1. Understanding pH Sources:
1. Anthony Carpi, Acids, Bases and pH, Paul Decelles, The pH Scale, 6/20/2002

2. Water Molecule
H2O

3. H2O
H2O

4. Proton Exchange
H2O
HO- Hydroxide
H2O
H3O+ Hydronium

5. Proton Exchange
HO- Hydroxide
H2O
H3O+ Hydronium
H2O

6. High concentration of OH-
Base
Low concentration of H3O+

7. High concentration of H3O+
Acid
Low concentration of OH-

8. [H3O+] Concentration in moles/liter [OH-] Concentration in moles/literpH
[OH-] Concentration in moles/liter
Example
1  X 100
1  X 10-14
Battery acid, Strong HCl (4%)
1  X 10-1 1
1  X 10-13
Stomach acid
1  X 10-2 2
1  X 10-12
Lemon juice
1  X 10-3 3
1  X 10-11
Orange juice, Vinegar, Gastric juices
1  X 10-4 4
1  X 10-10
Acid rain, Tomato juice, Soda
1  X 10-5 5
1  X 10-9
Rainwater (unpolluted), Black coffee
1  X 10-6 6
1  X 10-8
Milk, Urine, Saliva
1  X 10-7 7
Pure water 8
Egg whites 9
Baking Soda 10
Tums® (antacid) 11
Ammonia 12
Mineral Lime 13
Bleach, Oven cleaner 14
Drano®, NaOH (4%)
Acid
Neutral
Base

9. [H3O+] Concentration in moles/liter [OH-] Concentration in moles/literpH
[OH-] Concentration in moles/liter
Example
1  X 100
1  X 10-14
Battery acid, Strong HCl (4%)
1  X 10-1 1
1  X 10-13
Stomach acid
1  X 10-2 2
1  X 10-12
Lemon juice
1  X 10-3 3
1  X 10-11
Orange juice, Vinegar, Gastric juices
1  X 10-4 4
1  X 10-10
Acid rain, Tomato juice, Soda
1  X 10-5 5
1  X 10-9
Rainwater (unpolluted), Black coffee
1  X 10-6 6
1  X 10-8
Milk, Urine, Saliva
1  X 10-7 7
Pure water 8
Egg whites 9
Baking Soda 10
Tums® (antacid) 11
Ammonia 12
Mineral Lime 13
Bleach, Oven cleaner 14
Drano®, NaOH (4%)
What is pH? pH is the opposite of the log of the concentration of Hydronium ions measured in moles per liter or pH = - log (concentration H3O+ )
- log (1 x 10-3 ) = 3
Examples
- log (1 x 10-7 ) = 7
- log (1 x ) = 11

10. [H3O+] Concentration in moles/liter [OH-] Concentration in moles/literpH
[OH-] Concentration in moles/liter
Example
1  X 100
1  X 10-14
Battery acid, Strong HCl (4%)
1  X 10-1 1
1  X 10-13
Stomach acid
1  X 10-2 2
1  X 10-12
Lemon juice
1  X 10-3 3
1  X 10-11
Orange juice, Vinegar, Gastric juices
1  X 10-4 4
1  X 10-10
Acid rain, Tomato juice, Soda
1  X 10-5 5
1  X 10-9
Rainwater (unpolluted), Black coffee
1  X 10-6 6
1  X 10-8
Milk, Urine, Saliva
1  X 10-7 7
Pure water 8
Egg whites 9
Baking Soda 10
Tums® (antacid) 11
Ammonia 12
Mineral Lime 13
Bleach, Oven cleaner 14
Drano®, NaOH (4%)
How much more acidic is orange juice than coffee? The answer is the ratio of the concentrations of H3O+.
Orange juice
Coffee
OJ is 100 times as acidic as coffee. This also implies that coffee is 100 times as basic as OJ.

11. Understanding pH Sources:
1. Anthony Carpi, Acids, Bases and pH, Paul Decelles, The pH Scale, 6/20/2002