Question #b01a3

1 Answer
Oct 5, 2015

The 1st case involves hydrolysis. The 2nd case is just dilution so is not really a reaction.

Explanation:

Aluminium chloride is a white solid which reacts vigorously with water to give hydrated Al3+ ions and Cl ions:

Al2Cl6+12H2O2[Al(H2O)6]3++6Cl

The small, highly charged Al3+ weakens the OH bonds resulting in a hydrolysis reaction:

[Al(H2O)6]3+ +H2O[Al(H2O)5OH]2++H3O+

The resulting solution is, therefore, quite acidic.

Hydrated aluminium chloride cannot exist as a solid for this reason so adding water to its solution will simply dilute it.