Q. 15. Explain the mechanism of the cleaning action of soaps.
A soap is a sodium or potassium salt of long chain fatty acids. It has one polar hydrophilic end and one non-polar hydrophobic end.
When soap is at the surface of water, the hydrophobic tail of soap being non soluble in water protrudes out of water with the ionic end in water.
When there is no more space for soap molecules on the surface, these molecules create a unique orientation inside water in form of clusters in which hydrophobic ends are in the interior of the cluster and ionic ends on the surface of cluster thus keeping the hydrocarbon portion out of water. This formation is known as Micelle.
Soap in the form of a micelle is able to clean, as the oily dirt is collected in the centre of the micelle.The ionic ends in the micelles remain attached to water. When the dirty clothes are agitated in soap solution, the oily dirt particles entrapped by soap micelles get dispersed in water and the clothes get cleaned.