What happens when excess carbon dioxide is driven into clear limewater?
Answer: Passing CO2 through clear limewater, first produces insoluble white calcium carbonate. As a result, lime water becomes cloudy.
Ca(OH)2 + CO2 = CaCO3 ↓ + H2O
Passing excess CO2 through this turbid lime water turns the insoluble calcium carbonate into soluble calcium bicarbonate. As a result, the cloudy lime water becomes clear again.
CaCO3 + H2O + CO2 = Ca(HCO3)2