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CHEMISTRY CBSE CLASS X

Soaps and Detergents

Detergent – Any substance which has cleansing action in water.
Two types - Soapy and Non soapy ( detergents)

Soaps

Sodium or potassium salt of a long chain carboxylic acid( fatty acid) which has cleansing properties in water. It has a large non-ionic hydrocarbon group and an ionic group  , COONa.

Eg.

Sodium Stearate – C₁₇H₃₅COONa

Sodium Palmitate  – C₁₅H₃₁COONa

• Soap is the salt of a strong base ( sodium hydroxide) and a weak acid
  So a solution of soap in water is basic in nature.

Manufacture of soap

Soap is made from animal fat or vegetable oils which when heated with sodium hydroxide solution ( caustic soda solution) , split to form sodium salt of higher fatty acid ( soap) and glycerol.

Saponification

The process of making soap by the hydrolysis of fats and oils with alkalis .

• Common salt is added in soap making ---  It is added to the mixture to make the soap come out of the solution. It precipitates out all the soap from the aqueous solution.
  
  
• The soap which is used for washing clothes or bathing works by making the oil and grease particles dissolve in water because the oil and grease are insoluble in water.

Structure of a Soap Molecule

A soap molecule is made up of 2 parts :  a long hydrocarbon and a short  ionic part .

• The hydrocarbon part of the soap molecule is soluble in oil or grease so it can attach to the oil and grease particles present on dirty clothes. The short ionic part of the soap molecule is soluble in water so it can attach to the water particles .

Submitted By Mrs. Kritika Bhola
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