when carbon dioxide is passed into limewater, a white precipitate is formed. if carbon dioxide is passed continously into limewater, the white precipitate disappears. Explain why and give equations for the reactions.
When carbon dioxide (CO2) is passed into limewater (calcium hydroxide solution, Ca(OH)2), a white precipitate called calcium carbonate (CaCO3) is formed. This reaction can be represented by the following equation:
CO2 + Ca(OH)2 → CaCO3 + H2O
The white precipitate is formed because the carbon dioxide reacts with the calcium hydroxide to produce insoluble calcium carbonate. However, if carbon dioxide is continuously passed into limewater, the white precipitate disappears. This is due to the formation of a soluble compound called calcium bicarbonate (Ca(HCO3)2), which results from the reaction between the calcium carbonate and additional carbon dioxide:
CaCO3 + CO2 + H2O → Ca(HCO3)2
The formation of calcium bicarbonate makes the solution acidic, causing the calcium carbonate to dissolve. This is why the white precipitate disappears when carbon dioxide is continuously passed into limewater.