|MadSci Network: Chemistry|
Since the metal rod responds to a magnet, it is probably either Fe, Ni, or Co, or a Stainless steel alloy, or [very unlikely] something like Alnico. It is most probably Fe or some Fe alloy. Aluminum Nitrate solutions are slightly acidic, and will attack [corrode] some metals. The bubbles are probably hydrogen, and the "tea" color is probably due to dissolved iron in solution as ferric nitrate. A metal in contact with a solution of its own salts [ say, Al in Al nitrate] will generate a potential that can be predicted from the EMF tables, etc. But a metal in contact with a salt of another metal forms a potential which is very hard to predict. Also, when you attach the steel wool, you add a third metal to the situation which makes things even more complex. Also, the steel wool may now be reacting with the unknown metal rod, generating a different potential. I suggest that you test the solution for the presence of Fe. I do not know what chemicals you have available in your laboratory for testing. One easy one is to prepare a dilute [say, 1-10 %] solution of Potassium ferrocyanide. To a few drops of this add a few drops of the colored solution. An intense blue-black color ["Prussian Blue"] will indicate Iron. Try this on a known Iron salt first.
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