Question

Explain the mechanism of the cleaning action of soap.

Answer 1

The molecules of soap are sodium or potassium salts of long chain carboxylic acids.A soap molecule has a tadpole-shaped structure.At one end (long non-polar end) of the soap molecule is a hydrocarbon chain insoluble in water but soluble in oil.At the other end (short polar end) of the soap molecule, there is a carboxylate ion, which is hydrophilic, i.e. water soluble but insoluble in oil.Soap on mixing with water forms a concentrated solution and causes foaming.The long non-polar end of soap gravitates towards and surrounds the dirt and absorbs the dust in it.The short polar end with the carboxylate ion turns the water away from the dirt.A spherical aggregate of soap molecules is formed in the soap solution in water and is called a micelle.The soap molecule thus helps in dissolving the dirt in water and we can wash our clothes clean.

Answer 2

a soap molecule has a hydrophobic tail which is a carbon chain and a hydrophilic head which is an ionic end. when mixed with water, a group of molecules arrange themselves in such a shape that the tails are inside the cluster protected from water and the heads are on the outside. (due to this tails won't come in contact with water.) this structure is called a micelle. a micelle forms around a dirt or oil particle. when the mixture is agitated the micelles dislodge the particles and wash them away and thus the surface. is cleaned.