Question

Write any two differences between soap and detergent.

Answer 1

Hint : Soap and detergents are substances which have the ability to remove the dirt from the surface when they get dissolved in water. Soaps are sodium salt of fatty acids but detergent are the sodium and potassium salts of sulfonic acid of hydrocarbons.

Complete Step By Step Answer:
The two differences between soap and detergent are:

SOAP	DETERGENT
Soaps are the sodium salt of long fatty acids.	Detergents are the sodium and potassium salts of benzene sulphonic acid.
They form scum upon reaction with calcium and magnesium ions present in hard water.	2. They do not form insoluble precipitate with calcium and magnesium ions.

Chemical structure of detergents and soaps:
As detergents (also called surface-active agents), soaps and detergents must have specific chemical structures as their molecules should have a hydrophobic part that is water insoluble part, such as a fatty acid or a long chain carbon group for example fatty alcohols or alkylbenzene. The molecule should also have a hydrophilic group that means water soluble group, such as $- COONa$ , or a sulfo group, for example: $- OS{O_3}Na$ or $- S{O_3}Na$ (such as in fatty alcohol sulfate or alkylbenzene sulfonate), or a long ethylene oxide chain in nonionic synthetic detergents.
This hydrophilic part helps to make the molecule soluble in water. During the cleaning process, the hydrophobic part of the molecule attaches itself to the surface (which has to be clean), and the hydrophilic part attaches itself to the water.

Note :
The process of manufacturing of soap is called saponification. In this process, fats and oils are heated together and then mixed with a liquid alkali to produce soap and water in addition with glycerine. After that, Fats and oils are hydrolysed by applying a high-pressure steam to get crude fatty acids and glycerine. The fatty acids are then purified by a distillation process and neutralized with an alkali to produce soap.