Question

Why Li₂CO₃ decomposes at lower temperature whereas Na₂CO₃ at higher temperature?

Answer 1

Li⁺ ion is smaller in size. It forms more stable lattice with smaller anion oxide, O^2- than with CO₃^2- ion. Therefore, Li₂CO₃ decomposes into Li₂O at lower temperature on the other hand, Na⁺ ion being larger in size forms more stable lattice with larger anion CO₃^2-than with O^2- ion. Therefore, Na₂CO₃ is quite stable and decomposes into Na₂O at very high temperature.