# Is aluminium foil pure aluminium? [closed]

Is aluminium foil pure aluminium? Or does it have other elements in the e.g: tin (Sn) or lead (Pb)? Because when I try to oxidize it through the process of submerging it in water, it doesn't look like it wants to oxidize to aluminium oxide (AlO+). I did this exact same thing with pure aluminium and it oxidized within minutes.

• Aluminium foil is pure Al covered with some polymer. Sn or Pb are definitely not a part of the picture. – Ivan Neretin Jan 11 at 7:15
• You can try cleansing with eg acetone or ethanol or detergent and see if the coating is removed – Alchimista Jan 11 at 8:20
• Aluminium won't oxidise by submerging it in water any more than it does in air. Pure aluminium is covered in a tough but very thin layer of aluminium oxide which will protect the bulk metal from further reaction with air or water unless the protective layer is disrupted. Your "pure" aluminium was probably just treated with something that disrupted the normal protective layer. – matt_black Jan 12 at 14:58
• @matt_black It was taken out of a emergency water light which had other chemicals like CU and some black coating, it did produce electricity(obviously); the electricity helped it remove the 'protective layer'? – SF12 Study Jan 17 at 6:51

## 2 Answers

From the Institute of Minerals, Materials and Mining,

Most aluminium foil is made from pure aluminium, but increasingly alloys are used to improve properties and reduce the thickness required.

If you want to make sure that the Aluminium foil you're using is pure, the only way would probably to ask the manufacturer. Other than that, it could be the case that the foil is either pure or alloyed, depending on how it's made.

Reynolds Kitchens says Relnolds Wrap® is $$98.5\%$$ $$\ce{Al}$$ with the rest mostly $$\ce{Fe}$$ and $$\ce{Si}$$ to improve strength. You know this because when you dissolve it in $$\ce{NaOH}$$ solution to produce $$\ce{H_2}$$ a black residue remains undissolved; pure $$\ce{Al}$$ metal would leave no residue. Perhaps $$\ce{Al}$$ wiring would be more nearly pure because small impurities decrease electrical conductivity. $$\ce{Cu}$$ for bus tubing is cast in a $$\ce{N_2}$$ atmosphere for this reason: $$\ce{O_2}$$ from the air would otherwise contaminate the metal.

• NaOH = Sodium Peroxide? Are there any other chemicals that I could dissolve it in? Like NaHCl? – SF12 Study Jan 17 at 6:49
• $\ce{NaOH}$ is sodium hydroxide, commonly called lye. Aluminum is amphoteric so it can dissolve in strong acid or base. $\ce{NaHCl}$ isn't a chemical; maybe you mean $\ce{HCl}$ hydrochloric acid, also called muriatic acid? – user5713492 Jan 17 at 7:56
• dang, got the name wrong I was tryna say NaOCl. – SF12 Study Jan 23 at 6:28