Question

Give reasons for the following. Give the chemical equation wherever required.

The milkiness of lime water disappears on adding CO₂ in excess.

Answer 1

When excess carbon dioxide is passed through lime water, the insoluble milky calcium carbonate reacts with water and CO₂ to form soluble calcium hydrogen carbonate.

\[ \text{CaCO}_3\text{ (s)} + \text{H}_2\text{O}\text{ (l)} + \text{CO}_2\text{ (g)} \longrightarrow \text{Ca(HCO}_3\text{)}_2\text{ (aq)} \]