(a) Esters are sweet-smelling substances and are used in making perfumes. Describe an activity for the preparation of an ester with the help of a well labelled diagram. Write an equation for the chemical reaction involved in the formation of the ester. Also write the names of all the substances involved in the process of esterification.
(b) State any two uses of esters.

An ester is formed when ethanol (alcohol) reacts with ethanoic acid, on heating, in the presence of a few drops of concentrated sulphuric acid by the process of esterification.
The name of the ester formed is ethyl ethanoate.
The activity for the preparation of an ester with the help of a well-labelled diagram is given below:
  1. Take 1 ml of pure ethanol (absolute alcohol) in a test-tube and add 1 ml of glacial ethanoic acid to it. Then add 2 or 3 drops of concentrated sulphuric acid to the mixture.
  2. Warm the test-tube containing above reaction mixture in a hot water bath (a beaker containing hot water) for about 5 minutes.
  3. Pour the contents of the test-tube in about 50 ml of water taken in another beaker and smell it.
  4. A sweet smell is obtained indicating the formation of an ester.
 

The chemical equation involved in the formation of the ester is given below:

$CH_3COOH + C_2H_5OH \xrightarrow {Conc. H_2SO_4}  CH_3COOC_2H_5 + H_2O$

(b) Uses of ester:

  •  Esters are used in making artificial perfumes because of their sweet fragrance.
  • Esters are used as flavouring agents in ice-creams, sweets and cold drinks.

Updated on: 10-Oct-2022

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