I was a chemistry major and have recently started watching this series of videos by NurdRage.

I learned that Platinum dissolves in Aqua Regia but Ruthenium is only attacked by high temperature halogens and some alkalis.


Would a Ruthenium and Platinum alloy be resistant to both acid and alkali?

But more importantly, is there any alloy or pure metal that is completely chemically inert to every strong oxidizing reagent? Is there any research about the most chemically inert metal alloys?

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    $\begingroup$ There is no completely inert material. However, in case you work with relatively small temperatures (<200 celsium) teflon is considered (almost) inert. $\endgroup$ – permeakra Jan 3 '13 at 18:27
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    $\begingroup$ Not an alloy, but this came up in a question about noble gas fluorides - fluorine forms a passivated layer on nickel which is tremendously corrosion resistant. As such, fluorine-passivated nickel vessels are used for fluorine photolysis experiments. $\endgroup$ – Richard Terrett Jan 4 '13 at 2:58
  • $\begingroup$ Why should some alloy be more resistant to oxidation than the "best" of its constituents? And do not mix up passivation (like aluminium) and chemical inertness! $\endgroup$ – Georg Apr 16 '13 at 10:44
  • $\begingroup$ Alloys have special properties that can exceed those of their constituents. $\endgroup$ – Cris Stringfellow Apr 16 '13 at 12:08

Due to electronegativities no alloy would be thermodynamically stable in the presence of fluorine (F$_2$). Even in an alloy the constituent metal atoms are either "sharing" electrons or receiving/donating electrons. Fluorine is the element with the highest known electronegativity and would "pry" the electrons from the electron-accepting metal atoms.


According to the Wikipedia article on the chemical reactivity of fluorine, fluorine (a very strong oxidizing agent) reacts with every element except helium and neon. So it looks like no metal has the property you want. The reason helium and neon are so unreactive is that their outer electron shells are completely filled, with no hidden subshell available to accept an electron. No metal (or any other element, for that matter) has this property.

  • $\begingroup$ Good answer, but what about alloys? $\endgroup$ – Cris Stringfellow Jan 3 '13 at 16:10
  • $\begingroup$ I'm less certain here, but I don't think alloying would change the chemical properties very much. It definitely changes mechanical properties (like hardness) because of the different crystalline structure of the alloy. For example, stainless steel is more corrosion-resistant because the addition of chromium allows a passivating layer of chromium oxide to form (like with aluminum on its own). So in stainless, iron borrows a chemical property from chromium, but the elements are still as they were chemically. $\endgroup$ – user467 Jan 3 '13 at 17:21
  • $\begingroup$ Okay. But anyone else can back this up or refute it? $\endgroup$ – Cris Stringfellow Jan 3 '13 at 17:32

My best guess would be a combination Pt, Ru and Ni.

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    $\begingroup$ Welcome to Chemistry SE! Try and elaborate a bit more on why you think this alloy would be inert. It would make the answer more helpful to everyone. $\endgroup$ – kaliaden Apr 14 '13 at 5:20
  • $\begingroup$ Please provide more information as @kaliaden has pointed out. Thanks! $\endgroup$ – jonsca Apr 14 '13 at 5:35
  • $\begingroup$ I figured based on the above answers, as I haven't ever done metallurgy specific experiments.Turns out I'm wrong, or I haven't found the ideal combination of those metals. Aqua regia managed to dissolve the lump I mixed. But my interest is piqued so I will keep working on this and keep you posted. $\endgroup$ – Tranquil Caprice Apr 15 '13 at 1:36

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