Question

Why is $L{i}_{2}C{O}_3$ decomposed at a lower temperature whereas $N{a}_{2}C{O}_3$ at higher temperature?

Answer 1

$\text{Stability of carbonates}:$

As the electropositive character increases down the group, the stability of the carbonates increases.

Lithium carbonate is not so stable to heat because lithium being very small in size, so it polarises a large $C{O}_3^{2-}$ ion. So due to this it gets covalent character in ionic bond and become less stable.


Hence due to this, it leads to the formation of more stable $L{i}_{2}O$ and $C{O}_2$.

$L{i}_{2}C{O}_3\to L{i}_{2}O+C{O}_2$

Therefore, lithium carbonate decomposes at a low temperature while a stable sodium carbonate decomposes at a high temperature.