Question

What are the products formed in sequence when excess of CO₂ is passed in slaked lime?

Options

• \[\ce{CaCO3, Ca(HCO3)2}\]

• \[\ce{Ca(HCO3)2, CaCO3}\]

• \[\ce{CaO, CaCO3}\]

• \[\ce{CaO, Ca(HCO3)2}\]

Answer 1

\[\ce{CaCO3, Ca(HCO3)2}\]

Explanation:

Slaked lime is an aqueous solution of Ca(OH)₂ which is used to identify the `"CO"_3^(2-)` and `"SO"_3^(2-)` ion in the given mixture. If CO₂ is passed in slaked lime then following reaction takes place.

\[\ce{Ca(OH)2 + CO2 -> \underset{(Insoluble in water)}{\underset{White}{CaCO3 \downarrow +}} H2O}\]

\[\ce{CaCO3 \downarrow + CO2 + H2O -> \underset{(Soluble in water)}{\underset{Colourless}{Ca(HCO3)2}}}\]

Calcium carbonate causes milkiness to appear, while calcium bicarbonate that is produced when there is too much CO₂ is soluble in water. Milkiness vanishes as a result.