Brownian motion is the random movement of particles in a liquid or a gas caused due to collision with smaller, invisible particles
Evidence for Brownian Motion:
In liquid- Pollen grains in water
In gases- Smoke in air
Diffusion is is the spreading of one substance (liquid or gas) through another from a region of high concentration to a region of low concentration due to the continuousrandom motion of particles.
Evidence for diffusion:
In liquids: potassiummanganate (VII) in a beaker of water
In gases: a gas jar of air and a gas jar of bromine connected
Factors that affect the rate of diffusion:
Temperature increases → rate of diffusion increases
Lower relative molecular mass→ rate of diffusion is higher