The gas formed in an acid and metal carbonate reaction can make lime water clear again when passed in excess. What is the reason?
Answer and explanation
Correct answer: Soluble calcium hydrogen carbonate is formed
The governing reactions involve carbon dioxide and limewater. Initially, CO₂ reacts with calcium hydroxide to form insoluble calcium carbonate, producing a milky appearance: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. When excess CO₂ is passed, the precipitate reacts further to form soluble calcium hydrogen carbonate, Ca(HCO₃)₂. The precipitate dissolves, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
Soluble calcium hydrogen carbonate is formed
Why is this the correct answer?
The governing reactions involve carbon dioxide and limewater. Initially, CO₂ reacts with calcium hydroxide to form insoluble calcium carbonate, producing a milky appearance: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. When excess CO₂ is passed, the precipitate reacts further to form soluble calcium hydrogen carbonate, Ca(HCO₃)₂. The precipitate dissolves, so option A 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.
