Question

A spatula full of sodium carbonate is taken in a test tube and 2 mL of dilute ethanoic acid is added to it.

Suggest a method of testing the gas liberated in the reaction.

Answer 1

To test the gas liberated in the reaction between sodium carbonate and dilute ethanoic acid, carbon dioxide (CO₂) passed through lime water (calcium hydroxide solution). If carbon dioxide is present, it reacts with the lime water to produce calcium carbonate, a white precipitate that turns the lime water milky. The change indicates the existence of carbon dioxide. The chemical reaction for this test is as follows:

\[\ce{CO2(g) + Ca(OH)2(aq) -> CaCO3(s) + H2O(l)}\]

This method effectively demonstrates the presence of carbon dioxide gas evolved during the reaction​.