Question

How would you explain ? 

(i) BeO is insoluble but BeSO₄ is soluble in water. 

(ii) BaO is soluble but BaSO₄ is insoluble in water.

Answer 1

(i) Be²⁺ & O^2– smaller in size & thus higher lattice energy and lattice energy is greater than hydration energy in BeO where as in BeSO₄ lattice energy is less due to bigger sulphate ion and is soluble. 

(ii) In BaSO₄ lattice energy is greater than hydration energy while in BaO lattice energy is smaller than hydration energy.