1. Acids and Bases When water dissociates,
hydrogen ions (H+) = hydroxide ions (OH-)
neutral solution (pH 7)

2. ex) HCl in gastric juices
Acidic Solutions
[H+] > [OH-]
sour
HCl H+ + Cl-
ex) HCl in gastric juices

3. Basic Solutions [H+] < [OH-] Bitter & slippery An example:
NaOH Na+ + OH-

4. The pH Scale
Ranges from
A pH below 7 is acidic [H+] > [OH-]
A pH above 7 is alkaline [OH-] > [H+]
A pH of 7 is neutral [H+] = [OH-]

5. The pH Scale

6. The pH Scale
Each unit change in pH represents a change of 10X

7. Buffers and pH
A buffer is a chemical(s) that keep pH within normal limits.
Bicarbonate ions (HCO3-) and carbonic acid (H2CO3) found in human blood buffers the pH to 7.4

8. If hydrogen ions (H+) are added to the blood, this reaction occurs:
H+ + HCO H2CO3
If hydroxide ions (OH-) are added to the blood, this reaction occurs:
OH- + H2CO3 HCO3- + H2O