Question

The hydration energy of $M{g}^{2+}$ ionis lower than that of:

• A. $A{l}^{3+}$
• B. $C{a}^{2+}$
• C. $N{a}^{+}$
• D. none of these

Answer 1

Answer: (A)

$A{l}^{3+}$

Hydration energy is the amount of energy released when a mole of ion dissolves in large amount of water forming a dilute solution. The hydration energies decreases as enthalpy of hydration with the increase in atomic number and atomic size. The hydration energy of magnesium ion is $-1921kJ/mol$ and of aluminium ion is $-4665kJ/mol$.