Question

When excess of carbon dioxide is passed through lime water, the milkiness first formed disappears due to:

• A. the reversible reaction taking place
• B. formation of water soluble calcium bicarbonate
• C. huge amount of heat evolved during the reaction
• D. formation of water soluble complex of calcium.

Answer 1

The correct option is B formation of water soluble calcium bicarbonate

Answer:- (B) formation of water soluble calcium bicarbonate

When $C{O}_2$ is passed through lime water, it turns milky due to the formation of calcium carbonate which is sinsoluble in water.

$\underset{limewater}{Ca{\left(OH\right)}_2}+C{O}_2⟶\underset{milkiness}{CaC{O}_3}+H_{2}O$

However, when excess of $C{O}_2$ is passed through this solution, the milkiness disappears. This is due to the formation of calcium bicarbonate which is colorless and soluble in water.

$\underset{milkiness}{CaC{O}_3}+H_{2}O+\underset{excess}{C{O}_2}⟶\underset{\text{water soluble}}{Ca{\left(HC{O}_3\right)}_2}$