Properties of Water
Marine Science Notes Series
Water Molecule and Bonding Forces
I. London Forces: Intramolecular
a) Covalent Bonds: sharing of electrons
between Hydrogen and Oxygen
b) Van der Waals – forces within the
water molecule
c) Hydrogen Bonds – keeping a network
of water molecules together (~105 0 angle)
Energy & Water
• Heat Values are measured in calories and
joules.
a) a calorie is the amount of heat energy
needed to raise the temperature of 1 gram of
water by 10C
This is sometimes called specific heat
b) There are energy values when water
changes state from a solid to a liquid to a gas
(Latent Heat of… Fusion and of Vaporization)
c) Temperature is an indirect function of heat
energy
F= 9/5 C + 32
C = 5/9 (F – 32)
Specific Heat of Salt Water?
• We will calculate the specific heat of salt
water, but will see how accurate we are by
determining the specific heat of a known
metal
Heat Loss or Gain = m (Cp) T
Cp = Specific Heat
Special Properties of Water
a) Water can break salts down into ions
(which are charged particles)
Cations are positive ions
Anions are negative ions
b) Cohesion – This holds a water molecule
together as a “body”
c) Adhesion – the ability of water to bond
with other molecules
d) Viscosity – the ability of a liquid to flow
e) Density – varies with temperature*
Seawater
• The density of seawater at 4 oC is
approximately 1.0278 g/cm3
• The freezing point of seawater is -1.33 oC
• Open ocean water has a salinity of 35 g/kg
Eleven Major Constituents
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Chloride
Sulfate
Bromide
Bicarbonate
Fluoride
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Residence Time of Chloride is 80 million years
Residence Time of Sodium is 60 million years
Boron
Strontium
Calcium
Potassium
Magnesium
Sodium
Light and Seawater
• Visible light ranges from 350 to 720 nm as
part of an electromagnetic light visibl
emission
-In the first 1 meter – 60% of light is
absorbed
-In the first 11 meters, 80% of light is
absorbed
-Below 1000 m, no light penetrates
Attenuation
Nature Reviews Microbiology 2007
Gases in water
• Solubility is determined by
– Temperature
– Salinity
– Density
It is measured in mg/L or ppm. The understood
gases are Oxygen and Carbon dioxide