Shouldn't aluminium oxide be reactive?

[Kyoma]

Once exposed to air, aluminium would form a layer of aluminium oxide, which would render it unreactive in acids.

But, aluminium oxide is an amphoteric oxide. Shouldn't it be reactive in acids?

 

[Borek]

It reacts with acids, just slowly.

 

[Kyoma]

Okay, thanks for the help.

 

[Nemus]

I agree with Borek but to expand a bit on the subject; if you put aluminum in base where the amphoteric oxide (actually the hydroxide) gets ionized to aluminate ions, which are soluble and leaves the surface, it reacts like crazy.

 

[ZealScience]

It's stable ONLY to normal conditions, like resistant to oxidation. But it still reacts with acid, not quite fast. Normal acid rain would do only little harm to it, if you have framework made of aluminum, don't be afraid of errosion, and I guess you don't pour concentated sulpuric acid onto it!