Question

(a) When ethanoic acid reacts with sodium hydrogen carbonate, then a salt X is formed and a gas Y is evolved. Name the salt X and gas. Y Describe an activity with the help of a labelled diagram of the apparatus used to prove that the evolved gas is the one which you have named. Also write the chemical equation of the reaction involved.
(b) Give any two uses of ethanoic acid.

Answer 1

(a) When ethanoic acid reacts with sodium hydrogen carbonate, a brisk effervescence of carbon dioxide gas (Y) is evolved. The salt (X) formed as a result of this reaction is sodium ethanoate.

Let's react ethanoic acid with sodium hydrogen carbonate.

(i) Take a boiling tube and add 0.5gm of sodium hydrogen carbonate to it. To this, add 2 ml of dilute ethanoic acid through a thistle funnel.
(ii) You will notice a brisk effervescence of carbon dioxide gas.
(iii) Take a test tube containing lime water and pass the carbon dioxide gas through it.
(iv) You will observe the lime water turning milky. Carbon dioxide is the only gas which turns lime water milky.

This activity proves that carbon dioxide gas is evolved when ethanoic acid reacts with sodium hydrogen carbonate.
The diagram of the entire experiment is shown below:


The chemical equation of the above reaction is as follows:
${\mathrm{CH}}_3\mathrm{COOH}+{\mathrm{NaHCO}}_3\to {\mathrm{CH}}_3\mathrm{COONa}+{\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}$

(b) Uses of ethanoic acid:

(i) Ethanoic acid is used in the preparation of plastics, dyes and pharmaceuticals.
(ii) Dilute ethanoic acid (vinegar) is used as a food preservative, and as an appetiser in dressing food dishes.