Properties 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 Water
Water is polar ….
Remember…. Water has 2
hydrogen atoms and one oxygen
atom H2O
(–)
_
Hydrogen bond
(+)
H
O
H
+
(+)
O
(–)
H
(–)
H
(+)
(–)
+
(+)
Properties of Water
cohesion
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).
Properties associated with polarity/ adhesion, cohesion
• Capillary Action
• Surface Tension
• Transpiration
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 Water
cohesion
adhesion
density
High specific heat
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 below
o allowing life to survive the winter
Properties of Water
cohesion
adhesion
density
High specific heat
pH
An example is the more moderate climate of a coastal location
compared to one far inland.
Properties of Water
cohesion
adhesion
density
High specific heat
pH
pH
pH 0
More
acidic…more
H ions
neutral
pH 7
water
More
basic…more
OH ions
pH 14
Most biological fluids have a pH b/w 6 and
8 …. But stomach can reach a pH of 2
Properties of Water
cohesion
adhesion
density
High specific heat
pH