9 . Soap powder and scouring soaps These contain a scouring agent ( abrasive ) such as powdered pumice or finely divided sand and builders like sodium carbonate and trisodium phosphate . Builders make the soaps act more quickly .
Disadvantages of Soaps
Soap is good cleansing agent and is 100 % biodegradable microorganisms present in sewage water can completely oxidise soap to CO2 , As a result , it does not create any pollution problem . However soaps have two disadvantages :
( i ) Soaps cannot be used in hard water since calcium magnesium ions present in hard water produce curdy precipitates of calcium and magnesium soaps .
These insoluble soaps separate as scum in water and causes hinderance to washing because the precipitate adheres onto the fibre of the cloth as gummy mass . Thus , a lot of soap is wasted if water . is hard .
( ii ) Soaps cannot be used in acidic solutions since acids precipitate the insoluble free fatty acids which adhere to the fabrics and thus , reduce the ability of soaps to remove oil and grease from fabrics .