Question

Be and Mg sulphate are soluble in water but Cr,Sr & Ba sulphate are not soluble in water . why?

Answer 1

Sulphates of beryllium and magnesium are water soluble while those of Ca, Sr and Ba are not because the hydration energy decreases form Be²⁺ to Ba²⁺ as the size of the cation increases down the group. The insolubility of sulphates take place due to decrease in the hydration energies and those of beryllium and magnesium are water soluble because of their high hydration energies owing to their smaller cationic sizes.