Water makes up a large percentage of the human body and Earth. It has several unique properties that are essential for life. Water is an excellent solvent that can dissolve many substances, enabling nutrients to be transported in living things and waste removed. It has a high specific heat, allowing it to buffer temperatures without much change in its own temperature. Solid water (ice) is less dense than liquid water, meaning ice floats, which prevents aquatic life from being trapped under frozen surfaces. These properties make water well-suited as the medium for life on Earth.

1. THE UNIQUE
PROPERTIES OF WATER
Cherides P. Mariano

2. Human cells – 70%
Blood - 80%
Whole body – 60-70%
On earth – around 75%-
78%

3. 1.WATER IS A GOOD SOLVENT
It can dissolve a large variety of chemical
substances.
It dissolves salts, ionic compounds, polar
covalent compounds like alcohols and
organic substances capable of forming
hydrogen bonds with water.
Gases like O2 and CO2 dissolves in water

4. Benefits:
-enabling it to carry dissolved nutrients into
tissues of living organisms and flush waste
products out
-plants are able to absorb nutrient ions
dissolved in water
Issue:
-ease of pollutants from farming and
industrial plants to be dissolved in water
1.WATER IS A GOOD SOLVENT

5. 2.WATER HAS A HIGH SPECIFIC HEAT
Specific Heat – the amount of heat or energy
needed to raise the temperature of 1g of a
substance by 10C.
- specific heat of water is 1 calorie/g-0C
(4.18J/g-0C)
. Water resists temperature change, both for
heating and cooling. Minimizes the abrupt
temperature changes in the organisms.
 Water can absorb (IMF breaks) or release
large amounts of heat energy (IMF forms)
with little change in actual temperature.

6. Benefits:
- large bodies of water to help
moderate the temperature on earth.
-changing climate
-capacity of bodies of water as
temperature buffer
FYI: It takes about 4.5 times greater amount of energy to
heat up water than an equal amount of land.
Hence, large bodies of water heat up and cool down more
slowly than adjacent land masses.

8. PROPERTIES OF WATER
 Water has higher melting & boiling points than other liquids of
approximately the same molecular weight.
 Compound MW(amu) MP(0C) BP (0C)
 H2O 18 0 100
 CH4 16 -184 -162
 NH3 17 -78 -33
 CH2O 30 -92 -21
Inference: Water can exist as a liquid over a wide range of
temperature, and can remain as liquid in most climates on
the earth’s surface.

9. PROPERTIES OFWATER
 3. Solid water is less dense, and in fact floats on
liquid water
 When solid water forms, the hydrogen bonds
result in a very open structure with unoccupied
spaces, causing the solid to occupy a larger
volume than the liquid.This makes ice less dense
than liquid water, causing ice to float on water.
Figure 15. The
structure of ice.

10. Relate this property to the
survival of aquatic organisms in
temperate countries:
Water bodies freeze from the top down. If ice is not
able to float, the water bodies would freeze from top
to bottom, and aquatic life will be killed. Because ice
floats, aquatic organisms survive under the surface,
which remain liquid. The ice surface also acts as an
insulating layer protecting the water beneath from
further freezing, and maintains a temperature
adequate for survival. Without this feature, there
would be no aquatic life in temperate and Polar
Regions.

11. PROPERTIES OF WATER
 At sea level, pure water boils at 100 °C and freezes
at 0 °C.
 The boiling temperature of water decreases at higher
elevations (lower atmospheric pressure).
 For this reason, an egg will take longer to boil at
higher altitudes

12. PROPERTIES OF WATER
 At sea level, pure water boils at 100 °C and freezes
at 0 °C.
 The boiling temperature of water decreases at higher
elevations (lower atmospheric pressure).
 For this reason, an egg will take longer to boil at
higher altitudes

13. COHESION
 Attraction between particles of the
same substance ( why water is
attracted to itself)
•Results in Surface tension (a measure
of the strength of water’s surface)
 Produces a surface film on water that
allows insects to walk on the surface
of water

14. COHESION …
Helps insects walk across
water

15. ADHESION
• Attraction between two different
substances.
• Water will make hydrogen bonds with other
surfaces such as glass, soil, plant tissues,
and cotton.
 Capillary action-water molecules will “tow”
each other along when in a thin glass tube.
 Example: transpiration process which plants
and trees remove water from the soil, and
paper towels soak up water.

16. ADHESION CAUSES
CAPILLARY ACTION
Which gives water the
ability to “climb”
structures

17. ADHESION ALSO CAUSES
WATER TO …
Form spheres &
hold onto plant
leaves
Attach to a
silken spider
web

18. HIGH HEAT OF
VAPORIZATION
 Amount of energy to convert 1g or a substance from
a liquid to a gas
 In order for water to evaporate, hydrogen bonds
must be broken.
.As water evaporates, it removes a lot of heat with
it.
Effect: during summer we do not heat up and lose all of the water
in our body.

19. HIGH HEAT OF
VAPORIZATION
 Water's heat of vaporization is 540 cal/g.
 In order for water to evaporate, each gram must
GAIN 540 calories (temperature doesn’t change ---
100oC).
 As water evaporates, it removes a lot of heat with it
(cooling effect).

20. Water vapor forms a kind of
global ‘‘blanket” which helps to
keep the Earth warm.
Heat radiated from the sun
warmed surface of the earth is
absorbed and held
by the vapor.

21. WATER HAS HIGH HEAT OF
FUSION
 A lot of heat must be evolved to condense vapor into liquid
water and solidify water into ice.
 * Effect: organisms are protected against freezing
at lower temperature.

22. WATER HAS MAXIMUM DENSITY
AT 40C.
 At temperatures below 40C, water expands instead of contracting.
 Effects: ice floats in liquid water , important
in maintaining marine life because water
freezes from top to bottom

23. WATER IS LESS DENSE AS
A SOLID
• Ice is less dense as a solid than as a liquid (ice floats)
• Liquid water has hydrogen bonds that are constantly
being broken and reformed.
• Frozen water forms a crystal-like lattice whereby
molecules are set at fixed distances.

24. Water is Less Dense as a
Solid
•Which is ice and which is water?

25. Water is Less Dense as a
Solid
Water Ice

26. THANKYOU FOR
LISTENING!