Page 61 - ICSE Chemistry 6

Activity 3.10

Aim: To show that gases can be compressed easily whereas solids cannot be compressed and liquids can
be compressed a li le
Materials required: Three-20 mL syringes, 3 rubber cork, some water, some fl our or sand

Procedure
• Take three-20 mL syringes.
• Block their nozzles with rubber corks as shown in the fi gure.

• Remove the pistons from the syringes.
• Leave the fi rst syringe empty, fi ll water in the second syringe and wheat fl our or
sand in the third syringe.
• Insert the pistons back into the syringes.

• Try to compress the contents of the syringes by pushing the piston in each
syringe.
Observa on: The piston could be pushed easily in the fi rst syringe which was empty because it contained
air. The piston of the second syringe which contained water moved in a li le on applying the pressure. The
piston of the third syringe containing solid did not move in at all.

Conclusion: This shows that gases are highly compressible, liquids are only slightly compressible and
solids cannot be compressed at all.

Thirst for Knowledge

Some examples of compressed gases are listed below.
• LPG (Liquefi ed Petroleum Gas) that we use in our houses for cooking
• Oxygen supplied to hospitals, mountaineers and sea divers in cylinders
• CNG (Compressed Natural Gas) used as fuel in vehicles

Table 3.2: Dis nguishing Features of Solids, Liquids and Gases
Property Solids Liquids Gases

Intermolecular The molecules are closely The molecules are less closely The molecules are further
space packed. packed. apart.
Intermolecular The intermolecular force of The intermolecular force of The intermolecular force of
force of attraction attraction is very strong. attraction is not so strong. attraction is weak.

Shape Solids have deϐinite shape. Liquids do not have deϐinite Gases do not have deϐinite
shape. They take the shape of the shape. They ϐill the entire
container they are kept in. space available.
Volume Solids have deϐinite volume. Liquids have deϐinite volume. Gases do not have deϐinite
volume.
Fluidity Solids do not ϐlow. Liquids are free ϐlowing. Gases ϐlow in all directions.

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