The gas produced on heating calcium carbonate turns lime water milky. Which gas is it?
Answer and explanation
Correct answer: Carbon dioxide
Calcium carbonate undergoes thermal decomposition on heating to form calcium oxide and carbon dioxide: \(\mathrm{CaCO_3 \xrightarrow{\Delta} CaO + CO_2}\). The released \(\mathrm{CO_2}\) reacts with lime water, \(\mathrm{Ca(OH)_2}\), forming insoluble calcium carbonate: \(\mathrm{CO_2 + Ca(OH)_2 \rightarrow CaCO_3 \downarrow + H_2O}\). This precipitate makes the lime water appear milky. Oxygen does not form this precipitate with lime water.
Frequently asked questions
What is the correct answer to this question?
Carbon dioxide
Why is this the correct answer?
Calcium carbonate undergoes thermal decomposition on heating to form calcium oxide and carbon dioxide: \(\mathrm{CaCO_3 \xrightarrow{\Delta} CaO + CO_2}\). The released \(\mathrm{CO_2}\) reacts with lime water, \(\mathrm{Ca(OH)_2}\), forming insoluble calcium carbonate: \(\mathrm{CO_2 + Ca(OH)_2 \rightarrow CaCO_3 \downarrow + H_2O}\). This precipitate makes the lime water appear milky. Oxygen does not form this precipitate with lime water.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
