Question

When slaked lime is passed through excess \( \mathrm{CO_2} \), it forms

• A. \( \mathrm{CaCO_3} \)
• B. \( \mathrm{CaCl_2} \)
• C. \( \mathrm{Ca(HCO_3)_2} \)
• D. \( \mathrm{Ca_2HCO_3} \)

Hint:

Excess \( \mathrm{CO_2} \) converts insoluble carbonates into soluble bicarbonates.

Answer 1

The Correct Option is C

Step 1: Reaction of slaked lime with carbon dioxide.
Slaked lime is calcium hydroxide, \( \mathrm{Ca(OH)_2} \). With limited \( \mathrm{CO_2} \), it forms calcium carbonate.

Step 2: Effect of excess \( \mathrm{CO_2} \).
When excess carbon dioxide is passed, calcium carbonate further reacts to form soluble calcium bicarbonate.

Step 3: Chemical equation.
\[ \mathrm{Ca(OH)_2 + 2CO_2 \rightarrow Ca(HCO_3)_2} \]

Step 4: Conclusion.
Thus, calcium bicarbonate is formed when slaked lime is treated with excess \( \mathrm{CO_2} \).