Properties of Water
Unit 2
I. Water Is A Solvent
A. Solvent – substance doing the
dissolving
B. Solute – substance being
dissolved
C. Major difference in freshwater
and sea water is presence of salt
(NaCl)
II. Structure of Water
A. Pure H2O – two hydrogen
and one oxygen.
B. Salt Water – Six elements
and compounds comprise about
99% of sea
salts.
III. pH of Water
A. H2O can separate into
H+ and OH- ions.
B. The presence of these
ions cause water to
become acidic or basic.
C. pH of pure water – 7
“neutral”
IV. Dissolved Oxygen in Water
A. Oxygen is found in water even
though it does not dissolved easily.
B. Dissolved oxygen is measured in
parts per million (ppm).
C. Ocean water can hold from 1 to 12
ppm depending on the temperature
of the water.
(oxygen in air is 200 ppm)
V. Sea Water
A. Ocean water is made up of about
96.5 percent water molecules and
3.5 percent NaCl (table salt).
B. Calcium Carbonate is also a
common compound found is the
seas.
VI. Salinity
A. Oceanic waters typically have
35g of salt dissolved in 1000g of
water (3.5%).
B. Salts accumulate in the oceans as
rain leach sediments from
the land.
VII. Temperature
A. Ocean water temperatures
vary between -2 to 30°C.
B. Temperatures below 0ºC are
possible because salt water
freezes at colder
temperatures than pure
water.
VIII. Pressure
A. Organisms on land experience
atmospheric pressure.
B. Marine organisms experience
water pressure and
atmospheric pressure.
4
5
6
20m 30m 40m 50m
3
8
9
60m 70m 80m
7
1. Atmospheric
pressure: atm
2. With each 10m (33ft)
of increased depth,
another atmosphere of
pressure is added.
m 10m
1atm 2
C. Units of Pressure
90m
10atm
IX. Buoyancy an upward force exerted
by a fluid an object is in.
X. Density
A. Mass of a substance per unit of
volume.
B. Formula: D= m/v
C. Unit: g/ml or g/cm3 (ml = cm3)
D. Density of Pure H2O = 1 g/ml
(impurities in water cause the
density to increase)
E. Principle of Density
1. Objects of greater density than
the fluid they are in – will sink
in the fluid.
2. Objects of lesser density than
the fluid they are in – will
float in the fluid.