Question

How does water get temporarily hard in nature? Give a proper reaction in support of your answer.

Answer 1

When the rainwater flows on the earth's surface, the carbon dioxide gas present in the air dissolves in it and then this water flows over the rock containing calcium carbonate or magnesium carbonate reacts with it and forms their respective hydrogen carbonates and hence it turns the water into hard water.

As the rainwater containing carbon dioxide combines with limestone and magnesite layers the following reaction

$\underset{\mathrm{calcium}\mathrm{bicarbonate}}{\underset{}{\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2}}\to \underset{\mathrm{calcium}\mathrm{carbonate}}{\underset{}{{\mathrm{CaCo}}_3}}+\underset{\mathrm{water}}{\underset{}{{\mathrm{H}}_2\mathrm{O}}}+\underset{\mathrm{carbon}\mathrm{dioxide}}{\underset{}{{\mathrm{CO}}_2}}$