Ahh.. I see. I carried out the experiment last Friday and basically got the desired results. The NaOH dissolved while the NH4OH did not. Could someone please elaborate on what AWK responded with on why one dissolved and one didn't? I looked up intrinsic properties and did not get very far.
What I was told was:
The reason that the precipitate dissolves in one of the solutions is because the equilibrium moves to the right until Al(OH)3(s) is precipitated; this easily reacts with excess NaOH to give the aluminate ion, Al(OH)4-(aq). Basically, the Al(OH)3 is complexed to create an ion that dissolves in solution.
I do not know if this answer is credible, but someone said that was the reason.
The chemical equation for this is a double replacement for both solutions, is it not?