both soaps and detergent are some type of salts. what is the difference between them ?describe in brief the cleansing action of soap .why do soaps not form lather in hard water? list two problems that arises due to the use of detergent instead of soaps
Answers
Difference between them
Characteristics of Soaps:
Soaps used for cleaning purpose are sodium or potassium salts of long chain fatty acids.
They cannot be used in hard water or acidic solution as they precipitate out.
They are biodegradable and hence they do not cause water pollution.
e.g., stearic, oleic and palmitic acids.
Characteristics of Detergents:
Detergents are sodium salts of long chain alkyl sulphates or a long chain of alkyl benzene sulphonate.
They can be used in hard water and acidic medium.
They are not biodegradable. Hence they cause water pollution.
e.g. Sodium n-dodecyl benzene sulphonate, Cetyltrimethylammonium bromide, Pentaerythrityl stearate.
cleansing action of soap
Hydrophobic or water repelling non-polar part [usually a long hydrocarbon chain} is soluble in oil and greases but insoluble in water.
Hydrophilic or water attracting polar parts such as carboxylic group or sulphonate or sulphate is soluble in water and insoluble in oil and greases.
Molecules of soap form micelles in water. The hydrophobic part of soap dissolves in oil and grease while hydrophilic part of soap remains as free in soap solution. When the cloth is rubbed with hand or stirred mechanically, the big molecules of oil and soap break into small e mulsified o|l droplets.
These oil droplets repel each other due to the presence of anions of the hydrophilic part and do not precipitate. Thus they remain suspended in the soap solution without getting back on the cloth. These suspended oil and grease particles are then washed away by a stream of water.
If we use of detergent instead of soaps
with detergent, bacteria can't degrade easily so water pollution problem.
limited because of less branching priority.