Question

Compare hydration energy of $B{e}^{2+}$ and $A{l}^{3+}$.

Answer 1

Hydration energy is the energy evolved as heat when ions are hydrated. Higher is the degree of hydration, higher will be the hydration energy. Due to very small size and high electronegativity, the polarising power of $B{e}^{2+}$ is almost equal to the polarisation power of $A{l}^{3+}$. Hence, these two ions undergo hydration to similar extent. Hence, they have comparable hydration energies.