Describe in brief the cleansing action of soap. - Science

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Answer in Brief

Describe in brief the cleansing action of soap.

Explain the cleansing action of soaps.

Explain the mechanism of the cleaning action of soaps.

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Solution 1

Cleansing action of soaps:

The dirt present on clothes is organic in nature and is insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remain suspended in the water and, thus, the dust particles are easily rinsed away by water.

Solution 2

The cleaning action of soap can be described as follows:

  • A soap molecule has a tadpole-shaped structure.
  • At one end (long, non-polar end) of the soap molecule is a hydrocarbon chain which is insoluble in water but soluble in oil.
  • At the other end (short polar end) of the soap molecule, there is a carboxylate ion which is hydrophilic, i.e. water soluble but insoluble in oil.

  • Soap, on mixed with water, forms a concentrated solution and causes foaming.
  • The long non-polar end of soap gravitates towards and surrounds the dirt and absorbs the dust in it.
  • The short polar end with the carboxylate ion repels the water away from the dirt.
  • A spherical aggregate of soap molecules is formed in the soap solution in water and is called a micelle.
  • Thus, the soap molecule dissolves the dirt and our clothes get clean.


            Formation of micelles

Concept: Soap
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Chapter 4: Carbon and its Compounds - Exercises [Page 78]

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