarity from the pH, check decimal places in the pH
pH = =>
pH = 3.646
5.6 x 10-5 M