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Syn the Sizer
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Good point, I have never dealt with 99% HNO3.
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Chemorg42
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Would fuming nitric (small amount of water) be less or more hazardous than pure nitric (no water at all?)
Anyone who is not shocked by quantum theory has not understood a single word. (attributed to Niels Bohr)
I think I can safely say that nobody understands quantum mechanics. (Richard Feynman)
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Bedlasky
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I never heard about 100% HNO3. White fuming nitric acid can exist in concentrations up to 99%, but it never be 100%. But it's less reactive than red
fuming nitric acid which contain lots of NO2.
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Syn the Sizer
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Also doesn't nitric acid and most other acids react more when a small amount of water is present? So 99% white fuming acid is less reactive than 99%
white fuming nitric acid that has been diluted slightly?
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Chemorg42
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Both of you, yes, I was mistaken. I new I had read something about water and fuming nitric acid, but I couldn't remember what.
So my new question is, which is more corrosive, red or white fuming nitric acid?
Anyone who is not shocked by quantum theory has not understood a single word. (attributed to Niels Bohr)
I think I can safely say that nobody understands quantum mechanics. (Richard Feynman)
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Syn the Sizer
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Quote: Originally posted by Chemorg42  | Both of you, yes, I was mistaken. I new I had read something about water and fuming nitric acid, but I couldn't remember what.
So my new question is, which is more corrosive, red or white fuming nitric acid? |
I could not say for certain. But I believe red would be more corrosive due to the dissolved NO2(g).
[Edited on 13-6-2020 by Syn the Sizer]
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Tellurium
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| Quote: Originally posted by Syn the Sizer | | Also doesn't nitric acid and most other acids react more when a small amount of water is present? So 99% white fuming acid is less reactive than 99%
white fuming nitric acid that has been diluted slightly? |
Well yes it doesn't attacks stuff that good when pure, because for example metals get a passivation layer.
But I think fuming nitric acid is much much worse on skin, because it is such an extremely strong oxidizer! I mean just look what happens with gloves
when putting azeotropic or fuming nitric acid on them. The glove with the fuming nitric will start to burn violently and the glove with the azeotropic
nitric acid doesn't 
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Bedlasky
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Chemorg42: As Syn the Sizer said, red fuming nitric acid is more corrosive fue to dissolved NO2.
Tellurium: I tried dissolve copper wire and molybdenum powder in white fuming nitric acid and they are attacked only little bit. There was some NO2
formation, but only small amount. WFNA passivated these metals. But when I added small amount of water, vigorous reaction with cloudes of NO2 took
place.
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Tellurium
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| Quote: Originally posted by Bedlasky | | Tellurium: I tried dissolve copper wire and molybdenum powder in white fuming nitric acid and they are attacked only little bit. There was some NO2
formation, but only small amount. WFNA passivated these metals. But when I added small amount of water, vigorous reaction with cloudes of NO2 took
place. |
Yes, thats exactly the passivation, that I'm talking about! This is caused by strong oxidizing properties, but I guess on skin exactly these oxidizing
properties are the problem
[Edited on 15-6-2020 by Tellurium]
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Bedlasky
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Yes, they are  . As I said before, it burns like a hell.
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RogueRose
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A little tip for dealing with H2O2 burns is to use hot water on the burn and I press on it with my fingernail. It seems to reduce the pain a bit and
it can make the white "burn mark" (which I think it just tiny O2 bubbles under the skin) disappear much faster, I think it's b/c it speeds up blood
flow to the area. It also does reduce the pain level a bit and I've never really gotten the same effect with cold water. My experience is with 35%
and I too think it has a much faster reaction to skin than any acids (at least room temp acids).
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chornedsnorkack
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| Quote: Originally posted by Bedlasky | | I never heard about 100% HNO3. White fuming nitric acid can exist in concentrations up to 99%, but it never be 100%. But it's less reactive than red
fuming nitric acid which contain lots of NO2. |
100 % HNO3 is quite possible, but not very popular. You can quite easily have "over 100 %" HNO3, in the sense of N2O5 rather than N2O4 dissolved in
HNO3. This type of "nitric acid oleum" is one popular nitrating agent - more stable than pure N2O5 or N2O5 dissolved in nonpolar solvents, and better
nitrating agent than 99 % HNO3. Often, it also contains phosphoric acid when it is produced simply by partially dehydrating nitric acid with P4O10 and
phosphoric acid not separated. But you can produce clean HNO3/N2O5 solution as well.
As for precisely 100 % HNO3, note that 100 % crystals are the freezing point maximum, somewhere about -41,6...41,8 %. On slow freezing of near 100 %
nitric acid, the growth of crystals would reject any dissolved H2O, N2O4 or N2O5 impurities into the mother liquor. Solid nitric acid, unlike all
liquid forms, is reasonably stable to spontaneous decomposition. Which means you could store nitric acid as a solid and thaw as needed.
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Bedlasky
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| Quote: Originally posted by chornedsnorkack | | Quote: Originally posted by Bedlasky | | I never heard about 100% HNO3. White fuming nitric acid can exist in concentrations up to 99%, but it never be 100%. But it's less reactive than red
fuming nitric acid which contain lots of NO2. |
100 % HNO3 is quite possible, but not very popular. You can quite easily have "over 100 %" HNO3, in the sense of N2O5 rather than N2O4 dissolved in
HNO3. This type of "nitric acid oleum" is one popular nitrating agent - more stable than pure N2O5 or N2O5 dissolved in nonpolar solvents, and better
nitrating agent than 99 % HNO3. Often, it also contains phosphoric acid when it is produced simply by partially dehydrating nitric acid with P4O10 and
phosphoric acid not separated. But you can produce clean HNO3/N2O5 solution as well.
As for precisely 100 % HNO3, note that 100 % crystals are the freezing point maximum, somewhere about -41,6...41,8 %. On slow freezing of near 100 %
nitric acid, the growth of crystals would reject any dissolved H2O, N2O4 or N2O5 impurities into the mother liquor. Solid nitric acid, unlike all
liquid forms, is reasonably stable to spontaneous decomposition. Which means you could store nitric acid as a solid and thaw as needed.
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That's really interesting! I never heard about this HNO3/N2O5 mixtures.
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