Question

Amphiphilic molecules are normally associated with [Orissa JEE $1997$]
A.Isoprene based polymer
B.Soaps and detergents
C.Nitrogen based fertilizers
D.Pain relieving medicines such as aspirin

Answer 1

Hint: Amphiphilic molecules are those chemical compounds that contain both lipophilic and hydrophilic properties. Lipophilic means lipid-loving or fat-loving chemical species and hydrophilic means water-loving chemical species. Hence amphiphilic molecules are associated with those substances containing both lipophilic and hydrophilic properties.

Complete answer:Amphiphilic consists of two greek words ‘’Amphis’’ means both and ‘’philia’’ means love that is the chemical compounds that have both the region of polar and nonpolar giving them both hydrophilic and lipophilic properties are called amphiphilic molecules.

In amphiphilic compounds, one part possesses a strong affinity for polar molecules to lie in the water and another part possesses a high affinity for non-polar solvents such as hydrocarbons, esters, ethers, etc. These molecules have very good surfactant properties which means they lower the surface tension of water and thereby allowing it to penetrate and wet a variety of materials.

In an aqueous solution, these molecules form micelles. The hydrophilic part forms the outer surface of the micelle and is exposed to water whereas a hydrophilic portion of the molecule is shielded from water. Soaps and detergents contain amphiphilic molecules which make them strong surfactants and thereby can be used as cleaning agents.
Therefore amphiphilic molecules are normally associated with soaps and detergents.

Thus, option (B) is correct.

Note: Generally soaps are sodium or potassium salts of carboxylic acid consisting of a long aliphatic chain but detergents are sodium or potassium salts of a long alkyl chain ending with a sulfonate group. Detergents are soluble in hard water but soaps are not soluble in hard water.