Anhydrous `AlCl_(3)` is covalent but hydrated `AlCl_(3)` is electrovalent. Explain.

Explanation

Anhydrous salt exists as a dimer `Al_(2)Cl_(6)` and is covalen t in nature. In contact with water, it gests hydrated and the hydrated salt `[Al(H_(2)O)_(6)]Cl_(3)` becomes ionic. In fact, during hydration, a large amount of hydration energy is released which helps in the inoisation of the salt.
`[Al(H_(2)O)_(6)]Cl_(3)hArr[Al(H_(2)O)_(6)]^(3+)+3Cl^(-)`