- the net movement of particles from an area of higher concentration to an area of lower concentration.
- it can happen in both liquids and gases
- this is because the individual particles are free to move about randomly
- Rate of diffusion depends on 3 things
- distance- substances diffuse more quickly when they don't have as far to move
- concentration difference- substances diffuse faster if if there's a big difference in concentration
- if there are more particles on one side there are more to move across
- surface area- the more surface area available for molecules to move across the faster they can get from one side to the other