1. Properties Of Water And Sea Water
Class The Oceans
Properties Of Water And Sea Water
Why is water such an unusual substance?
Structure of the H2O molecule
States of H2O, and energy transfer in changes of state
Density, and effects of temperature
Sea water -- the effect of dissolved salts

2. The Water Planet

3. The Most Important Driver of Earth Surface Processes
WATER (H2O):
The Most Important Driver of
Earth Surface Processes
Most common substance at the surface
Less common on the surface of other planets
Essential for life
Unusual properties
Excellent solvent for ions
Absorbs (and releases) large amounts of energy
Regulates climate

4. The Water Planet

6. STRUCTURE OF H2O MOLECULES
Non-linear --> electrically "polar"
+ and - charged ends
"H-bonding" = attraction, + and -
Unusual properties result from this
Strong solvent for ions
Charges attracted by charged ends of the water molecules

9. STATES (PHASES) OF H2O
Ice -- All H2O’s are H-bonded in an orderly crystal structure
Liquid Water -- H2O’s about as close as in Ice, BUT
not rigidly held
free to move somewhat
Vapor -- Free molecules, far apart

14. Energy Absorbed Or Released
In H2O Phase Changes
Ice <--> Water calories/gram
Water <--> Vapor -- nearly 600 cal./gram
Large amount!

15. Why so much energy?
Evaporation
--> energy required to break H-bonds
Condensation
--> energy liberated when H-bonds form
So... Water is an efficient means of moving heat energy around (as you well know!!!)

17. Water vapor = “latent” heat

18. Heat on the earth- Huge role for water vapor
Evap. of sea water --> water vapor in air
Cools the ocean
Heat energy transferred to water vapor
Water vapor moved to higher latitude
Condensation of water vapor: WARMS the atmosphere; main way heat is transported from low to high Latitude

19. Water vapor = “latent” heat

21. HEAT CAPACITY (= specific heat)
How much energy is needed to heat up a substance...OR
How efficiently heat is stored in a substance
Definition: "Energy required to raise the temperature of one gram of the substance by 1˚C.”

22. WATER HAS A LARGE HEAT CAPACITY
1 calorie / g - ˚C ... very high!
Rocks and soils = 0.2 cal. / g - ˚C.
Consequences of this difference...
Oceans and lakes gain/lose much heat with little T change (moderates T)
Land heats and cools much more easily

24. Warmer = less dense, right?
Density
Warmer = less dense, right?

25. DENSITY Mass per unit volume, e.g., grams/cm3
Pure water (at 4˚C) = g/cm3
Ice = 0.92 g/cm Less than liquid ...unusual!
Sea water = g/cm3
Large water bodies tend to be stratified (= layered)
Top layers -- least dense
Bottom layers -- most dense