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Question
A clear solution of slaked lime is made by dissolving Ca(OH)2 in an excess of water. This solution is left exposed to air. The solution slowly goes milky as a faint white precipitate forms. Explain why a faint white precipitate forms, support your response with the help of a chemical equation.
Solution
Calcium hydroxide reacts with Carbon dioxide present in the atmosphere to form Calcium carbonate which results in milkiness / white ppt / Formation of Calcium carbonate.
\[\ce{Ca(OH)2}\ + \ce{CO2}\ \ce{->}\ \ce{CaCO3}\ + \ce{H2O}\]
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