Which has the larger hydration energy in each set?

Question

Which cation in each set is expected to have the larger (more negative) hydration energy?

I  Li⁺ or Cs⁺

II K⁺ or Al³⁺

Answer 1

In general, as the atomic size increases, the hydration energy decreases.

Comparing Li⁺ to Cs⁺, Cs⁺is larger than Li⁺, so Li⁺ would have the larger hydration energy.

Comparing K⁺ to Al³⁺, K⁺ is larger than Al³⁺, so Al³⁺ would have the larger hydration energy.