Colloids

A colloid is a type of mixture that falls between a homogeneous mixture and a heterogeneous mixture. It consists of small particles distributed throughout a medium, neither settling out like in a suspension nor dissolving completely like in a solution.

Homogeneous mixtures, also known as solutions, have tiny dissolved particles distributed evenly throughout the medium. Examples include sugar dissolved in water. The solution appears uniform and the particles do not settle out.

In a heterogeneous mixture, the components are visibly separate, like sand and water. Stirring the mixture temporarily disperses the components, but they settle out over time.

Colloids fall between suspensions and solutions. They have particles larger than those in solutions that do not settle out like in suspensions. An example is fog, where tiny water droplets are dispersed in the air.

Colloids have dispersed substances and dispersion mediums. Examples include aerosols (dispersed solid or liquid in gas), foams (dispersed gas in liquid), and emulsions (immiscible liquids stabilized by emulsifiers like egg yolk).

Colloids exhibit the Tyndall effect, where they scatter light when it passes through them. This effect helps distinguish colloids from solutions. Colloids can show the Tyndall effect, unlike solutions where particles are too small to scatter light.