1. Daily Warm-up Wednesday, October 1st
What bond connects oxygen to hydrogen to form a water molecule?
HW:
-Do pH lab
Turn in:
-Nothing (macromolecule lab after we finish discussing it)

2. Acids, Bases, pH

3. Water and pH pH=7 pH is the negative logarithm of hydrogen ions
Water molecules sometimes form ions
Pure water is neutral
pH=7
pH is the negative logarithm of hydrogen ions
log[H+]= pH

4. pH Scale More H+ than OH- is an acid More OH- than H+ is a base
Neutral has equal amounts

5. Buffer Weak acid or base that can prevent sharp, sudden changes in pH
Ex. Sodium bicarbonate

6. pH & Biology Acidic solutions = pH < 7 Basic solutions = pH > 7
Most biological fluids have pH 6 – 8
pH values in human stomach can reach 2
Each pH unit represents a 10-fold difference in H+ & OH- concentrations.
small change in pH is actually huge!
Based on work by K. Foglia

7. Example Questions Difference between pH of 3 and a pH of 4?
Which values are acidic, basic, or neutral?
Discuss with a partner

8. Why Do We Care?
Homeostasis
Oceans
Acid Rain

9. The Hydration of Carbon Dioxide in Water
CO2 + H2O H2CO3
⇌ HCO3- + H+
As carbon dioxide goes into solution, carbonic acid is formed, which partially dissociates, liberating protons (H+) and thus causing the solution to become more acidic, i.e., lowering the pH.