Answer to Question #269638 in Physical Chemistry for Faru

Question

Give a short account of colloidal state of matter with special reference to 5

classification, properties of colloids and preparation of colloids.

Answer 1

In chemistry, colloids are heterogeneous mixtures of two substances in which minute particles of one substance are dispersed in another substance. The substance whose minute particles are suspended in another substance is called the dispersed phase while the substance in which it is suspended is called dispersion medium. For example, in fog dispersed phase is water (liquid) and dispersion medium is different gases. We can’t see particles of dispersed phase in colloids by naked eyes as they are very small in size. 

Examples of Colloids 

We see many colloidal solutions around us. Many food items such as cake, milk, bread, butter, ice cream fruit juices, whipped cream etc. are examples of colloids. Apart from these fog, mist clay etc. are also examples of colloids.

Properties of Colloids 

Colloids show following properties –

• It is a heterogenous mixture. 
• The size of colloidal particles is very small. Their particle size ranges between 1-1000 nanometers. 
• It shows tyndall effect. It means it scatters the beam of light and shows its path through itself. 
• They don’t settle down when left undisturbed for sometime it means colloidal solutions are quite stable. 
• They cannot be separated by filtration process. 
• They can be separated by centrifugation. 
• Colloidal particles show Brownian movement.