What happens when excess carbon dioxide is passed through lime water?

When excess CO₂ is passed through lime water, the initially white precipitate dissolves and the solution clears.

Step 1: (Limited CO₂): Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O (lime water turns milky)

Step 2: (Excess CO₂): CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂(soluble-solution clears)

Excess CO₂ converts insoluble CaCO₃ into soluble Ca(HCO₃)₂, clearing the initially milky lime water.