Diffusion
1. Definition:
Diffusion is the random movement and mixing of particles.
2. Why do these Particles move?
because they have energy
3. What does speed of mixing by diffusion depend on?
1. temperature
2. size and mass of the particles
3. the states of the substances that are diffusing.
4. Which particles diffuse more: particles from cold food or warm food?
Particles from warm food diffuse more quickly than those from cool food
because the warmer particles have more energy and move faster.
5. Size and mass of the particles:
bigger, heavier particles diffuse more slowly than smaller, lighter particles.
6. What state diffusion occurs more quickly?
Diffusion occurs quickly in gases, more slowly in liquids, and very slowly in solids.
7. Why does diffusion happen quickly in gases?
This is because a particle can travel a long distance before it hits another
particle.
8. Why does Diffusion happen more slowly in liquids than in gases?
This is because particles are closer in liquids, and there are stronger forces
between them.
9. Why Diffusion happens very slowly in solids?
This is because very strong Forces hold the particles in position.
10. What kind of diffusion happens in solar cells?
diffusion occurs in solids in this case, where phosphorus particles diffuse into silicon
at a high temperature.
11. Evidence for moving particles:
1. What did Robert Brown observe when he looked at the suspended
pollen grains in water through a microscope?
Robert Brown observed the suspended pollen grains moving around quickly in
water.
2. Why did the pollen grains move around quickly?
they were pushed around by the random movements of the water particles
around them.
3. How do the water particles push around the pollen grains despite being
much smaller?
This is because they are moving at high speeds.
The average speed of a water particle at 20°C is 1600 km/h.