Brownian Motion and Diffusion

• 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 continuous random motion of particles.
• Evidence for diffusion:

  • In liquids: potassium manganate (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