Question

Anhydrous $AlC{l}_3$ is covalent but hydrated $AlC{l}_3.6H_{2}O$ is ionic because:

• A. $AlC{l}_3$ dissolves in $C{S}_2$
• B. $AlC{l}_3$ has planar structure
• C. $I.E.$ of $Al$ is low
• D. Hydration energy of $Al$ compensates the $I.E.$

Answer 1

Answer: (D)

Hydration energy of $Al$ compensates the $I.E.$

Due to high polarisation power of $A{l}^{+3}$, anhydrous $AlC{l}_3$ is covalent.
Once it is hydrated $AlC{l}_3+6H_{2}O\to \left[Al\right(H_{2}O{)}_6{]}^{3+}+3C{l}^{-}$
Hydration energy of $A{l}^{+3}$ is larger than Ionisation energy therefore, $AlC{l}_3\cdot 6H_{2}O$ is ionic.