pH Scale

1
pH Scale
2
What determines whether a solution is acidic,
neutral, or alkaline?

• The number of H ions.
• The number of OH- ions.
• H2O contains both

3
Acids pH 0-6

• Acids contain more H ions than OH- ions
• Carbon dioxide is acidic
• CO2 H2O H2CO3 or carbonic
  acid

4
Bases pH 8-14

• Bases contains more OH- ions than H ions

5
Neutral pH

• The number of H number of OH-
• pH 7
• Most reactions in our body take place at about a
  pH of 6.5 to 7.5

6
What is the pH?

• Litmus paper changes color with pH

7
What is the pH?

• Indicators can be used to test the pH

8
What is the pH?

• Limewater can be used to determine the pH.
• It turns cloudy in the presence of dissolved CO2.
• Limewater and phenol red turn a cloudy yellow in
  the presence of carbonic acid.

9
Who Cares?

• The presence of carbon dioxide indicates that an
  organism is living and making energy.
• 6 CO2 6 H2O ATP

10
Organisms make energy

• Using oxygen in air
• Using glucose from plants

11
Are these organisms making energy?
12
How would you know?