2. Acid-Base Equilibria Review: In pure water & all aqueous solutions:
H2O + H2O = H3O+ + OH-

3. Solutions of Strong Acids/ Bases:
0.10 M HNO3 actually consists of M H3O or [H3O+] = 0.10 M
0.10 M NaOH…. Adds 0.10 OH- to the water solution

4. Solutions of Weak acids/bases
0.10 M HC2H3O2 : a weak acid- when it reacts with water it does not ionize 100%.
What is the [H3O+] for this solution? Ka = 1.8 x 10-5

5. Weak acids (continue) [H3O+] [C2H3O2-] Ka = = 1.8 x 10-5 [HC2H3O2]

6. Weak acids (continue)
So…. 2 =
1.8 x 10-5

7. Weak bases….
B H2O = BH OH-
NH H2O =

8. Weak bases (continue)
If the [OH-] = 2.5 x , what is the [H3O+]?

9. pH
A simple scale for ranking the H3O+ concentrations of dilute acid/base solutions. (Sorenson).
The logarithm of a number is that number expressed as an exponent of the base 10.
For example, the logarithm of 1 is 0, 1 x 100.

10. pH Scale [H3O+][OH-]= 1x10-14 pH = - log[H3O] pH + pOH = 14
Formulas to remember

11. More About the pH Scale Given a 3.25 x 10-4 M HNO3 , solve for: [H3O+]
[OH-]

12. Sample Problem 1.8 x 10-5 What is the pH of a 0.10 M HC2H3O2 solution?=
1.8 x 10-5
Ka =
[HC2H3O2 ]