Explain about soaps in detail.

(A) Soaps are detergents that have been used for a long time. Soaps used for cleaning purposes are sodium or potassium salts of long-chain fatty acids,such as stearic,oleic,and palmitic acids.
Soaps containing sodium: Soaps containing sodium salts are formed by heating fat with an aqueous sodium hydroxide solution. This reaction is known as saponification.
Chemical reaction of soap making:
$(CH_2-O-CO-C_{17}H_{35})-(CH-O-CO-C_{17}H_{35})-(CH_2-O-CO-C_{17}H_{35}) + 3NaOH$ $\rightarrow CH_2(OH)-CH(OH)-CH_2(OH) + 3C_{17}H_{35}COONa$
In this reaction,esters of fatty acids are hydrolysed,and the soap obtained remains in colloidal form. It is precipitated from the solution by adding sodium chloride.
The solution left after removing the soap contains glycerol,which can be recovered by fractional distillation. Only sodium and potassium soaps are soluble in water and are used for cleaning purposes. Generally,potassium soaps are softer to the skin than sodium soaps. These can be prepared by using potassium hydroxide solution in place of sodium hydroxide.
Basically,all soaps are made by boiling fats or oils with a suitable soluble hydroxide. Variations are made by using different raw materials.
$i$. Toilet soaps:
These are prepared by using better grades of fats and oils,and care is taken to remove excess alkali. Colour and perfumes are added to make these more attractive.