Colloids

Colloids are mixtures in which microscopic particles of one substance are dispersed throughout another substance but remain suspended rather than dissolving.

Common examples:

• Milk (fat droplets in water)
• Fog (water droplets in air)
• Mayonnaise (oil droplets in water)
• Paint (solid pigments in liquid)

Unlike solutions, colloidal particles are large enough to scatter light (Tyndall effect) but small enough to remain suspended.

Related: Stokes’ Law