Question

What is the chemical formula of detergent?

Answer 1

Hint: Detergents help in the cleaning process by the formation of micelles. They have two ends namely lyophilic and lyophobic. Lyophilic is the water loving end which attaches to water and lyophobic is the water repulsive or oil loving end.

Complete answer:
Detergents are chemically defined as \[ammonium{\text{ }}or{\text{ }}alkyl{\text{ }}benzene{\text{ }}sulfonate\] salts of a long chain of carboxylic acids. The chemical formula is \[{C_{18}}{H_{29}}Na{O_3}S\] . They have an incredible foaming ability and can be easily compounded with various other additives.
The reason why detergents are effective is because they are amphipathic. This means that they have dual affinity. They are both lyophilic as well as lyophobic in nature.
Cleaning action of detergents –
The cleaning action of both soaps and detergents are due to their ability to lower the surface tension of water, to emulsify oil or grease and to hold them in suspension in water. The hydrocarbon chain of detergents which is lyophobic is soluble in oil or grease whereas the lyophilic part is soluble in water. When detergents dissolve in water it forms anion and sodium cation. As the detergent reduces the surface tension the surface of the cloth is wetted thoroughly. When we scrub or during mechanical agitation the grease is pulled away from cloth. Finally rinsing washes away the droplets.
Soaps and detergents consist of a large hydrocarbon tail with a negatively charged head. Polar end is hydrophilic and the hydrocarbon tail is hydrophobic. In aqueous solution, water molecules being polar in nature, surround the ions and not the hydrocarbon part of the molecule. When a soap or detergent is dissolved in water, the molecules associate together as clusters called micelles.

Note:
Detergents when added to hard water, they form calcium and magnesium salts of detergents which are soluble in water and therefore can be used even with hard water. In case of soaps due to the presence of chlorides, sulphates and bicarbonates, water becomes hard and when sufficient amounts of soap is added they produce lather and stick to it, therefore soaps cannot be used with hard water.