Question

The solubilities of carbonates decrease down the magnesium group due to a decrease in
(a) lattice energies of solids
(b) hydration energies of cations
(c) interionic attraction
(d) entropy of solution formation.

Answer 1

(b) : The stability of the carbonates of the alkaline earth metals increases on moving down the group. The solubility of carbonate of metals in water is generally low. However they dissolve in water containing CO₂ yielding bicarbonates, and this solubility decreases on going down in a group with the increase in stability of carbonates of metals, and decrease in hydration energy of the cations.