Types of diffusion
Diffusion occurs in various states of matter.
Gas in gas/vacuum diffusion:
A gas released in a container diffuses and fills the container.
Liquid in liquid diffusion:
When two liquids that are miscible (i.e. they can be mixed) are introduced into a container and left untouched, diffusion occurs until the mixture is uniform.
Solid in liquid diffusion:
The particles of a solid that dissolve in a liquid similarly spread throughout the volume of the liquid.