Question

What are colloidal solutions? Give one example of the following types of colloids:

(i) Liquid dispersed in gas.

(ii) Gas dispersed in liquid.

(iii) Liquid dispersed in solid.

(iv) Liquid dispersed in liquid.

(v) Solid dispersed in gas.

Answer 1

Colloidal solutions:

1. A colloidal solution is a solution in which the size of the solute particles is intermediate between those in true solutions and suspensions.
2. A colloid contains two components - dispersed phase and the dispersion medium
3. The dispersed phase is the compound which is present in small proportion and consists of particles of colloidal dimensions (${10}^{-9}\mathrm{m}\mathrm{to}{10}^{-7}\mathrm{m}.$)
4. A dispersion medium is a component which is present in excess and acts as a medium in which colloidal particles are dispersed.
5. Aerosol: It is a colloidal solution in which liquid/solid is the dispersed phase and gas is the dispersion medium.
6. Sol: It is a colloidal solution in which solid is the dispersed phase and liquid is the dispersion medium.
7. Gel: It is a colloidal solution in which liquid is the dispersed phase and solid is the dispersion medium.
8. Foam: It is a colloidal solution in which gas is the dispersed phase and liquid is the dispersion medium.

Examples of each type of colloids:

(i) Liquid dispersed in gas - mist, fog.

(ii) Gas dispersed in liquid - shaving cream, soda water.

(ii) Liquid dispersed in solid - jelly, cheese, butter.

(iv) Liquid dispersed in liquid - milk, , face cream.

(v) Solid dispersed in gas - smoke, dust, storm.