1. WARM UP
What is the pH of a M weak acid (HA) solution that is 8.2% ionized?

2. Acid/Base Weak pH
Chemistry II

3. Calculating pH with K
Use the K value, concentration of solution, and an ICE Table to solve for concentration of H+/OH- at equilibrium
Can also find pH
Example:
.036M HNO2 (Ka = 4.5 x 10-4)
HNO H+ + NO2-
What is the pH?

4. Calculating pH with K Process Molarity = initial concentration
Use change of x
Set up K
Solve for x (quadratic?)
Plug x into concentration values
Use concentration to find pH
Initial [HNO2] = .036
Eq: [HNO2] = .036 – x
[H+] = x [NO2-] = x
K = [x] [x]
[.036 – x]
x = 4.0 x 10-3
[H+] = 4.0 x 10-3
pH = -log 4.0 x 10-3
pH = 2.42

5. Titrations
Use K value to calculate exact H+ or OH- concentrations for your standard
Compare to unknown that was titrated
Ex:
35 mL of 2.5 M HNO2 is used to titrate 13 mL of NaOH. Concentration of NaOH is…

6. WARM UP
What is the H+ ion concentration in a .82 M solution of HOCl? The Ka value for HOCl is 3.2 x 10-8.