Ch. 19 Acids & BasesCh. 19 Acids & Bases

II. pHII. pH

A. Ionization of WaterA. Ionization of Water

H2O + H2O H3O+ + OH-

Kw = [H3O+][OH-] = 1.0 10-14

A. Ionization of WaterA. Ionization of Water

Find the hydroxide ion concentration of 3.0 10-2 M HCl.

[H3O+][OH-] = 1.0 10-14

[3.0 10-2][OH-] = 1.0 10-14

[OH-] = 3.3 10-13 M

Acidic or basic?Acidic

pH = -log[H3O+]

B. pH ScaleB. pH Scale

0

7INCREASING

ACIDITY NEUTRALINCREASING

BASICITY

14

pouvoir hydrogène (Fr.)“hydrogen power”

B. pH ScaleB. pH Scale

pH of Common SubstancespH of Common SubstancespH of Common SubstancespH of Common Substances

B. pH Scale - FormulasB. pH Scale - Formulas

pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14

B. pH ScaleB. pH Scale

What is the pH of 0.050 M HNO3?

pH = -log[H3O+]

pH = -log[0.050]

pH = 1.3

Acidic or basic?Acidic

B. pH ScaleB. pH Scale

What is the molarity of HBr in a solution that has a pOH of 9.6?

pH + pOH = 14

pH + 9.6 = 14

pH = 4.4

Acidic

pH = -log[H3O+]

4.4 = -log[H3O+]

-4.4 = log[H3O+]

[H3O+] = 4.0 10-5 M HBr