chapter 4 carbon and its compound dec 2015 | Page 10

Esterification :
Carboxylic acids react with alcohols in presence of few drops of concentrated
sulphuric acid as catalyst and form sweet smelling compounds called ester.
Hydrolysis :
On heating with an acid or a base the ester forms back the original alcohol and
carboxylic acid.
CH3COO CH2CH3 + NaOH → CH3COONa + CH3-CH2OH
CH3COO CH2CH3

Dil.H 2 SO 4

→
HEAT

CH3COOH + CH3-CH2OH

*Alkaline hydrolysis of ester is also called saponification.
Soaps and Detergents
–

Soap is sodium and potassium salt of carboxylic acids with long chain.

–

Soaps are effective with soft water only and ineffective with hard water.

–

Detergents are ammonium or sulphonate salts of carboxylic acids with long
chain. They are effective with both soft as well as hard water.

An ionic part (hydrophilic) and a long hydrocarbon chain (hydrophobic) part
constitutes the soap molecule.

Structure of a Soap Molecule
Cleansing Action of Soaps :
–

Most dirt is oily in nature and the hydrophobic end attaches itself with dirt,
while the ionic end is surrounded with molecules of water. This result in
formation of a radial structure called micelles.

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X – Science

AK