Question

What happens when:

(a) CO₂ is passed through lime water in a limited quantity? 

(b) CO₂ is passed through lime water in excess?

Answer 1

(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