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Science PT3 Chapter 5 Water and Solution

5.1 Physical Characteristics of Water

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1. Pure water has several physical characteristics as follow:
(a) Tasteless, odourless and colourless
(b) Boiling point is 100 C and freezing point or melting point is 0 C
o
o
(c) Has high surface tension
(d) Density is 1 g cm -3
(e) Low electrical conductivity

Adhesive
force
Cohesive
force INFO CORNER
Cohesive force:
Insects are able to stay Capillary action is a phenomenon that Attractive force between
afloat on water due to enables water to be carried from similar molecules
high surface tension. the roots to the leaves through the Adhesive force:
The surface tension is action of cohesive force between the
the result of cohesive molecules and adhesive force among Attractive force between
force between the water the water molecules and xylem wall. different molecules
molecules.
Diagram 5.1
2. The absorption and release of heat to the surrounding cause the change of state
of water.
Sublimation

Evaporation/ Form 2
Melting Boiling
Form 2
Freezing Condensation Gas
Solid Liquid
Heat is absorbed
Sublimation Heat is released
Diagram 5.2 Effect of absorption and release of heat

Composition of Water
1. Water is a compound. One molecule of water is made up
of one oxygen atom and two hydrogen atoms.
O
1 molecule water = 2 hydrogen atoms + 1 oxygen atom
H H
2. The components of water can only be separated through
a chemical process known as electrolysis. Diagram 5.3 Structure
3. The composition of the elements in the water molecule of water
can be ascertained by carrying out the electrolysis process as follow.

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