What happens when:
(a) CO2 is passed through lime water in a limited quantity?
(b) CO2 is passed through lime water in excess?
a. When CO2 is passed through lime water in a limited quantity than calcium carbonate gets precipitated as a white colour mass at the bottom of the test tube according to the following reaction: -
Ca(OH)2 + CO2→ CaCO3 + H2O
b. When CO2 is passed through lime water in excess then the white precipitate initially formed gets dissolved forming Ca(HCO3)2 which is soluble in water as per the following reaction: -
CaCO3 + H2O + CO2→ Ca(HCO3)2