These are liquid-liquid colloidal systems. If a mixture of two immiscible or partially miscible liquids is shaken, an emulsion is obtained. These are generally stabilized by adding certain substances like protein, gum, soap, alcohol, etc called the emulsifying agents or emulsifiers.
Types of Emulsions
Emulsions are of two types; oil dispersed in water (o/w type) and water dispersed in oil (w/o type). Milk and vanishing cream are the examples of o/w type emulsions. In the milk, liquid fat is dispersed in water. Butter and cream are the examples of w/o type emulsions.
Properties of Emulsions
- It is a dispersion of finely divided droplets into another liquid.
- Emulsions also show Brownian movement and Tyndall effect.
- These can be broken down into constituent liquids by heating, freezing centrifuging, etc.
Suspension
A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended through the bulk of the medium. Chalk water, the pulluted water of the river, smoke in atmospheric air, muddy water, etc are the examples of suspension.
Properties of a Suspension
- It is heterogeneous mixture
- The particles of a suspension can be seen by naked eye. Their size is of the order of 10-5 cm or more.
- The particles of a suspension scatter a beam of light passing through it and make its path visible.
- The solute particles settle down when a suspension is left undisturbed, i.e., suspension is unstable. They can be separated from the mixture by the process of filteration. When the particles settle down, the suspension breaks and it does not scatter light anymore.