Soaps are sodium or potassium salts of long-chain fatty acids [carboxylic acids -Stearic acid, palmitic acid or oleic acid].
Saponification: The process in which oil or fat is hydrolyzed with Sodium hydroxide to get soap and glycerol is called saponification. The ionic-end of soap dissolves in water while the carbon chain dissolves in oil.
Types of Soap: Depending upon the nature of alkali used in the production of soap, they are classified into two types.
a) The sodium salt of long chain fatty acid is known as hard soap. It is difficult to dissolve in water. It is used as laundry soap.
b) The potassium salt of long chain fatty acid is known as soft soap, as it produces more lather. It is used as toilet soap and shaving soap.