1. 1
STATES OF MATTER

2. EXPANSION and CONTRACTION of LIQUIDS and GASES2
EXPANSION and CONTRACTION of LIQUIDS and GASES

3. 3
Learning Points
State that matter expands when it is heated and contracts when cooled.
Explain the expansion and contraction of solids, liquids and gases in terms of particle theory.
Describe applications of expansion of solids, liquids and gases.

4. Expansion & contraction of liquids4
Expansion & contraction of liquids
Mercury and alcohol are liquids that expand and contract in thermometers.

5. EXPERIMENT AIM: To find out what happens to liquids5
EXPERIMENT
AIM: To find out what happens to liquids
when they are heated and cooled.

6. 6
INSTRUCTIONS
Fill two test-tubes to near the top with the red coloured water provided.
Place the tops on the test-tubes and secure them using a clamp-stand.

7. 7
3. Lower the test-tubes into a beaker containing either hot or cold water.
4. Watch what happens to the level of the red water in each test-tube over the next 5 minutes.

8. 8
WHAT DID YOU FIND OUT?

9. SOME QUESTIONS? Q. Can you explain why liquids expand when they9
SOME QUESTIONS?
Q. Can you explain why liquids expand when they
are heated and contract when they are cooled?
Q. What happens to how the particles in the
red liquid are arranged when they are heated
and then cooled?

10. 1010
EXPLANATION
The particles in liquids are a little further apart to each other than is the case in a solid.
When a liquid is heated the distance between its particles become larger and it expands.
When the liquid is cooled it contracts and its the particles move back close to each other.

11. Expansion & contraction of gases
1111
Expansion & contraction of gases
Air expands when heated (becoming less dense) so it floats
This is how hot air balloons work.

12. EXPERIMENT AIM: To find out what happens to gases
1212
EXPERIMENT
AIM: To find out what happens to gases
when they are heated and cooled.

13. INSTRUCTIONS 1. Draw out the following table. TEST-TUBE
1313
INSTRUCTIONS
1. Draw out the following table.
TEST-TUBE
NUMBER OF AIR BUBBLES
LEAVING FOR 5 MINUTES BEFORE HEATING
DURING HEATING FOR
5 MINUTES
LEAVING FOR 5 MINUTES AFTER HEATING

14. 1414
INSTRUCTIONS
2. Collect a test-tube with a glass tube sticking out of it.
3. Place the test-tube upside down with the glass tube sticking into the water and secure them using a clamp- stand.

15. 1515
INSTRUCTIONS
4. Count the number of bubbles of air coming out of the bottom of the glass tube for 5 minutes.
5. Write down the number of bubbles produced in the table.

16. 1616
INSTRUCTIONS
6. Carefully warm up the test-tube with your hands for 5 minutes.
7. Write down the number of bubbles produced in the table.

17. 1717
INSTRUCTIONS
8. Take your hands away and allow the test-tube to cool for 5 minutes.
9. Write down the number of bubbles produced in the table during this cooling down period.

18. 1818
WHAT DID YOU FIND OUT?

19. WHAT DID YOU FIND OUT? The heat from the hands made the air in the
1919
WHAT DID YOU FIND OUT?
The heat from the hands made the air in the
test tube heat up and expand. The expanded
air pushed out of the test-tube and into the
water as bubbles.
When the hot hands were taken away, the air
in the test tube became cooler and the air
began to cool.
The space in the test-tube taken up by the air
that escaped during heating was replaced by
water moving into the test-tube.

20. 2020
EXPLANATION
The particles in gases are further apart to each other than is the case in a solid or liquid and are easier to expand.
When a gas is heated the distance between its particles become larger and it expands.
When the gas is cooled it contracts and its the particles move back to their starting positions.