What is a 'soap' ? How is it prepared ?

Explanation

Soaps : Soaps are generally mixtures of sodium and potassium salt of higher fatty acids such as stearic, palmitic and oleic acids. For effective cleansing action of soap, its fatty acid unit must contains 12 to 18 carbon atoms. Soaps with less than 12 carbaon fatty acids are comparatively soluble in water whereas soaps containing more than 22 carbon atoms are not useful because of their insolubility in water.
Sodium soaps are hard whereas potassium soaps are soft,
Preparation : Shaving creams, shampoos etc., are mostly potassium soaps.
Soaps are usually obtained by the hydrolysis of oils and fats with sodium or potassium hydroxide.

Transparant soaps are prepared by dissolving ordinary soaps in alcohol and then removing the insoluble part by filtration. The solid transparent mass is obtained on evaporating off alcohol.