1. Ways to measure Acidity/Basicity What is pH? What is pOH?
pH and pOH
Ways to measure Acidity/Basicity
What is pH?
What is pOH?

2. What is pH? pH = potential Hydrogen
The pH scale measures how acidic or basic a substance is, is logarithmic
The pH scale ranges from 0 to 14.
A pH of 7 is neutral.
A pH less than 7 is acidic, greater than 7 is basic.

3. Basic Equations
pH + pOH = 14 Kw = [H+] [OH-] = 1 x

4. Calculating pH Values pH = 14 – pOH pH = - log [H+]
Example: Calculate pH given [H+] = 1.4 x 10-5 M
pH = - log [H+]
pH = - log [1.4 x 10-5]
pH = 4.85

5. Calculating [H+] values
EXAMPLE: Find [H+] if pH = 8.5
[H+] = 10-pH

[H+] =

[H+] = 3.2 x 10-9 M

6. Calculating pOH pOH = 14 – pH pOH = -log[OH-]
EXAMPLE: What is the pOH of a solution that has a hydroxide ion concentration of 4.82 x 10-5 M ?
pOH =  - log [OH-]
pOH =  - log [4.82 x 10-5]
pOH = 4.32

7. YOU TRY! pH = 4 7.1 = -log [H+] 10 – 7.1 = [H+] = 7.9 x 10-8 M
Find the pH of the solution if [H+] = 1 x 10-4 M
What is the hydrogen ion concentration if pH = 7.1?
What is the pH if [OH-] = 4 x M?
pH = 4
7.1 = -log [H+]
10 – 7.1 = [H+] = 7.9 x 10-8 M
pOH = -log [OH-]
pOH = -log [4 x ] =