1. DIFFUSION
Spray perfume into the room and ask them if they could smell it. Then ask, why they could smell it.

2. What is diffusion?

3. Diffusion is the random movement and mixing of particles.

4. Why do the particles move?

5. Because they have the energy to move
Because they have the energy to move. You do NOT need to move or stir to make the diffusion happen.

6. Watch the ANIMATION Watch the ANIMATION 2

7. How does the molecular mass affect the rate of diffusion for gases?
Click HERE to watch the VIDEO.
What end the ring is closer to? and Why?
Let them take notes here for the answers to the questions.

8. Why did the white ring form closer to the HCl end?
HCl and NH3 diffuse from opposite ends of tube.
Gases meet to form NH4Cl (the white ring)
HCl heavier than NH3
Therefore, NH4Cl forms closer to HCl end of tube.
NH4Cl, the white ring

9. How does the molecular mass affect the rate of diffusion of gases?
The lower the molecular mass of gas particles, the faster the gas will diffuse.