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This topic focuses on a variety of colloidal systems and stresses their importance in everday life.

Colloids are a mixture, that are between true solutions and suspensions
e.g milk, with butterfat dispersed within.
Particles are larger than those in a solution, but smaller than those in a suspension

Name of Colloid	Componants	Examples
Aerosol	liquid dispered in a gas	mist, fog, clouds
Sol	solid particles suspended in a liquid	paints, toothpaste
Emulsion	droplets of insoluable liquid held together by an emulsifier	cream, milk
Foam	bubbles of gas trapped in a liquid	whipped cream, shaving foam
Gel	liquid trapped in a solid	jellies, custards, hair gel

Colloidal particles have an influence on visible light
their particles are just the right size to cause light to be scattered at large angles.
This is known as the Tyndal Effect

Emulsifiers

prevents two substances in a colloid from sticking to each other
- e.g mayonnaise. oil + viniger (water), oil and water do not mix
- egg yolk is the emulsifier
emulsifiers are made up of long molecules
they have a head and tail. the head is attracted to water, and tail is attracted to the insoluable substance
this prevents oil and water molecules coming into contact, and clumping together

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by: Admin
Total views: 1938
Word Count: 553
Date: Sun, 21 May 2006 Time: 12:00 AM
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