Both soap 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 arise due to the use of detergents instead of soaps .

Explanation

`**" "`Soaps are the sodium salts or potassium salts of long chain carboxylic acids, while the detergents are the ammonium or sulphonate salts of long chain carboxylic acids.
`**" "`Mechanism of cleansing action of soaps. Soaps are molecules in which the two ends have differing properties, one is hydrophilic, that is, it dissolves in water, while the other end is hydrophobic, that is, it dissolves in hydrocarbons. When soap is at the surface of water, the hydrophobic 'tail' of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and the hydrocarbon 'tail' protruding out of water. Inside water, these molecules have a unique orientation that keeps the hydrocarbon portion out of the water. This is achieved by forming clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ands are on the surface of the cluster. this formation is called a micelle. Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the centre of the micelle.

The micelles stay in solution as a colloid and will not come together to precipitate because of ion-ion repulsion. Thus, the dirt suspended in the micelles is also easily rinsed away.
`**" "`With hard water soap molecules form insoluble salts `Ca^(2+)` or `Mg^(2+)` ions present in the hard water, So soaps do not form lather with hard water.
`**" "`Two problems of using detergents :
(i) Detergents are non-biodegradable and thus these cause pollution of water bodies.
(ii) Detergents are strong cleansing agents but these cause damage to the skins of the person using them.