Why can milky lime water become clear again when excess carbon dioxide is passed?
Answer and explanation
Correct answer: Because soluble calcium hydrogen carbonate is formed
Initially, carbon dioxide reacts with limewater to form insoluble calcium carbonate, which causes the milky appearance: CO2 + Ca(OH)2 → CaCO3 + H2O. When excess CO2 is passed, the calcium carbonate reacts further with carbon dioxide and water to form soluble calcium hydrogen carbonate, Ca(HCO3)2. The solid precipitate dissolves, so the solution becomes clear again; option D is correct.
Frequently asked questions
What is the correct answer to this question?
Because soluble calcium hydrogen carbonate is formed
Why is this the correct answer?
Initially, carbon dioxide reacts with limewater to form insoluble calcium carbonate, which causes the milky appearance: CO2 + Ca(OH)2 → CaCO3 + H2O. When excess CO2 is passed, the calcium carbonate reacts further with carbon dioxide and water to form soluble calcium hydrogen carbonate, Ca(HCO3)2. The solid precipitate dissolves, so the solution becomes clear again; option D is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
