Question

On passing excess co2 through lime water it first turns milky and then colourless.explain why?write all chemical equation of reactions involved

Answer 1

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On passing excess CO2 through lime water, it initially becomes milky. This is because of the formation of calcium carbonate i.e. a white precipitate.

However, if excess of CO2 is passed through lime water then it turns colourless. This is because of the formation of calcium bicarbonate which is colourless in nature.

The reactions are as follows:-

1) CaO + CO2 = CaCO3

2) CaCO3 + CO2 + H2O = Ca(HCO3)2