6D.11 parts e and f

[rita_h]

Why do we add hydrates in parts e and f? To Aluminum and Copper?

[Grace Chang 1E]

Hi!

In part e (AlCl3), you know that Cl- will not react because it is the conjugate base of a strong acid—thus, it is completely stable existing as a Cl- ion in water. However, Al is the conjugate acid of a weak base (you know that it must be a weak base because Al is not an alkali or alkaline earth metal). Thus, because Al is the conjugate acid of a weak base, it will make the solution acidic.

The same logic can be applied to Cu—it is the conjugate acid of a weak base, so it will also make the solution acidic.

[rita_h]

My question is, why is it that in the correction, the equations were shown as follows:
Al(H2O)6 3+ + H2O --> H3O+ + Al(H2O)5 OH 2+
Cu(H2O)6 2+ + H2O --> H3O+ Cu(H2O)5 OH +
Where did the hydrate groups attached to Al and Cu come from?