Surfactants have a molecular structure that acts as a link between water and the dirt particles, loosening the particles from the underlying fibers or other surfaces to be cleaned. The hydrophilic end is similar in structure to water-soluble salts. The hydrophobic part of the molecule frequently consists of a hydrocarbon chain that is similar to the structure of grease, oil, and many fats. Soap powder is a hydrated mixture of soap and sodium carbonate. Powdered soap, which is used in dispensers, is a dry soap that has been pulverized to a fine powder.
Liquid soap is a solution of soft potassium soap dissolved in water.
In the late 1960s, because of the increasing concern over the pollution of water resources, the inclusion of harmful chemicals, such as phosphates, in soaps and detergents was actively discouraged. Instead, biodegradable agents that are easily broken down and digested by bacteria came into wide use.