A soap molecule consists of two parts - one part is long chain of hydrocarbon and the other part is of –COONa group. Hydrocarbons are hydrophobic. The scum

sticks to the hydrocarbon part of the soap molecule. The –COONa part sticks to the water and removes the dirt from the surface of the cloth. This cleanses the cloth.

When soap is dissolved in water, it forms micelles, in which the soap molecules are arranged in a cluster form. The hydrocarbon part of the soap towards the center and the hydrophilic part faces outward. These micelles are formed around the particles of scum present on the surface of the soap-soaked cloth.