Soaps are salts of sodium or potassium of higher fatty acids. Whereas detergents are ammonium or sulphonate salts of long chain carboxylic acids.
Cleaning action of soap:
The cleaning action of soap is due to micelle formation and emulsion formation.Inside water a unique orientation forms clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends on the surface of cluster. This results in the formation of micelle.Soap in the form of micelle cleans the (dirt) oil as the oil will be collected at the centre of micelle.This property of soap makes it an emulsifier. The dirt suspended in micelles is easily rinsed away. This is known as cleaning action of soap.
Disadvantage of soap
When soap is mixed with hard water the calcium and magnesium salts displaces the salts of sodium and potassium present in the soap and forms scum which is not soluble. Hence soaps are not effective in hard water for washing clothes.
Demerits of detergents
(i)Detergents are not biodegradable.
(ii)As the detergents are non-biodegradable they cause environmental pollution like water and soil pollution.
