What are the Properties of
Seawater?
IN:
1.
2.
Glue in the handouts as shown on pages
86 and 87.
How does adding salt to water change its
properties?
6-Square Notes w/ Summary
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What are the Properties of Seawater?
Pages 84 - 87
Solutions and Mixtures in Water

A solution occurs when the molecules of one
substance are homogeneously dispersed
among the molecules of another substance.



The SOLVENT is the substance that does the
dissolving (this is water in the ocean).
The SOLUTE is the substance that is dissolved
(these are the salts and other substances that
water can dissolve).
A mixture occurs when two or more
substances closely intermingle, yet retain their
individuality.
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What are the Properties of Seawater?
Salts and Salinity




Salinity includes the total quantity of all dissolved
inorganic solids in seawater.
Sodium chloride (rock salt or halite) is the most
common and abundant sea salt.
Scientist’s measure salinity in various ways –
expressed in parts per thousand (‰ or ppt).
 The average salinity of the ocean varies from 35‰
to 37‰.
The ocean’s salinity varies from near zero at river
mouths to more than 40‰ in confined, arid regions.
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What are the Properties of Seawater?
Salt – In It’s Solid Form
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What are the Properties of Seawater?
The Colligative Properties of
Seawater

Colligative properties are properties of a
liquid that may be altered by the presence of a
solute and are associated primarily with
seawater.

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Pure water doesn’t have colligative properties.
Fresh water, with some solutes, can have
colligative properties to some degree.
What are the Properties of Seawater?
Salt Water Properties

Ability to conduct an electrical current. A
substance that can do this is called
an electrolyte.

Decreased heat capacity. Takes less heat to
raise the temperature of seawater.
 Raised boiling point. Seawater boils at a
higher temperature than pure fresh water.
 Decreased freezing temperature. Seawater
freezes at a lower temperature than fresh
water due to increased salinity.
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What are the Properties of Seawater?
Salt Water Properties



Slowed evaporation. Seawater evaporates more
slowly than fresh due to the attraction between ions
and water molecules.
Ability to create osmotic pressure. Liquids flow or
diffuse from areas of high concentration to areas of
low concentration until the concentration equalizes.
Osmosis occurs when this happens through a
semi-permeable membrane, such as a cell membrane.
Because it contains dissolved salts, water in seawater
exists in lower concentration than in fresh water.
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What are the Properties of Seawater?
Osmotic Pressure
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What are the Properties of Seawater?
Proportions of Ions in Seawater
Next to
hydrogen and
oxygen,
chloride and
sodium are
the most
abundant
chemicals in
seawater.
11/21/2011
What are the Properties of Seawater?
OUT:
 What
are the colligative properties
of Seawater?
 Does fresh water have these
properties?
11/21/2011
What are the Properties of Seawater?