Question

On passing excess CO2 through lime water, it first turns milky and then becomes colourless. Explain why ? Write chemical equations.

Answer 1

When CO2 is passed through lime water , the lime water turns milky white due to formation of white precipitate of calcium carbonate.

Ca(OH)2 (aq) +CO2 -----> CaCO3 (s) +H2O(l)

If excess of Carbon dioxide is passed through lime water, then the white precipitate formed dissolves due to formation of a soluble salt calcium hydrogencarbonate and the solution becomes clear again.

CaCO3 + CO2(g) +H2O(l) --------> Ca(HCO3)2(aq)

Answer 2

Hey mate !!!!

due to formation of calcium hydrogen carbonate.

or formation of Sodium Bicarbonate.

Ca(OH)2 + co2 = CaCO3 + H20 .

CaCo3 + co2 ( excess) + H20 = Ca(HCO3)2 .

hope it helps!!!!

thanks

due to formation of calcium bicarbonate the milk colour of solution disappear.