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Action of soap is due to emulsification and micelle formation. Comment.

5.18         Action of soap is due to emulsification and micelle formation. Comment.

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M manish

The cleansing action of soap is because of emulsification and micelle formation. Soaps are sodium or potassium salts of long chain fatty acids, represented as RCOO^{-}Na^{+} (e.g. sodium stearate CH_{3}(CH_{2})_{16}COO^{-}Na^{+}). when dissolved into the water it dissociates into RCOO^{-} and Na^{+} ions. (RCOO^{-}Na^{+}\rightleftharpoons RCOO^{-}+Na^{+}). The long carbon chains are non-polar in nature (hydrophobic) and COO^{-} are polar in nature (hydrophilic part).

When the soap is added to dirt containing water. The soap molecules surround the dirt particle where the hydrophobic part is attached to dirt and the hydrophilic part is pointing away from the dirt. This is called micelle formation. Therefore we can say that the non-polar part dissolved in dirt particle and the polar group dissolved in water. Now, as these micelles are negatively charged, they do not coalesce and a stable emulsion is formed.

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