Question

Anhydrous $AlC{l}_3$ is covalent from the data given below predict whether it would remain covalent or ionic in aqueous solution.
$\text{Ionization energy for}AlC{l}_3=5137kJmo{l}^{-1}$
$\Delta H_{\text{hydration}}$ for $A{l}^{+3}=-4665kJmo{l}^{-1}$.
$\Delta H_{\text{hydration}}$ for $C{l}^{-}$ = -381 $kJmo{l}^{-1}$

• A. Ionic
• B. Covalent
• C. Cannot be predicted
• D. None of the above

Answer 1

The correct option is A Ionic

When hydration energy is greater than ionization energy, the bond is ionic. When lonization energy is greater than hydration energy the bond is covalent.
$\text{Hydration energy}=-4665-3\times 381=-5808kJmo{l}^{-1}$
lonization energy = $+5137kJmo{l}^{-1}$
$\therefore \text{Hydration energy + lonization energy}=-5808+5137$
$=-671kJmo{l}^{-1}$
Hydration energy is greater than Ionization energy
$\therefore AlC{l}_3$ becomes ionic in aqueous solution.