Question

Which is correct order of solubility in water ?

(a) Ba(OH)₂ < Mg(OH)₂

(b) BaCO₃  > CaCO₃

(c) CaSO₄ < MgSO₄

(d) Ca(OH)₂ ≈ Mg(OH)₂

Answer 1

Correct option (c) CaSO₄ < MgSO₄

Explanation:

MgSO₄ is readily soluble in water The solubility of the sulphates of alkaline earth metals decreases with increase in size of the central metal ion. The greater hydration enthalpies of Mg²⁺ ions overcome the lattice enthalpy factor and therefore, MgSO₄ is more soluble in water.