Question

Vinay was trying to create sodium acetate, he added ethanoic acid and ‘A’ in an open vessel. He also added few drops of concentrated $H_{2}S{O}_4$ to this and was surprised when the solution gave a sweet effervescence. So he repeated this experiment in a closed vessel and obtained ethyl acetate. Then he added ‘B’ and created sodium acetate. Find A and B.

• A. A - Ethanol; B - Washing soda
• B. A - Ethanol; B - Sodium hydroxide
• C. A - Ethanol; B - Baking powder
• D. A - Sodium acetate; B - Ethanol

Answer 1

The correct option is B A - Ethanol; B - Sodium hydroxide

Esters are formed by the reaction of carboxylic acids and alcohols. Ethanoic acid reacts with ethanol in the presence of dil. ${\text{H}}_2{\text{SO}}_4$ to give an ester. The reaction is represented as:

$C{H}_{3}COOH+C{H}_{3}C{H}_{2}OH\stackrel{dil.H_{2}S{O}_4}{\to }C{H}_{3}COO{C}_2{H}_5\left(Ester\right)+H_{2}O$

Esters are sweet smelling substances and are highly volatile. Hence when conducted in an open vessel, it evaporated. So, ethanoic acid reacts with ethanol to form sweet effervescence ethyl acetate. Compound 'A' is ethanol.

On treating with sodium hydroxide, the ester is converted back to alcohol and sodium salt of carboxylic acid is also formed. This reaction is known as saponification because it is used in the preparation of soap.

$C{H}_{3}COO{C}_2{H}_5+NaOH\to C_2{H}_{5}OH+C{H}_{3}COONa$

So, compound 'B' is sodium hydroxide.