1. The Extraordinary Properties of Water
Courtesy of Kate Morkeski

2. The extraordinary properties of Water
A water molecule (H2O), is made up of three atoms: one oxygen and two hydrogen. H O 1

3. 10

4. The extraordinary properties of Water
At sea level, pure water boils at 100 °C and freezes at 0 °C.
The boiling temperature of water decreases at higher elevations (lower atmospheric pressure). PV=nRT
For this reason, an egg will take longer to boil at higher altitudes. 1

5. The extraordinary properties of Water
Cohesion
Adhesion
High Specific Heat
High Heat of Vaporization
Less Dense as a Solid 1

6. Cohesion
Cohesion is the property of water that causes it to be attracted to itself.
Surface tension, a measure of the strength of water’s surface, is the direct result of cohesion.
The strong film on the surface of water is a result of the attraction between water molecules. This property allows insects to walk on the surface of water and the creation of waves. 1

7. Water strider

8. Cohesion 1

9. Adhesion
Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.
Water molecules will “tow” each other along when in a thin glass tube. This is called capillary action. This is the same process by which plants and trees remove nutrients from the soil, and paper towels soak up water. . 1

10. Adhesion 1

11. High Specific Heat
Water resists temperature change, both for heating and cooling.
Water can absorb or release large amounts of heat energy with little change in actual temperature. 1

12. “Water vapor forms a kind of global ‘blanket’ which helps to keep the earth warm. Heat radiated from the sun-warmed surface of the earth is
absorbed and held
by the vapor.” 1

13. High Heat of Vaporization
In order for water to evaporate, hydrogen bonds must be broken. As water evaporates, it removes a lot of heat with it.
Thus, the heat of vaporization refers to the amount of energy required to convert water from a liquid to a gas. 1

14. High Heat of Vaporization
Meteostat 5 water Vapor Imagery morning of 9/5/2004
Courtesty of 1

15. Water is Less Dense as a Solid
Ice is less dense as a solid than as a liquid.
Liquid water has hydrogen bonds that are constantly being broken and reformed.
Frozen water forms a crystal-like lattice whereby molecules are set at fixed distances. 1

16. Water is Less Dense as a Solid
Which is ice and which is water? 1

17. Water is Less Dense as a Solid
Ice 1

18. Density of water
If density of object is = to or < than water it will float.
If the object’s volume displaces an amount of water equal to the weight of the object it will float.
Displacement is how steel ships can float even though the density is greater.
Density of pure water is 1.0
Density of pure ice is 0.92.
Density of sea water is 1.03.
Icebergs are made of pure water will float with a ratio of more ice above the surface than that of an ice cube.

20. The extraordinary properties of Water
Why talk about water?
In the fossil record, in what habitat do we first observe life? 2

21. Homeostasis Steady state
Constant physiological condition of cells, organisms global ecosystems
a. Makes a good insulator
b. Resists temperature change
c. Universal solvent
d. Coolant
e. Ice protects against temperature extremes 4

22. Bond Types
Covalent
Hydrogen
Electrostatic
Van der Waals 9

23. Implication of Hydrogen Bonding
Ice floats: density of solid water is less than liquid
Cohesion: the intermolecular forces between particles of a substance, in this case, water
Adhesion: the intermolecular forces between two different substances, water and paper or glass or xylem. 12

24. Implication of Hydrogen Bonding
Specific heat: Water resists change in temperature. Heat energy is used to break H-bonds. Specific heat is amt. of heat that must be absorbed or lost for 1 g. of the substance to change temp. by 1C.
Heat of vaporization: amount of energy required to convert 1 gram of a substance from a liquid to a gas 13