After the aluminum rusts, its surface is grayish white or light yellow.
If the surface of aluminum is not passivated, it is easy to rust. It can be said that it rusts more easily than all iron alloys. The process of aluminum rusting is a series of chemical reactions. 2Al(OH)3 2H2
2Al(OH)3=>Al2O3 3H2O
The so-called passivation is to put aluminum in a strong sulfuric acid solution, because the film formed after the combination of sulfate ions and aluminum is relatively dense, so after corrosion it will prevent further corrosion and form a passivation layer.
It will rust. Rust, in fact, aluminum and oxygen combined to form aluminum rust - trialumina, or alumina for short. This layer of alumina is tightly attached to the surface of the aluminum and prevents the aluminum inside from combining with oxygen. This oxide film is very thin, it is only a little less than 0.00001 mm thick. Their surfaces are grayish white or pale yellow
It's black. Because the resulting alumina surface is not smooth, there is a diffuse reflection, so it looks black.
As if the copper wire was inserted into the silver nitrate solution to replace the silver elemental reaction, the silver elemental on the copper wire is black. However, in general questions, with some exceptions in laboratory questions, the answer is generally white. HAPPY NEW YEAR~