Question

While conducting an experiment in the laboratory, Rahul accidently spilled
few drops of concentration Hydrochloric acid on the marbled table top. He
could observe some reaction taking place. Write a chemical equation for the
reaction involved and explain his observation.
(b) How is universal indicator more useful than other indicators?

Answer 1

Explanation:

Marble is basically Calcium carbonate (CaCO3)

Carbon dioxide gas is evolved when concentrated HCl reacts with marble .

Reaction takes place as follows:-

CaCO3 (s) + HCl (conc.) –› CaCl2 (aq) + H2O (l) + CO2 (g)

(b) Universal indicator also tells us how strong the acidic or basic solution is. Others indicators like litmus paper etc. tells us only weather the given solution is acidic or basic but universal indicator also gives the pH of given solution.