1. pH and Living Things

2. Ionization of Water H2O H+ + OH-
Pure water will ionize (become ions) in the following way to create hydrogen, and hydroxide ions.
because of this, water has a neutral pH
H2O H+ +
OH-
water
hydrogen
ion
hydroxide

3. pH a system to measure the concentration of H+ ions in a solution
values range normally from 0-14
Neutral
H+ = OH–
pH values = 7
pure (distilled) water, salts (NaCl)

4. pH a system to measure the concentration of H+ ions in a solution
values range normally from 0-14
Acids
H+ > OH–
pH values < 7
lower number = more acidic = more H+

5. pH a system to measure the concentration of H+ ions in a solution
values range normally from 0-14
Bases
H+ < OH–
pH values > 7
higher number = more basic = more OH–

6. Water & Solutions

8. Water & Solutions

9. Buffers
weak acids or bases that prevent big changes in pH in organisms

10. Human Blood Buffing Example
bicarbonate (HCO3–) is used to keep the pH of your blood at 7.4
pH will range from
if blood gets too acidic, bicarbonate removes hydrogen ions
HCO3– + H+  H2CO3
if blood gets too basic, bicarbonate adds hydrogen ions to hydroxide to make water
HCO3– + OH–  CO3–2 + H2O

11. What property of life is than an example of?!?!
HOMEOSTASIS

12. pH Scale
each number represents a change in a factor of 10 on the pH scale
a solution with a pH of 5 has 10 times as many hydrogen ions (H+) as one with a pH of 6
pH 5 is 10 times more acidic than pH 6
a solution with a pH of 10 has 10 times as many hydroxide ions (OH–) as one with a pH of 9
pH 10 is 10 times more basic than pH 9

13. Example 1
How much more acidic is a solution with a pH of 2 than one with a pH of 5?
V V V
10 x 10 x 10
pH 2 is 1,000 times more acidic

14. Example 2
How much more acidic is a solution with a pH of 4 than one with a pH of 6?
V V
10 x 10
pH 4 is 100 times more acidic

15. Example 3
How much more basic is a solution with a pH of 12 than one with a pH of 8?
V V V V
10 x 10 x 10 x 10
pH 12 is 10,000 times more basic