What are the products formed in sequence when excess of CO₂ is passed in slaked lime?

Solution

Chemistry ma’am · 3 steps

First the milky carbonate forms, then extra CO₂ dissolves it as bicarbonate, so watch the order.

1. First portion. Slaked lime is Ca(OH)₂. A little CO₂ turns it into insoluble calcium carbonate, which is why lime water turns milky.

   Ca(OH)₂ + CO₂ → CaCO₃ v + H₂O

2. Excess CO2. More CO₂ reacts with this carbonate and water to give calcium hydrogencarbonate, CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂. It is soluble, so the milkiness disappears.
3. So. The sequence is CaCO₃ first, then Ca(HCO₃)₂. That is option (b).

The idea to keep. Lime water plus CO₂: milky from CaCO₃, then clear again with excess as soluble Ca(HCO₃)₂. Bicarbonate can only form from carbonate that already exists.

Answer from the NTA final answer key. Solution by PrepWiser.