Question

The thermal stability of $BaC{O}_3,CaC{O}_3$ and $MgC{O}_3$ is:

• A. $CaC{O}_3>MgC{O}_3>BaC{O}_3$
• B. $MgC{O}_3>CaC{O}_3>BaC{O}_3$
• C. $BaC{O}_3>MgC{O}_3>CaC{O}_3$
• D. $BaC{O}_3>CaC{O}_3>MgC{O}_3$

Answer 1

The correct option is D $BaC{O}_3>CaC{O}_3>MgC{O}_3$

On moving down the group of alkaline earth metals, the thermal stability of carbonates increases. As the atomic number increases, the difference in the stability of metal cation and the oxide anion increases. Thus, the stability of the decomposition product metal oxide decreases, as close packing is not possible. Hence, the stability of the carbonate increases. Thus, among the given carbonates, the order of thermal stability is $BaC{O}_3>CaC{O}_3>MgC{O}_3$.