1. Water, pH notes Properties of water 1. polarity 2. cohesion
3. adhesion
4. stable temp.
5. expands when freezes
Acids, bases
A. pH
1. acid
2. base
3. neutral
B. Buffers
III. Organic

2. Summary Section 2 – pages 152-156
Water and Its Importance
Water is—The most important compound in living organisms
Water—makes up % of most organisms.
Ex. Blood and sap are mostly water
Summary Section 2 – pages

3. Unique Qualities of Water
1. Polarity: uneven distribution of electrons between the oxygen and hydrogen atoms, oxygen is -, hydrogen is +

4. 2. Cohesion Water attracted to other water molecules
Water molecules act like stretched film on water surface
Water beads up on waxy leaf, no attraction to leaf
Also called surface tension

5. 3. Adhesion
Water creeps up thin tubes because of attraction to other substances
Allows plants to get water from roots to leaves
Also called capillary action

6. 4. Water resists temperature changes
Requires a lot of heat to increase water temperature
Helps cells to have a constant temperature

7. Summary Section 2 – pages 152-156
5. Water expands when it freezes
Very unique to water
Summary Section 2 – pages
Ice takes up more volume than water
Ice is less dense than water so it floats

8. Acids, Bases, and pH
pH—a measure of how acidic basic or solution is, scale ranges from 0-14
Acid--substance with pH below 7, forms hydrogen (H+) ions in water
Base—substance with pH higher than 7, forms hydroxide (OH-) ions in water

9. Neutral: solution with pH = 7, concentration of H+ ions and OH- ions are equal

10. Which is a stronger acid, pH 2 or pH5?
Which is a stronger base, pH 8 or pH 12?

11. Examples
If dissolved in water, will these compounds be acidic, basic, or neutral?
1. C9H8O4
2. Mg (OH)2
3. Ca CO3

12. Buffers
Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH
Help maintain homeostasis

13. Organic Derived from something living or once living
Contains carbon (exception: carbon dioxide)
Are the following organic or inorganic?
C6H12O6 H2O CH4 CO2