1. Unit 2: Biochemistry Chapter 2
pH Scale
Unit 2:
Biochemistry
Chapter 2

2. pH Scale
In an aqueous solution some water and other molecules tend to ionize
Ex: H2O  H+ (hydrogen ion) and OH- (hydroxide ion)
The concentration of H+ is used to calculate pH
The pH scale ranges from

4. Acids Solution that has a high concentration of H+ ions
Chemical formula usually begins with H
Has a pH of 6.9 or less
Examples: HCl, H2SO4, HNO3, HCH3O3

5. Bases
Solution that has a low concentration of H+ (high concentration of OH-)
Chemical formula usually ends with OH
Has a pH of 7.1 or higher
Examples: NaOH, KOH, Mg(OH)2

6. Water Water is neutral (pH = 7) If an acid is added to water…?
If a base is added to water…?

7. Buffers
Substance that keeps the pH relatively stable when an acid or base is added.
Most biological solutions have a natural ability to buffer: blood, milk, saliva, egg white
Chemical reactions in living things depend on a stable pH

8. Additional Resources