Q7) On passing excess CO2 through lime water, it first turns
milky and then becomes colourless. Explain why? Write
chemical equations.
Answers
Explanation:
When the excess carbon dioxide gas is passed through the lime water, it turns milky first due to the formation of the calcium carbonate as a precipitate which is insoluble in water and then become colorless due to the formation of calcium bicarbonate.
The balanced chemical reaction will be,
Ca(OH)_2(l)+CO_2(g)\rightarrow CaCO_3(s)+H_2O(l)Ca(OH)
2
(l)+CO
2
(g)→CaCO
3
(s)+H
2
O(l)
On passing excess of carbon dioxide gas, the colorless calcium bicarbonate is formed.
The balanced reaction will be,
CaCO_3(s)+H_2O(l)+CO_2(g)\rightarrow Ca(HCO_3)_2(aq)CaCO
3
(s)+H
2
O(l)+CO
2
(g)→Ca(HCO
3
)
2
(aq)
Answer:When CO2 is passed through lime water , the lime water turns milky white due to formation of white precipitate of calcium carbonate.
Ca(OH)2 (aq) +CO2 -----> CaCO3 (s) +H2O(l)
If excess of Carbon dioxide is passed through lime water, then the white precipitate formed dissolves due to formation of a soluble salt calcium hydrogen carbonate and the solution becomes clear again.
CaCO3 + CO2(g) +H2O(l) --------> Ca(HCO3)2(aq)