Write a note on surfactant (Surface active agent).

Que.: Write a note on surfactant (Surface active agent).

Ans.:

Surfactant:

Molecules and ions that are adsorbed at the interface are termed as surfactants, surface active agent or amphiphiles. Thus the molecules or ions have a certain affinity for both polar and non-polar solvent. These compounds have structure that contain 2 separate regions, a hydrophilic region which confers on the compound solubility in water and a hydrophobic or lipophilic region in which renders material soluble in hydrocarbon.

The lipophilic region is expelled from water phases but hydrophilic region prevents the surface active agent to be completely expelled from water phase.
Because of this dual structure it is energetically favourable for these materials, when dissolved, to adsorb at the interface orienting themselves in such a manner that the regions are with appropriate solvents.

The addition of a surfactant to water results in their orientation at the surface which also subsequently causes a decrease in the surface tension of water. Hence they are also called as surface active agents.
Thus all surfactants are characterized by having 2 regions in their molecular structure:
1. A lyophobic (hydrophobic/lipophilic)region such as hydrocarbon chain with has no affinity for aqueous solvent.
(ii) A lyophilic (hydrophilic) region that has affinity for water.

Que.: Write a note on surfactant (Surface active agent).