Soaps used for cleaning purposes are sodium or potassium salts of long-chain fatty acids , e.g. stearic, oleic, and palmitic acids . Hence, Statement1 is correct. Soaps containing sodium salts are formed by heating fat (i.e. glyceryl ester of fatty acid ) with an aqueous sodium hydroxide solution . This reaction is known as saponification . In this reaction, esters of fatty acids are hydrolyzed 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 soft to the skin than sodium soaps . These can be prepared by using a potassium hydroxide solution in place of sodium hydroxide . Hard water contains calcium and magnesium ions. Hence, Statement 2 is incorrect. These ions form insoluble calcium and magnesium soaps respectively when sodium or potassium soaps are dissolved in hard water . These insoluble soaps separate as scum in water and are useless as a cleansing agent. In fact, these are a hindrance to good washing , because they precipitate adheres onto the fibre of the cloth as gummy mass. Hair washed with hard water looks dull because of this sticky precipitate . Dye does not absorb evenly on cloth washed with soap using hard water, because of this gummy mass .
