A student uses lime water to test the gas evolved as a result of actio...
Answer:Introduction:
In this experiment, a student is using lime water to test the gas evolved as a result of the action of dilute hydrochloric acid (HCl) on solid sodium carbonate (Na2CO3). Lime water is a common solution used to detect the presence of carbon dioxide (CO2) gas. It is a solution of a chemical compound known as calcium hydroxide (Ca(OH)2).
Explanation:
When hydrochloric acid reacts with sodium carbonate, it produces carbon dioxide gas, water, and a salt. The balanced chemical equation for this reaction is:
2HCl + Na2CO3 → 2NaCl + H2O + CO2
The carbon dioxide gas produced during this reaction can be tested using lime water. Lime water, which is a clear, colorless solution, turns milky or cloudy when carbon dioxide gas is bubbled through it. This is due to the formation of a white precipitate called calcium carbonate (CaCO3). The reaction between carbon dioxide gas and calcium hydroxide can be represented as:
CO2 + Ca(OH)2 → CaCO3 + H2O
The white precipitate of calcium carbonate gives the lime water its milky appearance.
Conclusion:
Therefore, the chemical compound present in lime water is calcium hydroxide (Ca(OH)2), which reacts with carbon dioxide gas produced during the reaction between hydrochloric acid and sodium carbonate to form calcium carbonate (CaCO3).