The Properties of Sea Water
What makes water so special?
Why is the ocean salty?
Where’s the Water?

Reservoir Volume (10
6
km
3
) Percent
Ocean 1370 97.3
Ice (polar) 29 2.1
Groundwater 5 0.4
Lakes 0.1 0.01
Atmosphere 0.01 0.001
Rivers 0.001 0.0001
Where did the water in the
Oceans come from?

Outgassing (H
2
O, CO
2
) of the Earth
from volcanoes, early in its history,
but continuing today

Sedimentary rocks as old as 3.8
billion years!

A much smaller amount from comets

vapor)

ice
ice
water vapor
water vapor
liquid water
liquid water
Exists in three states on the planet surface
Exists in three states on the planet surface
Changes of state
Water co-exists on the Earth in 3 physical states: Habitable Planet
solid
solid
liquid
liquid
gas
gas
Changes of state always occur
Changes of state always occur
at
at
constant temperature
constant temperature
The heat needed for a change of state
The heat needed for a change of state
is called
is called
latent heat
latent heat

Major source of energy to power
Major source of energy to power
the Earth’s weather systems
the Earth’s weather systems
Density of Pure Water
Consequences…
Consequences
Bottom temperature of deep, cold lakes is always
4
o
C.
Ice floats on the water surface, so fish survive.
Pipes (or beer bottles) can freeze and burst.
Surface tension
Surface tension-
-
measure of how
measure of how
difficult it is to stretch or break the
difficult it is to stretch or break the
surface of a liquid
surface of a liquid
Water has the highest surface tension of all common liquids
Water has the highest surface tension of all common liquids
Special Properties of Water

Density of solid is less than liquid

) 19.0 g/kg

Sodium (Na
+
) 10.6 “

Sulfate (SO
4
2-
) 2.6 “

Magnesium (Mg
2+
) 1.2 “

Calcium (Ca
2+
) 0.4 “

Potassium (K
+
) 0.4 “
35.2 g/kg
Ions in Sea Water

Anions are negatively charged
examples: Cl
-
, SO
4

Terrigenous input (rivers, dust, ash)

Hydrothermal vents

Dissolving old sediments (evaporites)

Steady State: Inputs equal Outputs