Talk:Nitrogen dioxide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Chemicals / Core  (Rated B-class, Mid-importance)
WikiProject icon This article is within the scope of WikiProject Chemicals, a daughter project of WikiProject Chemistry, which aims to improve Wikipedia's coverage of chemicals. To participate, help improve this article or visit the project page for details on the project.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.
Taskforce icon
This is a core article in the WikiProject Chemicals worklist.

Deadly Concentration[edit]

How much NO2 would you need in the air for it to be an immediate threat?

The article says that nitrogen dioxide is an "insidious deadly poison". Does "insidious" have some kind of meaning in terms of poison/environment control? Or is this merely excessive rhetoric? If rhetoric, then "insidious" should be excised. WpZurp 02:18, 16 Feb 2005 (UTC)

It has a most definite meaning. If you rely on warning signs to let you know you've had too much, it might kill you. It gives no warning. "Very sneaky poison" doesn't sound so scientific. Merck Index Eleventh Edition uses the word "insidious" in its description of nitrogen dioxide. If you type "nitrogen dioxide insidious" into Google, you'll find it and its equilibrium partner nitrogen tetroxide are closely associated with the word "insidious" in the safety literature. Catbar (Brian Rock) 03:24, 16 Feb 2005 (UTC)
Make that third sentence "It gives little or no warning." I've caught a whiff or two of it in the past, and you quickly know you probably don't want to breathe much of the stuff. I think one could choose to ignore it, though, but that's where the "insidious deadly poison" part comes in. Catbar (Brian Rock) 03:29, 16 Feb 2005 (UTC)
Sorry, one more time. Take a look at the phosgene article for another use of "insidious" that defines it in context. Catbar (Brian Rock) 03:40, 16 Feb 2005 (UTC)
The "insidiousness" is due to the fact that symptoms of poisoning (lung edema, that is) appear 12 - hours after one has caught a too large dose. 03:09, 21 March 2006 (UTC)

How dangerous was this?[edit]

I remember being in a high school chemistry class in about 1997. The teacher left the room and the class clown decided to mix some reagents together in a beaker. I think there was about 30mL of concentrated nitric acid, among other things. Immediately a thick red-brown gas with a pungent ozone-like odour billowed out of the beaker. He watched it for a few seconds then washed the reagents down the sink with water. Of course we were all shouting at him not to be an idiot.

We didn't evacuate and the smell lingered for quite some time. I wonder if anyone can speculate as to how much danger we were in? -- FP <talk><edits> 05:47, August 6, 2005 (UTC)

  • This is not dangerous if done under a fume hood. We did it all the time in my chemistry class. In the open room, you may have been in some considerable danger. {T-Bone 18:52, 19 October 2005 (UTC)}
    • You were not in any serious danger from the nitrogen dioxide, except maybe if it triggered an asthma attack. If that particular experiment produced a lethal dose, there would be a lot fewer chemists around than there are. The conc. nitric acid is what might have caused some real, permanent damage (happily it seems not to have done). Physchim62 01:56, 24 October 2005 (UTC)
  • This gas is very dangerous. You have to keep in mind it will create Nitric acid when it reacts with water which there is no lack of inside your lungs. 30mL isn't enough to kill everyone in the room, but if you stuck your nose inside the beaker I can bet there would be some damage done. The effect also are not instant because you mainly die from fluids cloging your lungs. -Loyal
Who ever thought of stucking one's nose inside the beaker? God, people, like you've never heard of the word "dosage". Oxygen is toxic, too. When administered pure, for some time.

Just smelling this gas at low concentrations (like after this experiment in the room) will not kill you nor induce wounds. In concentrations which make people cough, it still isn't so dangerous if you cover your mouth and nose with a piece of cloth. It is a corrosive like chlorine and ozone are. It's not specially toxic like HCN, for example.Endimion17 (talk) 14:42, 25 August 2008 (UTC)

The word "poison" should tell one that it is dangerous. Personally, I have seen brief exposure to a significantly less than 1% by volume concentration cause delayed-onset pumonary edema resulting in loss of consciousness due to hypoxia. The gas was not noticed by smell in that incident. This is not something to fool around with. Some people may be more tollerant of its vasodilation than others, but it CAN kill you at disturbingly low levels. --Rwberndt (talk) 19:42, 21 April 2011 (UTC)

Please verify the data for NO2 and N2O4[edit]

The data for NO2 and N2O4 are not very consistent in literature, probably because they always exist together in equilibrium. Verification of the data is recommended before use. R6144 14:45, 26 August 2005 (UTC)


Is Nitrogen Dioxide less dense than air?

no, NO2 is more dense by a factor of ca. 46/29.--Smokefoot 00:58, 21 March 2006 (UTC)

The article says density is "3.4 kg/m³, gas at 294.25 K" ... doesn't make sense. Should be approx. 46/29 * 1.2 kg/m3 = 1.9 kg/m3 ... ? —Preceding unsigned comment added by (talk) 08:34, 2 April 2008 (UTC)


why doesnt this molecule have a picture?



Outdoor carbon monoxide, nitrogen dioxide, and sudden infant death syndrome H Klonoff-Cohen1, P K Lam1 and A Lewis Archives of Disease in Childhood 2005;90:750-753 [2]

The San Diego guys where not the first and the link is brooken anyway. Pollution can cause it would be a better clue than NO2 alone.--Stone 06:43, 2 August 2006 (UTC)

created by a plasma?[edit]

Does anyone know if NO2 is created when a lit match under a globe is microwaved? This is the subject of an interesting MySpace clip ( and I just wondered if the gentleman performing the experiment knew what he was talking about (when he claimed that the process created NO2 ... "So don't breath it!" he said). JimScott 16:31, 8 June 2007 (UTC)

DiNitrogen Tetroxide (Nitrogen Dioxide)[edit]

--Jonnerrs 20:24, 30 August 2007 (UTC)In formulating metallic silver(Al)/Gold (Cu/Zn) inks and paints based on cellulose nitrate (NC - Gun Cotton)(disolved in esters), if there is a degree of water present, the cellulose nitrate will be partially reduced to cellulose and NO2=N204. Which becomes apparent as a reddish brown gas, with an astringent smell. I can only cite personal experience here.--Jonnerrs 20:24, 30 August 2007 (UTC)


It is grouped as a 'bleach' in the bottom. But nothing is mentioned in the article? —Preceding unsigned comment added by (talk) 09:53, 17 December 2007 (UTC)

Lewis Structures[edit]

Are these Lewis structures correct? It doesn't seem possible for NO2 to have 2 double bonds.

Kundai andrew (talk) 08:39, 3 October 2008 (UTC)

Yeah, they can't be right - 9 electrons round nitrogen.
I think the image below is the closest a Lewis structure can get to representing the bonding in NO2.
Ben (talk) 11:55, 3 October 2008 (UTC)

The Image isn't showing two double bonds, it's showing a 1.5 bond. Dotted lines mean a "half bond" or a third of a bond, it happens when there are resonance structures. Havabighed (talk) 06:07, 4 July 2012 (UTC)

These comments refer to the article as it was on 3 October 2008, when the image File:NO2-Schema-Lewis.png was included in the chembox. --Ben (talk) 00:11, 6 July 2012 (UTC)

I think it's worth revisiting this issue again. I've made File:NO2-Lewis-resonance.png, but there's also a pair of structures with the unpaired electron on oxygen and no charges. See for details. This would be a useful addition to the article if we can explain it well in the text.


--Ben (talk) 18:48, 3 June 2016 (UTC)

NO2 contributes to the formation of fine particle pollution and smog; permissible hourly and annual levels allowed by US EPA[edit]

NO2 is formed from vehicle, power plant and other industrial emissions, and contributes to the formation of fine particle pollution and smog.

Short-term exposures to NO2 have been linked to impaired lung function and increased respiratory infections, especially in people with asthma.

The EPA one-hour standard for NO2 is a level of 100 parts per billion (ppb). The annual average standard is 53 ppb.[1]!

OpenDocument —Preceding unsigned comment added by Ocdcntx (talkcontribs) 15:49, 26 January 2010 (UTC)


Is this a compound created by combustion of nitromethane with air (i.e. top fuel drag racing fuel)? I was at a drag race the other day and experienced the exhaust fumes (it's something the fans love to do, apparently). Eyes water, nose stings, throat stings, almost choking, etc.. My educated guess told me it's probably a nitrogen oxide reacting with water in eyes/mucous membranes.. Is NO2 the culprit? -- (talk) 00:29, 15 July 2010 (UTC)

Wording in the NO2-N2O4 equilibrium section[edit]

"The paramagnetic monomer is favored."

Is this some sort of joke? Even after reading the introductions to paramagnetism and monomers, I have no idea which of the two molecules is being talked about. This is supposed to be an encyclopedia, not a chemistry puzzle site. Can somebody please edit it so it's actually helpful to somebody without a PhD in chemistry? — Preceding unsigned comment added by (talk) 19:21, 3 October 2011 (UTC)

No joke. That section is talking about both. The article as a whole talks about the monomer, which predominates at standard conditions. Plasmic Physics (talk) 11:24, 4 October 2011 (UTC)

monomer = NO2, dimer = N2O4 (two molecules of NO2 bonded together). I agree the wording is probably unnecessary. Why not "NO2 is favored at higher temperatures, while at lower temperatures, dinitrogen tetroxide (N2O4) predominates. Colourless dinitrogen tetroxide (N2O4) can be obtained as a solid (melting point −11.2 °C). NO2 is paramagnetic, while N2O4 is diamagnetic." — Preceding unsigned comment added by (talk) 23:48, 13 August 2012 (UTC) Oops, this was me, forgot to log in Vultur (talk) 00:56, 14 August 2012 (UTC)

Yes, I agree this is much clearer as the molecules are identified explicitly before describing them as paramagnetic and diamagnetic. So I have gone ahead and changed the wording, almost as you have suggested. I added that the paramagnetism is due to the unpaired electron. Dirac66 (talk) 00:13, 14 August 2012 (UTC)

Material to be added[edit]

Between 2005 and 2011, the concentration of NO<sub>2</sub> across the United States greatly diminished. "The shift is the result of regulations, technology improvements and economic changes, scientists say."<ref>{{cite web|url=|title=New NASA Images Highlight U.S. Air Quality Improvement|date=26 June 2014|accessdate=15 July 2014|publisher=NASA}}</ref>

Although someone ought to reword the second sentence so as not to plagiarize and expand on some of the technical aspects. - Sweet Nightmares 01:59, 16 July 2014 (UTC)

Interesting tidbit, but Wikipedia is not a vehicle for US-oriented news. --Smokefoot (talk) 02:01, 16 July 2014 (UTC)
You're right, Wikipedia is an encyclopedia where people can learn about things, such as the fact that NO2 pollution in the US has been diminishing. - Sweet Nightmares 16:17, 16 July 2014 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Nitrogen dioxide/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

The article mentioned that Nitrogen and oxygen react at "elevated temperatures" - how high temperatures, precisely?

Last edited at 23:31, 18 June 2008 (UTC). Substituted at 01:19, 30 April 2016 (UTC)