What is the difference between the molecules of soaps and detergents, chemically ? Explain the deansing action of soaps.

Explanation

Detergents are sodium salt of long chain benzene sulphonic acids.
Soaps are sodium or potassium salt of long chain fatty acids that have cleaning action in water. e.g., Sodium stearate.
Cleansing Addion of Soap. A soap molecule consists of two dimilar parts :
(i) A short ionic part comprising the carboxylate salt--`COO^(-)Na^(+)` which is water soluble.
(ii) A long hydrocarbon chain which is hydrophobic.
When soap is dissolved in water, it forms a colloidal suspension. In this colloidal suspension, the soap molecules duster together to form micelles and remain radially suspended in water with the hydrocarbon end towards the centre and the ionic end directed outward. The dirt particles always adhere to the oily or greasy layer present on the skin or clothes. When a dirty cloth is dipped into a soap solution, its non-polar hydrocarbon end of micelles gets attached to the grease or oil present in dirt and polar end remains in water layer.
The mechanical action of rubbing subsequently, dislodges the oily layer from the dirty surface shaping it into small globules. A stable emulsion of oil in water is formed. The emulsified oil or grease globules bearing the dirt can now! eadily washed with water.