Diffusion
Science: KS3, topic 3.5.9
Diffusion
Diffusion can happen in liquids and gases. Diffusion is the movement of particles as they spread out from a higher concentration to a lower concentration.
Concentration
- If there is a high concentration of particles, there are many particles in a given volume.
Diffusion
- Diffusion is the net movement of particles from a high concentration to a lower concentration.
- Diffusion can only happen in gases and liquids as the particles need to be able to move.
- Particles in a solid are unable to move - they only vibrate.
- The rate of diffusion will increase:
- At higher temperatures.
- With a larger concentration gradient.
Diffusion in gases
- Have you wondered why you can smell deodorant if a person sprays it in another room or how you smell your dinner cooking if you are upstairs?
- The smell travels as its particles are at a higher concentration than the rest of the room.
- These particles mix with the rest in the room and start to spread.
- Eventually they will spread out evenly, but continue to move.
Diffusion in liquids
- Diffusion can happen in liquids as particles are able to move.
- If you spill ink in water, the higher concentration of ink will spread out in the water, changing the water's colour.
Test yourself on Diffusion
Choose the correct statement about diffusion
What state will diffusion NOT occur in?
A teacher opens a bottle of ammonia at the front of a classroom. It takes several seconds before students at the back can smell it. Why does this happen?