Question

Why is sulphuric acid not used for the preparation of carbon dioxide in the laboratory 

Answer 1

Dilute sulphuric acid reacts with calcium carbonate. But it is not used because the calcium sulphate which is formed during the reaction is insoluble in water. It covers the marble chips and stops the reaction.

\[\ce{\underset{\text{(calcium carbonate)}}{CaCO3}+\underset{\text{(sulphuric acid)}}{H2SO4(dil.)}→\underset{\text{(calcium sulphate)}}{CaSO4}+\underset{\text{(water)}}{H2O}+ \underset{\text{(carbon dioxide)}}{CO2}}\]