Question

ON PASSING EXCESS CO2 GAS THROUGH LIME WATER IT FIRST TURN MILKY AND THEN BECOME COLOURLESS. EXPLAIN WHY WRITE ALL THE CHEMICAL REACTION INVOLVED

Answer 1

it turns milky due to the formation of calcium carbonate
but when excess of co2 is passed it turns into a precipitate of calcium carbonate and water remains colourless
EQ
Ca(OH)2+CO2---- CaCO3

Answer 2

Explanation :

When the excess carbon dioxide gas is passed through the lime water, it turns milky first due to the formation of the calcium carbonate as a precipitate which is insoluble in water and then become colorless due to the formation of calcium bicarbonate.

The balanced chemical reaction will be,

$Ca(OH)_2(l)+CO_2(g)\rightarrow CaCO_3(s)+H_2O(l)$

On passing excess of carbon dioxide gas, the colorless calcium bicarbonate is formed.

The balanced reaction will be,

$CaCO_3(s)+H_2O(l)+CO_2(g)\rightarrow Ca(HCO_3)_2(aq)$