WATER by gjjur4356

VIEWS: 15 PAGES: 15

									   WATER
Nature’s Magician
 Water

 H 2O

H—O—H
           Invisible & Visible

• Canada has approximately 7% of the
  world’s renewable freshwater supply.
• Unlike most substances, water is less
  dense as a solid and therefore floats.
• Water vapour forms a ‘solar blanket’
  – Heat radiated from the earth is trapped in this
    thermal blanket
                 Attraction



• Water molecules are attracted to each
 other and form hydrogen bonds.
  – these bonds are responsible for all of waters
    physical and chemical properties
                   Adhesion
• Water molecules bind to many surfaces.

• Capillary action
  – Water molecules adhere to the side of the
    material and they pull other water molecules
    with them.
  – The water surface pulls the entire body of
    water with it until the downward force of
    gravity is too great to overcome.
     • Think of a way capillary action is used in everyday
       life.
• What will happen to
  the water in the
  container? Draw a
  second diagram.
    Water and it’s 3 states:

• Take a minute to sketch the
 arrangement of water molecules in a
 solid, liquid and gas.
        The Universal Solvent

• Perhaps the most important property of
  water.
  – Is there a substance on earth that is not
    soluble in water?


• If it were not for this property, life would
  not be possible on earth. Why?
    Discuss with your group. Be prepared to
    share with the class.
         Boiling and Freezing

• Pure water- boils at 100°C
                freezes at 0°C
• At higher elevations the boiling point for
  water decreases.
• If a substance is dissolved in water, the
  freezing point is lowered.
  – Can you think of a practical application of this
    knowledge?
         Thermal Properties

• Water absorbs or releases more heat than
  many substances
• When the temperature of a lake or river is
  different from the surrounding air, than a
  mist or fog is produced.
  – This occurs when the lake has cooled the
    surrounding air enough to cause saturation
    (water droplets are suspended).
• Large bodies of water (e.g. oceans or the
 Great Lakes) have a profound influence on
 climate.
  – World's great heat reservoirs and heat
    exchangers
  – Source of much of the moisture that falls as
    rain and snow over adjacent land masses.
• When water is colder than the air,
 precipitation is curbed, winds are reduced,
 and fog banks are formed.
            Surface tension
• Due to the unique attraction between
  water molecules, a strong surface film is
  produced.
• This film or tension allows water to
  support objects heavier and denser than
  itself.
• Surface tension is critical in the formation
  of waves. Without it the energy from
  wind could not be transferred to the
  water.
  – Why are waves important?
    Did you know???
• Raindrops are not tear-shaped. Scientists,
  using high-speed cameras, have
  discovered that raindrops resemble the
  shape of a small hamburger bun.
• The average human body is composed of
  about 55% water.
• Life on earth probably originated in water.
• More than half of the world's animal and
  plant species live in the water.
        Homework

• Find out 5 more interesting or surprising
 facts about water.

  – You will be sharing your findings in class.

  – Be sure to include the source of your
    information.
               Resources

• Environment Canada http://www.ec.gc.ca/
  Sept. 17, 2007.
• Images- Clip Art (Microsoft Office 2003)

								
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