These are substances, which have the competence to clean an object. It can be soapy or soapless detergents.
Soapy detergents – These are sodium or potassium salts of fatty acids. They are good cleansing agents in soft water but forms scum in hard water.
NB– Since soap is biodegradable, it causes no pollution. It forms scum’s because calcium salts of alkanoates are insoluble in water and hence the scum’s.
Soapless detergents – They are the sodium salts of sulphonic acid. They are the alkyl benzene sulphonates.
NB – They do not form scums in hard water because their calcium salts are soluble in water.
They are non-biodegradable and so can pollute the environment.