Oceans 11
Properties of Sea Water
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No two oceans are alike;
o Ocean water is different depending on the location, season and time of day.
o Our oceans regulate our climate
Importance of Our Oceans
o They are our most important resource
o It acts as a sink (storage) for componds such as CO2, salts, minerals (ie calcium,
magnesium, iron) and heat.
o Supports all life on Earth
o Plankton is a major producer of oxygen and food for organisms in the ocean
o Contain currents that circulated the materials around the globe
o As the waters circulate, so does our weather.
Chemistry of water;
o Chemical formula: H2O
 2 Hydrogen and 1 Oxygen
o Polar molecule: H+, O Polarity comes from the positioning of the
electrons that make-up each atom
Surface tension;
o Water is a ‘sticky’ substance.
o Water molecules like to stay together.
o The molecule’s positive and negative charges attract other molecules
o The surface tension (attraction between molecules on the surface) is strong enough for
some organisms to walk on the top or bottom of the surface.
o Surface molecules are pulled toward the center
o It is for this reason that water forms rounded drops
Heat Capacity; (4.2J/g°C)
o Water has one of the highest abilities to hold heat
o This means that it can be heated without changing temperature
o It also means that it can store
Ocean Temperatures;
o Ocean surface temperature strongly correlates with
latitude
o Areas that get DIRECT sunlight heat up more than areas
that get indirect sunlight.
o Heat by DIRECT Sunlight;
Physical states of water;
o Only substance to be found on Earth in all three states –
solid, liquid, gas
o Solids: molecules vibrate weakly and are held in place
Oceans 11
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Liquids: molecules vibrate more rapidly and are able to move freely relative to each
other
o Gases: molecules are highly energetic and move independently of other molecules
Properties of Sea water;
o 0°C: freezing point (freeze, melt)
o 100°C: boiling point (vaporization, condensation)
o Water can , under low pressure, change from solid to gas without becoming a liquid
(sublimation)
o Heat also changes the density of the water
 Cold water is denser than warm water
o Differences in the density and salinity of ocean water makes deep ocean currents.
Composition of sea water;
o 5 major materials in ocean water
 the salts: from continent’s runoff
 Nutrients: materials that support plankton (nitrogen, phosphorus and silicon)
 Gases: oxygen, carbon dioxide, nitrogen
 Trace elements: minerals and elements from runoff, volcanic action, rock
materials (ie. Mercury, lead, zinc, calcium)
 Organic compounds: made by living organisms (sugars, proteins, fats)
o salinity changes with latitude due to variations in precipitation and evaporation.
o Areas with low precipitation and high evaporation will be saltier than areas that get a lot
of rainfall
Salinity: more salt= more dense
o Equator: heat evaporates water causing salinity to increase
o Poles: freezing of ice removes water, increasing salinity
Temperature: more cold = more dense
o Equator: heat causes water to become less dense
o Poles: cold causes water to become more dense
Thermocline, Halocline, Pynocline;
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Thermocline: graph showing the temperature changes with depth
Halocline: graph showing the salinity changes with depth
Pynocline: graph showing the density changes with depth