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Question
Give a scientific reason.
When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky.
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Solution
- When limestone is heated, calcium oxide and carbon dioxide gas are formed.
\[\ce{\underset{\text{carbonate}}{\underset{\text{Calcium}}{CaCO_{3(s)}}} + Heat -> \underset{\text{oxide}}{\underset{\text{Calcium}}{CaO_{(s)}}} + \underset{\text{dioxide}}{\underset{\text{Carbon}}{CO2\uparrow}}}\] - When carbon dioxide gas is passed through freshly prepared lime water, the solution turns milky due to the formation of calcium carbonate, which is insoluble in water.
\[\ce{\underset{\text{hydroxide}}{\underset{\text{Calcium}}{Ca(OH)2_{(aq)}}} + \underset{\text{dioxide}}{\underset{\text{Carbon}}{CO_{2(g)}}} -> \underset{\text{carbonate}}{\underset{\text{Calcium}}{CaCO_{3(s)}}} + \underset{\text{Water}}{H2O_{(l)}}}\]
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