Question

The correct order of solubility of the sulphates of alkaline earth metals in water is $Be > Mg > Ca > Sr > Ba$. This is due to

• A. decreasing lattice energy
• B. high heat of solvation for smaller ions like $Be^{2+}$
• C. increase in melting points
• D. increasing molecular weight

Answer 1

Answer: (B)

high heat of solvation for smaller ions like $Be^{2+}$

Answer 2

As we move down the group from ${BeSO_4}$ to ${BaSO_4}$, the enthalpy of hydration of the positive ion becomes smaller due to increase in ionic size. Salts of heavier metal ions are less soluble than those of lighter ions.