1. STATES OF MATTER

2. DIFFUSION

3. Learning Points
Explain diffusion in terms of particle theory.

4. Diffusion
If you open a bottle of perfume at arm's length you can soon smell it.
Perfume particles mingle with air particles and move through the air until they reach your nose. We call this diffusion.
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5. Diffusion
Diffusion is the movement of particles from a High concentration (level) to a low concentration.
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6. DIFFUSION OF GASES
When the particles of two gases mix, they spread easily through each other.
This is also called Diffusion.
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7. QUICK EXPERIMENT AIM: To find out if gases diffuse (move)
through the air.

8. INSTRUCTIONS Collect a stop-watch and set it to zero time.
Close your eyes and start the watch when your teacher has said that they have sprayed a substance into the classroom.
Stop the watch when you smell the substance.
Compare how long it took you to smell the gas substance.

9. WHAT HAPPENED?
CAN YOU EXPLAIN WHY?

10. EXPLANATION
Pupils closest to the sprayed gas smell it more quickly than those further away, because it is more concentrated.
Different gases diffuse (move) through the air at different speeds.

11. Your teacher is going to show you a brown coloured gas diffusing.
DIFFUSION OF GASES
Your teacher is going to show you a brown coloured gas diffusing.

12. Nitrogen dioxide diffusing
DIFFUSION OF GASES
Nitrogen dioxide diffusing
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13. DIFFUSION OF GASES Q. Do you think it would make any
difference if the glass jars were
turned sideways or upside down?

14. WHY DO GASES DIFFUSE? Gas particles move from an area where there is a
HIGH level to an area
where there is a low
LEVEL of the particles i.e.
DIFFUSION.

15. Click here to see a video on the
DIFFUSION OF GASES
Click here to see a video on the
diffusion of gases.

16. GASES DIFFUSING IN YOUR BODY diffusing all the time to
In your lungs gases
(oxygen and carbon
dioxide) are
diffusing all the time to
keep you alive.
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17. GASES DIFFUSING IN YOUR BODY diffusing all the time to
In your lungs gases
(oxygen and carbon
dioxide) are
diffusing all the time to
keep you alive.
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