Question

On passing excess of co2 gas in an aqueous solution of calcium carbonate, milkiness of the solution

Answer 1

Carbon dioxide passed into limewater gives a milky solution, due to precipitation of an insoluble suspension of calcium carbonate: Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O. If excess CO2 is added, the following reaction
CaCO3(s) + H2O(l) + CO2(g) → Ca(HCO3)2(aq)
takes place: ... Themilkiness disappears since calciumbicarbonate is water-soluble.