NCERT Solution for Class Tenth Science Chapter 4
Carbon and its Compounds
CBSE NCERT Book Session-2022-2023
Intext Questions
Page No-21
Questions No-15
Explain the mechanism of the cleaning action of soaps.
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NCERT Solution for Class Tenth Science Chapter 4
Carbon and its Compounds
CBSE NCERT Book Session-2022-2023
Intext Questions
Page No-21
Questions No-15
The dirt present on clothes is oily in nature and 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. When flushed with excess water, the dust particles are easily rinsed away by water.
The cleaning action of soaps is based on their unique ability to act as surfactants (surface-active agents). Soaps are molecules that have a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. This structure allows them to interact with both water and oils or grease, making them effective for cleaning. The mechanism of soap’s cleaning action involves several key steps:
1. Emulsification:
When you apply soap to a surface that is dirty with oils, grease, or other hydrophobic substances, the hydrophobic tails of the soap molecules are attracted to the dirt particles, while the hydrophilic heads are oriented towards the water. Soap molecules surround the oil or grease droplets, forming structures called micelles. In these micelles, the hydrophobic tails cluster in the interior, isolating the dirt from the surrounding water.
2 Dispersion:
The soap molecules disperse the dirt or grease into tiny droplets within the micelles. These tiny droplets are suspended in the water, effectively breaking down the larger, hydrophobic dirt particles into smaller, more manageable ones.
3. Removal:
Once the dirt or grease is emulsified and dispersed into the water, it can be easily rinsed away with water. The hydrophilic heads of the soap molecules ensure that the micelles remain suspended in the water, preventing the dirt particles from reattaching to the surface being cleaned.
4. Saponification:
In some cases, especially when dealing with alkali metals like sodium and potassium, soap can react with fatty acids to form soap salts. This reaction is known as saponification. The resulting soap salts are water-soluble and can be easily rinsed away, taking the dirt with them.
Soaps are particularly effective for cleaning because they allow the removal of oils and grease from surfaces that water alone might not be able to clean. The hydrophilic heads of the soap molecules help these substances mix with water, enabling the effective removal of dirt and grease from various surfaces, including skin, clothing, dishes, and more. This emulsification and dispersion of dirt and oils are key to the cleaning action of soaps.