Question

Which of the following has higher hydration energy?

• A. $Mg{SO}_4$
• B. $Ra{SO}_4$
• C. $Sr{SO}_4$
• D. $Ba{SO}_4$

Answer 1

The correct option is A $Mg{SO}_4$

$MgS{O}_4$ has higher hydration energy. Magnesium cation has a smaller ionic radius, therefore the sulphate ion can be held more tightly so the lattice enthalpy is higher.However the hydration enthalpy of the magnesium sulphate is even higher because the delta +ve oxygen in the water molecule is more attracted to the small cation.