Page 60 - ICSE Chemistry 6
P. 60
Activity 3.9
Aim: To observe that liquids have a defi nite volume but no fi xed shape
Materials required: A measuring cylinder, a cup, a glass bowl, some water
Procedure
• Take 100 mL water using a measuring cylinder.
• Pour the water in a glass and observe its shape.
• Then transfer this water to a cup. Observe its
shape. water in a glass water in a cup water in a bowl
• Finally, pour water from the cup to a bowl. Again observe its shape.
• Measure the volume of water using a measuring cylinder.
Observa on: You will observe that when water is poured in a glass, it takes the shape of the glass. When
it is poured in a cup, it takes the shape of the cup and when it is poured in a bowl, it takes the shape of
the bowl.
Conclusion: This shows that liquids do not have a defi nite shape. When the volume of water is measured
using a measuring cylinder, it is found to be the same, i.e., 100 mL. This shows that liquids have a defi nite
volume but no fi xed shape.
Gases
• Gases neither have a defi nite shape nor a defi nite volume. You
must have observed that when you pump air in a bicycle tyre
or a football, air takes the shape of the tyre or football. Oxygen,
carbon dioxide, nitrogen, sulphur dioxide, nitrogen oxide, etc.
are all gases.
Fig. 3.4: Arrangement of molecules
• Gases have maximum capacity to fl ow (fl uidity). In gases,
in gases
molecules are loosely packed. The intermolecular space
between the molecules is very large since intermolecular forces are weak. As a result, the
molecules arrange themselves in a manner to allow movement in all direc ons. They move around
independent of each other in the en re space available to them.
• Gases are highly compressible. They can be compressed easily (as compared to solids and liquids)
as their molecules are loosely packed.
• Gases have very low density. This is because the intermolecular space between the molecules in
gases is very large.
• Gases diff use very rapidly. The par cles in gases move rapidly
Thirst for Knowledge
in all direc ons. This results in the diff usion of par cles in a
gas into the space between the par cles of another gas. For Liquids and gases are fl uid
example, the fragrance of perfume when it is sprayed in one because they can fl ow and their
part of a room spreads in the en re room. shape is not fi xed.
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