Question

A white solid 'A' when reacts with hydrochloric acid gives a colourless & odourless gas 'B' which turn lime water milky . Solid 'A' when heated decomposes to give a solid 'C' & gas 'B' . Solid 'C' used in white washing of wall . Identify the substances A, B & C and write the chemical equation for reactions wherever taking place.​

Answer 1

Explanation:

• A white solid 'A' – $\mathrm{CaCO}_{3}$ when reacts with the ‘hydrochloric acid’ gives a “colourless & odourless” gas 'B' – $\mathrm{CO}_{2}$which turns into lime water milky.
• Solid ‘A’ - $\mathrm{CaCO}_{3}$ when heated decomposes to give a solid 'C' - CaO & gas 'B'- $\mathrm{CO}_{2}.$
• Solid 'C'- CaO used in white washing of wall.  

• ${CaCO}_3$reacts with the hydrochloric acid to give colorless carbon-dioxide.

The chemical reaction is as follows:

$\mathrm{CaCO}_{3}+\mathrm{HCl} \rightarrow \mathrm{CaCl}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}$

• ${CO}_{2}$ gas turns lime water milky.

• Heating of ${CaCO}_3$ gives calcium oxide (CaO) and carbon dioxide. The chemical reaction is as follows.

$\mathrm{CaCO}_{3} \rightarrow \mathrm{CaO}+\mathrm{CO}_{2}$