Question

A substance 'X' is used as a building material and is insoluble in water. When it reacts with dil. HCl, it produces a gas which turns lime water milky.

1. Write the chemical name and formula of 'X'.
2. Write chemical equations for the chemical reactions involved in the above statements.

Answer 1

(i) Substance X is calcium carbonate \[\ce{(CaCO_3)}\] or limestone.

(ii) \[\ce{\underset{carbonate (X)}{\underset{Calcium}{CaCO3(s)}} + \underset{dil.}{2HCl(l)}->\underset{chloride}{\underset{Calcium}{CaCl2}} + H2O(l) + CO2(g)\uparrow}\]

Carbon dioxide gas \[\ce{(CO2)}\] evolved turns lime water milky.

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