Chapter 7, Problem 2A

Interpretation Introduction

Interpretation :

The evidence for the heating of a chalk to be a chemical reaction must be explained.

Concept Introduction :

Chalk contains calcium carbonate (CaCO₃).

Answer to Problem 2A

When chalk is heated then calcium carbonate is decomposed to produce CaO (powder) and carbon dioxide gas which escapes.

Explanation of Solution

Thermal decomposition of CaCO₃ is given below.

  ${\text{CaCO}}_{\text{3}}\text{(s)}\to {\text{CaO(s)+CO}}_{\text{2}}\text{(g)}\text{.}$

As carbon dioxide escapes from the reaction vessel so mass is reduced. CaCO₃ is converted to CaO which is powder. Thus heating of a chalk is a chemical reaction.

Conclusion

Heating of chalk is a chemical reaction as new products are generated with different properties.