Here's why:
* Lime water is a solution of calcium hydroxide (Ca(OH)₂).
* Exhaled breath contains carbon dioxide (CO₂) as a waste product.
* When carbon dioxide reacts with calcium hydroxide, it forms calcium carbonate (CaCO₃), which is insoluble in water.
The chemical reaction is:
Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l)
The milky white appearance is due to the formation of the insoluble calcium carbonate precipitate. This reaction is a classic test for the presence of carbon dioxide.
