Imran
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Nitric dioxide
Can nitric dioxide react with iron? Any help would be appreciated.
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woelen
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it can react with iron, but only in the presence of water or some other solvents, or at elevated temperature. With water, NO2 forms nitric acid and
nitrous acid, and these react with the metal. Dry NO2 in gaseous form probably does not react with clean dry iron, except at elevated temperature,
where the NO2 can oxidize the metal to an oxide and the NO2 itself is converted to NO or even N2.
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triplepoint
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It can react with iron (III) cyanide complexes. See citation http://www.sciencedirect.com/science/article/pii/S0020169300... I don't know whether this is helpful.
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Imran
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Woelen thank you for helpful answer. Kudos to you  Stainless steel is probably
only metal that can withstand those fumes at elevated temperature ;(
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woelen
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But keep in mind, that if the fumes contain water as well, that they are much more corrosive and then stainless steel also is corroded. Some metals
can be even more resistant, due to the effect of passivation. Iron also is passivated to some extent and iron, treated with a solution of a chromate
or dichromate is even more passivated. IIRC aluminium also can be passivated.
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Imran
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whoa..you are saying that iron can be pasivated with chromates so it can withstand NO2 fumes with water vapours (nitric acid) at elevated
temperatures? Please tell me more. I am all ears
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woelen
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Certain metals can be passivated so much that they withstand nitric acid at elevated temperatures. IIRC certain alloys of iron are among them. You
will have to do some research on this subject, but yes, metals which normally are easily corroded can be made much more resistant to corrosion that
even stuff like nitric acid can be handled in these metals. In industry where HNO3 is made, this is not made in nice glass vessels. I'm quite sure
that metal vessels are used and these are not made of platinum or gold 
I do not know the precise details, but use Google to find info on passivation of metals in combination with nitric acid and chromate/dichromates.
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Imran
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Thanks for info
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Pyro
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oh yes it does! i screwed up the extractor fan in my lab wit NO2, it went all rust-like. took me hours to clean off.
and it was stainless steel.
[Edited on 22-8-2012 by Pyro]
all above information is intellectual property of Pyro.  |
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AndersHoveland
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The gas can be corrosive to iron if there is moisture/water.
I do not think the reaction rate would be very fast, but my guess is that the reaction would probably look like this:
Fe + 3 NO2 --> Fe[+2] + NO3[-] + NO2[-] + NO
2 Fe[+2] + 4 NO2 --> 2 Fe[+3] + 2 NO3[-] + 2 NO
[Edited on 22-8-2012 by AndersHoveland]
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