Question

Identify the compound which gives CO\(_2\) more readily on heating.

• A. \( \text{CaCO}_3 \)
• B. \( \text{NaHCO}_3 \)
• C. \( \text{Na}_2\text{CO}_3 \)
• D. \( \text{Li}_2\text{CO}_3 \)

Hint:

Smaller cations (like Li\(^+\)) polarize the carbonate ion more, making decomposition easier. - Thermal stability trend: Li\(_2\)CO\(_3\)<Na\(_2\)CO\(_3\)<CaCO\(_3\) (Li\(_2\)CO\(_3\) decomposes at the lowest temperature).

Answer 1

The Correct Option is D

Step 1: The decomposition reaction of metal carbonates occurs as follows: \[ MCO_3 \rightarrow MO + CO_2 \] where \( M \) is a metal. Step 2: The thermal stability of metal carbonates decreases as we move up the group in the periodic table. - Lithium carbonate (Li\(_2\)CO\(_3\)) decomposes more easily than CaCO\(_3\), NaHCO\(_3\), and Na\(_2\)CO\(_3\) due to the small size of the Li\(^{+}\) ion, which distorts the carbonate ion, making it easier to decompose. Thus, the correct answer is \( \text{Li}_2\text{CO}_3 \).