When carbon dioxide is passed in excess, calcium carbonate (which appears milky) gets converted into calcium hydrogen carbonate which is soluble. Hence, the milkiness disappears.
CaCO3 + H2O + CO2 → Ca(HCO3)2
When carbon dioxide is passed in excess, calcium carbonate (which appears milky) gets converted into calcium hydrogen carbonate which is soluble. Hence, the milkiness disappears.
CaCO3 + H2O + CO2 → Ca(HCO3)2