Explain thermal stability increases from Li2CO3 to K2CO3

Question

Please describe for five marks

Answer 1

Hi Ashis,

 

Li₂CO₃ and K₂CO₃ are both group-1 or alkali metal carbonates. Lithium is higher up in the group than potassium and it has a higher first ionization energy than potassium. It is harder to remove the outermost electron in Li than in K making it more covalently bonding than K.

                  

Li₂CO₃  ----Δ-----> Li₂O + CO₂                                   Δ = heating

K₂CO₃   ----Δ-----> K₂O + CO₂

Both of the compounds decompose but thermal stability increases as one moves down the group. The reason is that lithium is small size exhibit a stronger ionic charge than potassium, therefore bonding more covalently with the carbon atom in CO₃^- .