Question

What happens when carbon di oxide is passed through lime water?Give the chemical reaction. Also what happens when CO2 is passed through EXCESS of lime water?Give the equation with explanation

Answer 1

Limewater is Ca(OH)2
When CO2 is passed,
CO2 + Ca(OH)2 ====> CaCO3 + H2O
The CaCO3 is a white precipitate, which turns the limewater milky.
When excess CO2 is passed,
CaCO3 + H2O ===> CaHCO3
Hence the CaCO3 gets converted to CaHCO3 which is soluble in water and thus the white colour vanishes.

Answer 2

     when $CO_2$ is passed through lime water,
It reacts with lime water to form limestone.

$CO_2(g)+Ca(OH)_2(s)-\ \textgreater \ CaCO_3 (aq)+H_2O(l)$
   carbon         calcium                                  calcium              water
  di-oxide       oxide                                      carbonate
                    (lime water)                               (limestone)

When excess $CO_2$ is passed, It forms a substance called calcium hydrogen carbonate which is soluble in water.

$Ca(OH)_2$+$CO_2$(excess)---> $Ca(HCO_3)_2(aq)$

              Hope it helps!!