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Properties of WaterProperties of Water
Water covers 2/3 of Earth• 97% Saltwater oceans• 2.4% Ice (polar caps and glaciers)• 0.6% Surface water (lakes and streams)
The Human body is made of ~80% water.• To function properly, the body requires between one and
seven liters of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors.
• Most of this is ingested through foods or beverages other than drinking straight water.
Properties of WaterProperties of Water
Remember…. Water has 2 Remember…. Water has 2 hydrogen atoms and one oxygen hydrogen atoms and one oxygen atom atom H2O
OHH
_
++
Hydrogen bond(+)
(+)
H
H(+)
(+)
(–)
(–)
(–)(–)
O
Water is Water is polarpolar …. ….
Properties of WaterProperties of Watercohesion
adhesion
High specific heat
density
pH
Cohesion• The natural attraction of a water molecule to other
water molecule is called cohesion.
Adhesion• The attraction of a water molecule to another polar
molecule is adhesion.
water droplets on a spider’s web (polar surface).
Capillary Action
Surface Tension• At the surface of the drop of water, water does not
attract to the air….. Surface tension
Jesus Lizard
Transpiration
Properties of WaterProperties of Watercohesion
adhesion
High specific heat
density
pH
Density
Why is “ice floats” important??
if ice sank…..o eventually all ponds, lakes, and even ocean would freeze solid o during summer, only upper few inches would thaw
surface ice insulates water belowo allowing life to survive the winter
Properties of WaterProperties of Watercohesion
adhesion
High specific heat
density
pH
An example is the more moderate climate of a coastal location compared to one far inland.
Properties of WaterProperties of Watercohesion
adhesion
High specific heat
density
pH
pH
pH 7
pH 14
pH 0
neutral
More acidic…more H ions
More basic…more OH ions
water
Most biological fluids have a pH b/w 6 and 8 …. But stomach can reach a pH of 2
Properties of WaterProperties of Watercohesion
adhesion
High specific heat
density
pH
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