The Importance of Water - PowerPoint PPT Presentation

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The Importance of Water

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Title: PowerPoint Presentation Author: Crystal Last modified by: Crystal Created Date: 10/6/2002 11:35:01 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: The Importance of Water


1
The Importance of Water
2
Water The Facts
  • Water is possibly the most important compound in
    living organisms.
  • Water consists of 1 atom of oxygen combined with
    2 atoms of hydrogen.
  • Water makes up 70 to 95 percent of most organisms.

3
What are the characteristics of water?
  1. Water is polar.
  2. Water molecules attract other water molecules.
    This property is cohesion.
  3. Water displays adhesion.
  4. Water expands when it freezes.

4
Water is Polar
  • A polar molecule has an unequal distribution of
    charge-each molecule has a positive end and a
    negative end.
  • All polar substances are attracted to other polar
    substances.

5
Why is this polarity important?
  • Polar water molecules attract other water
    molecules as well as ions and other polar
    molecules.
  • Because of this attraction, water can dissolve
    many ionic compounds, such as salt and polar
    molecules like sugar.

6
How do water molecules attract?
  • Water molecules form hydrogen bonds.
  • Hydrogen bonds are weak bonds that form between
    the positively charged hydrogen atoms of one
    water molecule and the negatively charged oxygen
    atoms of another water molecule.
  • This ability of water molecules to stick together
    is called cohesion.

7
Also due to its polarity
  • Water displays the property of adhesion which is
    the ability of one substance to cling to another.
  • Examples of adhesion include waters ability to
    creep up thin tubes. Plants show this property
    when they send water from the soil up through
    their tissues.

8
And finallywater expands when it freezes.
  • Because of this property, ice is less dense than
    liquid water.
  • This property can be seen when ice forms and
    floats on the surface of a pond.

9
Water to drink
  • 66 of the human body is made up of water.
  • At just 2 dehydration your performance decreases
    by around 20.
  • We should drink at least 1½ litres of water a day.

10
Water Diseases
  • 80 of all illness in developing countries is
    caused by water related diseases.
  • 90 of wastewater in developing countries is
    discharged directly into rivers and streams
    without treatment.

11
Water World
  • Two thirds of our planet is covered by water.
  • 97.5 of the water is saltwater.
  • The majority of freshwater is beyond our reach,
    locked into polar snow and ice.

12
Clean Water
  • The number of people with access to clean water
    has doubled in the last 20 years.
  • 1.1 billion people in the world still do not have
    access to safe water. This is nearly 20 of the
    population.

13
World Water Uses
14
Saving Water
  • Do you leave the tap on when you clean your
    teeth? You waste 5 litres of water.
  • You only need ¼ litre!

15
Bath or Shower Water?
  • An average bath uses 80 litres of water.
  • An average shower only uses 35 litres.

16
Water Future
  • The UN estimates that by 2025, 75 of the world
    population wont have reliable, clean water.
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