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Author: Subject: Nitric acid properties
tom haggen
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Nitric acid properties

What is the lowest concentration that nitric acid will fume at? Also, what is it about nitric acid that makes it smell somewhat like chlorine?

[Edited on 27-4-2004 by tom haggen]

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The_Davster
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Smells like chlorine? My nitric acid(70% reagent ACS grade) the fumes smell nothing like chlorine, they smell like...well I cant really describe it just burns. Is your nitric home prepared? It could be contaminants causing the smell.
BromicAcid
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Mine is also reagent 70% grade and on occasion it seems like there is a waft that has similar smell characteristics to chlorine. I believe this is from the airborn acid hydrolyzing in your nose, not from the acid smell itself.

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tom haggen
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When I first bottled my freshly distilled Nitric acid, it was about the color of an uncharged glow in the dark sticker. After a few hours, yellowish orangish fumes build up in the bottle, and my acid turns bright yellow. I was using PVDF for a gasket, and that was the same material I was using during the distillation with no significant corrosion. Is my nitric acid still reacting with the PVDF anyway? I'm planning on making a gasket out of teflon tape as soon as I can afford some. Finding a proper container for storing nitric acid has proven to be a difficult task for me. Oh and by the way, if my HNO3 is reacting with my PVDF gasket, will I still be able to use it for nitrations?

[Edited on 28-4-2004 by tom haggen]

Ok, I just read on this site that nitric acid can be light sensitive. I did have my HNO3 sitting in a window cill today, mabey thats what happened? Should I pitch my nitric acid???

[Edited on 28-4-2004 by tom haggen]

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fvcked
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Your nitric did most likely decompose from the light, what material is the container body? And I think that an empty and properly cleaned wine bottle would be a suitable contaner, if you could find a stopper for it. Make sure though that you use a container that doesnt let much light get through. And as for pitching your nitric: IMHO, you could probably use it soon for a few synths, but I wouldnt try to store it for too long.
Cyrus
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A suitable material for a wine bottle
might be a wine bottle cork

Just wrap it in teflon tape very very thouroughly. The teflon layers will conform and stick to each other very well, and to the bottle.
acx01b
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hno3 smells a little like when zn reacts with h+, and a little like chlorine...

its my opinion! ;-)
Esplosivo
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 Quote: hno3 smells a little like when zn reacts with h+, and a little like chlorine...

And what's that smell supposed to be like. Doesn't Zn reacting with H+ give off Hydrogen. Hydrogen?!

I too have reagent grade 70% nitric acid and sometimes it does smell something pungent similar to chlorine. Most probably receptors on the nose cannot distinguish between two gasses acidic in nature and just gives the sense of irritation.

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Mumbles
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I've noticed that Nitrogen Dioxide and Chlorine smell rather similar. I don't know if it's from the burning, or what. It's probably decomposing into NO2/N2O4 and that is what smells like chlorine. Nitric Acid itself doen't have much of a smell, just a general burning/irritation.
acx01b
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chlorine burns too!!

(try to make zn reacting with h2so4 you'll smell new odors very different of h2so4's ones, and not exactly the sames as an naoh/water electrolysis....)

[Edited on 13-5-2004 by acx01b]
frogfot
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Can't it be sensor overload (in the nose) that gives very stinky things same smell? Sometimes when one takes a deep breath of fresh air, it smells a bit like chlorine to..
Esplosivo
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 Quote: Sometimes when one takes a deep breath of fresh air, it smells a bit like chlorine to..

Coul be some ozone in the atmosphere. Especially in places where photochemical smog is common ozone is in quite high concentrations. Ozone has a smell which is sort of chlorine.

Abou the zinc reacting with the H2SO4. I think this depends greatly on the purity of both the acid and/or the zinc metal used. Impurities might lead to different smell because of the production of other volatile products. What concentration of the H2SO4 do you use? High concentrations might give off SO2 when reacting with metals, but there is quite a difference between the smell of SO2 and that of Chlorine.

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blip
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 Quote: I've noticed that Nitrogen Dioxide and Chlorine smell rather similar. I don't know if it's from the burning, or what. It's probably decomposing into NO2/N2O4 and that is what smells like chlorine. Nitric Acid itself doen't have much of a smell, just a general burning/irritation.

Back in chem class my teacher made some NO<sub>2</sub> in the fumehood as a by-product of Cu(NO<sub>3</sub><sub>2</sub> production and allowed us to smell it. I found it much more irritating than anyone else, apparently, considering that I had to move to the back of the group from somewhere in the middle. Anyway, to the point, I found that NO<sub>2</sub> has much more of a metallic smell to it but also irritating and kind of bitter in a way. Chlorine burns and irritates but it feels more like needles poking me.

fvcked
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Unfortuneatly, or fortuneatly depending on how you look at it, I got introduced to chlorine by accidentally filling my lab with it. I was introduced to NO2 first, and in my sincere opinion the chlorine was the worst! It burns even after your in fresh air, and after youve washed your eyes out, although it does burn less. Neither was a pleasureable experience but both were a nescessity. One needs to have accidents with some things before he/she fully realises and understands the danger of chemistry. Luckily most of us have relatively harmless accidents.
tom haggen
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Well, I finally got my meat hooks on some beautiful clear reagent grade 70% nitric acid. Only I stored it improperly and it became a tinted light yellow color
The acid vapors must have seeped through the seams in the teflon tape that I wrapped around a rubber gasket. Oh well, The gastket only corroded for like 2 days so I think that my acid is still worthy of doing some simple nitrations.

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The_Davster
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I believe it becomes tinted yellow when exposed to light. I keep my reagent grade nitric in a box full of packing peanuts and the box in a black garbage bag. I guess this is a bit over protective, but it cost me 50$for 500mL. Esplosivo National Hazard Posts: 491 Registered: 7-2-2004 Location: Mediterranean Member Is Offline Mood: Quantized  Quote: it cost me 50$ for 500mL.

Woww. Is that a normal GPR grade reagent?! Or is it a sort of analytical grade? Is seems quite too costy. Where I live I bought 2.5L for less than half the price, though I know prices vary.

Theory guides, experiment decides.
tom haggen
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Yes light does turn nitric acid. However, my acid has turned yellow from reacting with a gasket like I mentioned in my previous post. luckly it was cheap, I got it from a friend but I had to provide the container. Thats why it was stored improperly in the first place. Could anyone explain exactly whats happening when nitric acid turns from clear to yellow. Is it because of an increase of NO2 or is it simply from some sort of decomposition or both?

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The_Davster
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Explosivo: It was low grade analytical, I have seen some super anlytical grades for over 200\$ for 500mL. Of course I never bought any of these.
Mumbles
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Basically UV rays decompose the nitric acid into water, NO2 and something else(O2 or N2 maybe). The NO2 stays dissolves and discolors it yellow. Adding a bit of urea will remove any yellowing.

I've also heard of light serving as a catalyst for self decomposition.

2 NO<sub>3</sub>- + 8 H<sup>+</sup> ---> NO<sub>2</sub> + 4 H<sub>2</sub>O + 1/2 N<sub>2</sub>

That is from memory so it is probably wrong but similar to a real one.

[Edited on 6-8-2004 by Mumbles]
The_Davster
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Why dont they sell nitric acid in the brown glass bottles then?
BromicAcid
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Hmmm... I really don't know why they don't sell it in brown bottles. I was doing some dissolving of bismuth with it the other day and I left a beaker full of HNO3/HCl with Bi in it covered by a watch glass on the table and a bulb type 10 ml pipette. The day was of course sunny and when I came back everything was gold! The HNO3 in the pipette decomposed and filled it with an unreal golden hue and the beaker was filled with the same dilute NO2 mixture, very beautiful. I left a gallon sitting in the sun for 10 minutes or so and it readily turned greenish. Really though, a little NO2 in your HNO3 is nothing to worry about, just look at red fuming nitric acid, it had NO2 concentrated into it.

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Esplosivo
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 Quote: Originally posted by rogue chemist Why dont they sell nitric acid in the brown glass bottles then?

Well actually mine is in a brown opaque container, and its just a GPR grade, not analytical. This acid is from 'BDH Lab Supplies' and is of 69% conc.

Theory guides, experiment decides.
tom haggen
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I used my 70% yellow nitric acid the other day in a synthesis and I got horrible yields. On top of that my nitro is completely yellow, it looks disgusting. I think that my nitric acid was more decomposed than I first anticipated. Oh well, I start working for a pyrotech tomorrow so i'm sure I can just get some analytical grade HNO3 from him.

[Edited on 9-6-2004 by tom haggen]

[Edited on 9-6-2004 by tom haggen]

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Magpie
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Tom Haggen,

Congratulations on your new job! Just think, you will now be getting paid for what you would do for free, right?

The single most important condition for a successful synthesis is good mixing - Nicodem

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