Colloids - Definition, Types and Formation of Colloids

Particles are of a colloidal size if their size falls in the range of 1 to 1000nm.

A colloid is system whereby colloidal particles are suspended in a continuous medium. They are stable and do not settle. The action of the medium (such as water) is sufficient to keep the particles in suspension and they do not settle out under as a result of gravity.

A colloid is a type of suspension, however, it differs from a solution. In a colloid the particles are insoluble. Solutions contained dissolved species, that are typically of molecular size and smaller than colloids. Colloids also tend to scatter light, whereas it is quite rare for a solution to scatter light.

Colloids are classified by the dispersed materials and the continuous phase.

Dispersed Material

Continuous Phase

Example

Gas

Liquid

Shaving foam

Gas

Solid

Styrofoam

Liquid

Gas

Fog

Liquid

Liquid

Homogenized milk

Liquid

Solid

Cheese

Solid

Gas

Smoke

Solid

Liquid

Ink/Paint

Solid

Solid

Some alloys

Colloids can be formed by the reduction in size of larger particles or the condensation of molecules into colloidal particles

 

Source: AZoM.com

 

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