Question

anhydrous alcl3 is covalent but alcl3.6h2o is ionic because

Answer 1

AlCl3 is covalent but AlCl3.6H2O is ionic...
because first of all the Third ionization enthalpy of Al is very high....so a lot of energy is required to convert Al to Al3+
Al(g) + 5114 kJ/mol. ---------> Al3+(g) + 3e-
therefore it prefers to form covalent bonds with Cl atoms...
However when AlCl3 is dissolved in water it undergoes hydration releasing a lot of energy..
AlCl3+H2O -------> AlCl3.6H2O + Energy
This energy is enough to remove 3e- from Al atom..
In fact Al does not exist as Al3+ but exist as [Al(H2O)6]+

[Al(H2O)6]+ + Cl-

Thus , hexahydrated aluminium chloride is ionic in nature..
Thank u..

Answer 2

Answer:

Hydration energy of $Al^{+3}$is larger than ionization energy therefore, AlCl3⋅6H2O is ionic. Anhydrous AlCl3 is covalent but AlCl3.6H2O is ionic .

Explanation:

• When hydration energy is greater than ionization energy, the bond is called ionic.

• When lionization energy is greater than the hydration energy ,the bond is  called covalent.

• Due to high polarization power of $Al^{+3}$ ,  anhydrous AlCl3​  is covalent.

• Once it is hydrated   AlCl3 + 6H2O → [Al(H2O) 6 ​ ] 3+ + 3Cl −
• Hydration energy of Al+3  is larger than Ionization energy therefore, $AlCl^{3}$ ⋅6$H_{2}$ $O_{}$ is ionic.