1. Lesson # 8 Acid Equilibrium Calculations
Chemical Equilibrium
Lesson # 8
Acid Equilibrium Calculations

2. Percent Ionization
When we calculate pH of acids, we generally can only do so directly if it is a strong acid.
This is because strong acids ionize completely in water, meaning that the concentration of hydrogen ions in solution is equal to the given concentration of the acid.
With weak acids, we first need to know the percent ionization.

3. Percent Ionization & pH
Percent Ionization = Concentration of Ionized Acid x 100% Initial Concentration of Acid = [H+] x 100%
[HA]
We can rearrange this to solve for [H+] (which will help us solve for pH):
[H+] = percent ionization x [HA]
100%

4. Example 1
A chemist prepares a 0.10 mol/L solution of methanoic acid. The pH of the solution is Determine the percentage ionization of the acid.

5. Example 2
A chemistry student prepares a solution of ethanoic acid, HC2H3O2, to a concentration of mol/L. If the percentage ionization of ethanoic acid is 1.3%, what is the acid ionization constant, Ka, for ethanoic acid?

6. Example 3
The standard value for the Ka of HF is 6.6x Calculate the pH of a 1.00 mol/L solution of HF.

7. Example 4
A solution of hypochlorous acid, HClO (aq), has a concentration of mol/L. If the pH of the solution is 4.23, calculate the Ka of hypochlorous acid.