Talk:NOx

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Distinguish from nitrous oxide
Isn't it also used as a booster in car racing? I seem to remember it from The Fast and the Furious. RickK 20:30, 2 Aug 2003 (UTC)

Is this the same as nitrous oxide? Koyaanis Qatsi 20:32, 2 Aug 2003 (UTC)

No, nitrous oxide is N2O; nitrous oxide too is the compound occasionally used by the testosterone boys where it mainly serves to throw rods and break U-joints, though a good deal of horsepower is given off before everything flies apart. I can't remember why it helps; perhaps there's enough energy in the bond between the N2 and the O to make up for the relatively lower oxidizing capacity than oxygen.

I believe that NOx is properly written NOx and is either NO2, nitrogen dioxide, or NO, nitric oxide, or any mixture of the two. NO is unstable in the atmosphere at forms NO2 through reaction with oxygen; NO2 forms nitric acid HNO3 through the reaction 2NO2 + 2H2O ==> 2HNO3 + H2 (gas). In the atmosphere, either can form Nitric acid, which eventually precipitates out in rain or snow.

Your actual mileage may vary; I didn't crack a book and a chemist is on the long list of things at User:Kat/What Kat is not. :-).. Kat 20:58, 2 Aug 2003 (UTC)


 * But, in the movie, and in a recent episode of CSI, they refered to the booster as nox, however it's spelled. Even if NOX isn't nitrous oxide, it is what they're calling the booster stuff.  RickK, even less of a chemist and only knows his science from watching movies and tv shows


 * Hmm. I'll just venture to say that if you call up Praxair or Airgas or whoever it is that you usually call when you need to get a cylinder or two of industrial gasses in your part of the world, that they will give you the telephone equivalent of a blank stare if you ask for NOx.  Kat 01:16, 3 Aug 2003 (UTC)


 * Well, the answer to why it helps boost engine performance is answered here: nitrous oxide. Ayule 01:20, 18 Mar 2005 (UTC)

N2O                dinitrogen oxide            OR                   nitrogen(I) oxide

NO                 nitrogen oxide               OR                   nitrogen(II) oxide

NO2                nitrogen dioxide            OR                   nitrogen(IV) oxide

NOx is the generic term for all oxides of nitrogen, both nitric oxide (NO) and nitrogen dioxide (NO2) &mdash; maybe others, but I don't think so. Yes, it should properly be written as NOx, which you would code in a Wikipedia page (or any HTML document) as:  NO&lt;sub>x&lt;/sub> . The subscript of course indicates how many atoms of the preceding element/symbol are in the molecule, the x naturally is a variable.

Either way, both are quite reactive in the atmosphere, because the oxygen has a valence (number of available bonds) of 2, and nitrogen has 3. As far as I know, nitric (or nitrogen, or nitrogen II) oxide molecules have a double bond between the two atoms, nitrogen dioxide (or nitrogen IV oxide) has either a triangle of single bonds (with the third nitrogen bond left open, which is what makes it reactive), or maybe more likely an NO molecule with an oxygen attached to the formerly-free nitrogen bond on one side, and itself open on the other (keeping it reactive). I know that sunlight is a catalyst for these reactions, especially on hot, stagnant, smoggy summer days.

"Nitrous" (nitrous oxide, or nitrogen I oxide, or N2O) is definitely different than the first two, used as "laughing gas" at the dentist's office (and the one time I had it, I felt like I was going to die of suffocation! ack!). It is heavier than air, which makes your voice deeper, the opposite of helium. It is also used in cars, especially in remote control model cars, to give extra "kick" to the combustion in the engine, though I don't know exactly how this works.

I made a couple of crude diagrams below, the first is NO, the last is N2O, one of the other two is NO2 (which I'm not sure of the structure of). Note the "un-terminated" bond (free radical) on the first three, which is what makes them so reactive.

O=N-     O-O \ /      O            N       / \ O=N-O-    |       N=N

(Did I just write an article?)  --Radiojon 23:11, 5 Aug 2003 (UTC)


 * Nitrogen oxide lists five oxides, only two of which fit the formula NOx. Should these articles be merged, or reference each other, or exchange pieces with each other? Also, I've come across a reference to N2O2 in Progress spacecraft, which isn't mentioned in either article. Where should that go? Bryan 20:18, 21 Feb 2004 (UTC)
 * I have resolved this one - there was a typo on the page it should be N2O4 - the actual link went to the right page. Its now fixed.--NHSavage 10:49, 14 August 2005 (UTC)


 * It seems to me that the x should be italicized (NOx), as variables normally are. Gene Nygaard 05:08, 15 Dec 2004 (UTC)

Well in atmospheric chemistry NOx always refers to the sum of NO plus NO2. The reason for this is that during daylight in the troposphere they are involved in a rapid cycle which quickly reaches a steady state.

NO+O3 → NO2 + O2

NO2+ photon → NO + O

O + O2 → O3

Because these 2 compounds are so closely connected it is often useful to look at their sum.

I suspect that we need to differentiate between this use and the scientifically flawed but widspread (?) use of this term for Nitrous OXide. Perhaps NOX is nitrous oxide while NOx is NO+NO2 ? I think probably the whole heirarchy needs some work as their are several pages for different case combinations and the disambiuation should include all then redirect properly. Some of the chemistry from this thread should go in somewhere as well.

Tropospheric ozone is produced when NO reacts with peroxy radicals to give NO2.

User:NHSavage 17:27, 10 Aug 2005 (UTC)

I have now merged the 2 disambiguation pages and refered to the use of the phrase NOx for nitrous oxide there.--NHSavage 10:37, 14 August 2005 (UTC)


 * Presumably it is called NOx because it is NOxious? Anthony Appleyard (talk) 15:49, 3 October 2013 (UTC)

NOx is used by atmopsheric scientists to refer to odd nitrogens and includes several compounds including N2O5 There is a section on NOx in the textbook Aeronomy of the Middle Atmosphere (ref>Guy P. Brasseur and Susan Solomon, 1984 .  A thumbnail of the story is presented on slide 28 of this grad class lecture slide set: http://www.atmos.umd.edu/~russ/637LstratO3.ppt . All of these are implicated in the ozone cycle which is why it is problematic for ground based emission (increases ozone in the presence of UV which is hard on the lungs) and also, as already noted, can catalyze the destruction of ozone in the troposphere where it is wanted. OriEri 00:01, 22 September 2015


 * This is definitely a minor use of NOx. Even on the slides you linked to, it says "This total of “odd nitrogen” is better called “NOy”"

In the fuel combustion world, NOx refers to NO + NO2, not because of some rigid scientific rule, but simply because those are the nitrogen/oxygen species produced in combustion devices. Usually the subscript is not included, but strictly speaking it should be there to denote a chemical formula subscript (x = 1 or 2). That doesn't mean nitrous oxide, N2O, cannot be produced in combustion. Clearly it would be in a poorly controlled flame like a wildfire, or maybe even in a fireplace, where there is not thorough mixing of oxygen with the fuel. But that is not the case in most industrial combustion, where thorough oxidation of the fuel is crucial to efficiency and pollution control. So N2O is typically not considered to be a component of NOx and typically very small (probably about 100X lower in concentration) than NO and NO2.

Rick Knight — Preceding unsigned comment added by 73.50.12.218 (talk) 05:01, 28 February 2016 (UTC)

Global cooling
Greenhouse gas and Nitrous oxide contradict the assertion in NOx that NOx is a global coolant. The US EPA says NOx is one of the main greenhouse gasses, and doesn't mention any cooling effect. A single source the OECD, supports the claim that NOx reduces methane, but this isn't mentioned elsewhere. These three articles should be brought into agreement. --Dennis Bratland (talk) 00:19, 20 September 2015 (UTC)


 * There's no contradiction. As the article says, NOx refers to NO and NO2 -- notice this doesn't include N2O. This definition follows the scientific and engineering literature which distinguishes between NOx and N2O, e.g., this article amongst many. So it's consistent to say that NO and NO2 (i.e., NOx) have a cooling effect while N2O (i.e., not-NOx) has a warming effect. Short Brigade Harvester Boris (talk) 01:11, 20 September 2015 (UTC)
 * There is a contradiction and I think it involves a much larger number of articles. Here is a partial list of articles that link here in reference to pollution from combustion:
 * Catalytic converter
 * Snowmobile
 * Diesel locomotive
 * Honda Insight
 * Alternative fuel
 * Vehicle emissions control
 * Volkswagen
 * etc...
 * I get the fact that engines emit a variety of compounds, some of which are greenhouse gases and some of which aren't. But we have a situation where several related Wikipedia article fail to fully explain this, and instead operate in a siloed fashion, explaining only what is strictly within the article scope and ignoring the context. It gives the false impression that, for example, 3-way catalytic converters are making global warming worse by reducing beneficial NOx. Often this is due to imprecise language by mainstream media sources. That's not Wikipedia's fault but it's still a problem we are capable of addressing if we rewrite the related articles to underscore the important distinctions.I don't know if there needs to be a wider RfC on this, or if I just need to make the contradiction tag include every one of the above articles. For now I'd like to leave the contradiction tag in place to see what solutions can be proposed. --Dennis Bratland (talk) 00:30, 21 September 2015 (UTC)
 * An RfC would be good, because I simply fail to understand why you think there is a contradiction. To me it's a simple case of A and B being two different things that act differently (where A=NOx and B=N2O). Short Brigade Harvester Boris (talk) 00:41, 21 September 2015 (UTC)
 * Here is a specific example, from Vehicle emissions control:
 * "Nitrogen oxides (NOx) - Generated when nitrogen in the air reacts with oxygen at the high temperature and pressure inside the engine. NOx is a precursor to smog and acid rain. NOx is a mixture of NO, N2O, and NO2. " It links to Nitrogen oxides but uses the formula NOx, which is NOx not Nitrogen oxide. NOx is only NO and NO2, Vehicle emissions control is also including N2O, and NO2 -- Nitrous oxide? --Dennis Bratland (talk) 01:50, 21 September 2015 (UTC)
 * Yeah, somebody screwed up there. Including N2O as part of NOx would seem reasonable to someone who is writing things off the top of their head (since it's an "oxide of nitrogen") but it's not correct. As the EPA says, "The sum of nitric oxide (NO) and NO2 is commonly called nitrogen oxides or NOx." Short Brigade Harvester Boris (talk) 03:11, 21 September 2015 (UTC)
 * This and this say that NOx is a family of 7 compounds, only two of which are regulated by the EPA. Are we making the mistake of saying NOx is only NO and NO2 because of the regulation of those two, when in fact NOx also refers to five others, N2O2, N2O3, N2O4, N2O4, and -- wait for it -- N2O?!. --Dennis Bratland (talk) 17:56, 22 September 2015 (UTC)
 * Seems some sources (Diane Pub. Co. - reliable?) do seem to confuse the issue. But the usage most common follows from the subscript (x) in NOx is a variable for the oxygen of the formula. Using it for N2O seems quite illogical - should be NxOy to cover those. So perhaps a note noting that apparent misuse/confusion would be appropriate. Vsmith (talk) 14:43, 21 October 2015 (UTC)
 * It is the nomenclature used in the preponderance of reliable sources that is relevant, and not any WP editor's perspective of what seems to them as interpretatively logical or illogical. If a number of reliable sources describe N2O as an NOx, that is what matters. As for the logic or illogic, Vsmiths argument presumes that x is an integer, and there are ample areas of chemical nomenclature where non-integer values of subscripts are used in formulae. Hence, again: What is the usage in the sources? Le Prof  73.210.154.39 (talk) 20:49, 21 December 2015 (UTC)
 * I still don't see how you've decided which sources are correct. But even if you know which ones are right, these articles need to explain it. Just ignoring it leaves readers confused when we should be helping them understand. The US EPA gives conflicting statements on whether NOx includes N2O or not. The basic question of whether nitrogen-related pollution from diesel engines is a greenhouse gas or not is totally muddled. We need to either explain it, or else describe the controversy. The status quo is to ignore the whole issue. --Dennis Bratland (talk) 15:57, 21 October 2015 (UTC)
 * How about this EPA Technical Bulletin then? . Table 1 indicates that NOx (nitrogen oxides) refers to: N2O, NO, N2O2, N2O3, NO2, N2O4 and N2O5... --200.223.199.146 (talk) 12:31, 20 January 2017 (UTC)

Magical disappearing oxygen?
The following equation appears in the section "NO from N2O":
 * N2O + O → NO + N   (thermal NO)

This plainly can't be right. Two nitrogens and two oxygens can't make two nitrogens and one oxygen, not without magic or nuclear annihilation. Moreover, the reference to "thermal NO" suggests that this should be an equation listed higher up in the article that yields the same products:
 * N2 + O → NO + N

But if this is the correct reaction, then it doesn't belong in a section titled "NO from N2O" at all! Can someone with the appropriate subject knowledge clear this up? --Perey (talk) 12:46, 22 June 2016 (UTC)
 * , I removed now the section with equations. "No sources. contested on the talk page for more than 6 months.".--200.223.199.146 (talk) 11:57, 20 January 2017 (UTC)

Hardly any role in air pollution
currently the article reads "Nitrous oxide plays hardly any role in air pollution..." in its introduction blurb. Should there not be a reference for this and, more importntly, why is Nitrous oxide discussed in the blurb for NOx in general? Surely this sentence should be moved to a later section rlating only to nitrous oxide, otherwise it might cause some confusion, i beleive — Preceding unsigned comment added by 91.176.193.191 (talk) 12:04, 15 March 2017 (UTC)

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Half height or subscript or both, for the X
What is the typical typography in the literature for the X in NOX? To capture both NO1 [sic] and NO2, I could imagine using a half-height x (NOx), a subscripted full-height X, (NOX), or an X is that both half-height and subscripted (NOx). What do the scientists use? 64.132.59.226 (talk) 14:59, 22 February 2018 (UTC)
 * Just use  to get . Also see IUPAC nomenclature of inorganic chemistry —Dennis Bratland (talk) 16:34, 22 February 2018 (UTC)
 * I don't find any mention of the proper typography of NOX in the Wikipedia articles IUPAC nomenclature of inorganic chemistry and IUPAC nomenclature of inorganic chemistry 2005. For instance, knowing that the dioxide is NO2 does not indicate to me whether a subscripted X for NOX should be full height (X) or half height (x).  What is the evidence that the current implementation of the   template is correct?  64.132.59.226 (talk) 17:59, 22 February 2018 (UTC)
 * The EPA uses NOx with a lower case x that is not in italics. Is that the proper standard rather than the  with italics?  64.132.59.226 (talk) 18:32, 22 February 2018 (UTC)
 * "Proper" isn't really a thing. The IUPAC rules are at ; if you work for the EPA I suppose they publish their own manual of style somewhere. On Wikipedia the best choice is almost always to use templates like CO2 or NOx or Convert because the template is always going to spit out whatever the general consensus is among editors. If they decide to change the x to half height instead of subscript or italic or whatever, it will change on every single article that uses the template, rather than having to track down each instance and bring it up to date. If the template is wrong, then the place to raise the issue is at Template talk:NOx or at Wikipedia talk:WikiProject Chemistry so that it will be fixed everywhere and not just one article. --Dennis Bratland (talk) 20:16, 22 February 2018 (UTC)


 * I use subscript :: NOx is NOxious. Anthony Appleyard (talk) 05:43, 8 March 2019 (UTC)
 * NO2 and its relatives are almost universally written with the number as a subscript. In the few places that don't it is because that place doesn't support subscripts (eg in plain text with no formatting available). Therefore it makes sense for to also use subscripts. The explanation by Dennis for using templates like  is exactly what I was thinking of when I created it 5 years ago - only one place needs to be updated if consensus changes. I originally created it using CSS to simulate the subscript so that I could make it hug the NO a bit closer and make less of an effect on the spacing between that line and the next (subscripts increase the spacing a little). It got changed to a plain subscript about 2 years but I was too busy to challenging it at the time.   Stepho  talk  09:48, 8 March 2019 (UTC)

Definition of
In the introduction, the article states that in Atmospheric chemistry, means NO + NO₂. Then it says that in Chemistry, is any of a much larger set of molecules and radicals. The article then goes on to cover NO and NO₂ exclusively, and implicitly refers to N₂O as a non-.

I think the introduction could be clearer on this point, explaining the "conflict" between the general chemistry and atmospheric chemistry usage of the term, and then stating explicitly that this article only considers the narrower atmospheric understanding of. Kjetilho (talk) 14:17, 1 March 2020 (UTC)

Warming effect
The text currently says, "In conclusion, considering several direct and indirect effects, emissions have a negative contribution to global warming.[32]". Is this good or bad? It is not at all clear. Reference 32 is to IPCC 2013, which was behind a paywall for me, but I found a copy on their web page.

""In addition, carbon monoxide emissions are virtually certain to cause a positive forcing, while emissions of reactive nitrogen oxides likely cause a net negative forcing but uncertainties are large. Emissions of ozone-depleting halocarbons very likely cause a net positive forcing as their direct radiative effect is larger than the impact of the stratospheric ozone depletion that they induce. Emissions of SO2, organic carbon and ammonia cause a negative forcing, while emissions of black carbon lead to positive forcing via aerosol–radiation interactions.""

Clear as mud for a lay-person like me, but from the context I can tell that negative forcing is good.

My suggested edit: "In conclusion, considering several direct and indirect effects,  emissions likely contribute to reduce global warming." Kjetilho (talk) 14:46, 1 March 2020 (UTC)

Prompt
In the 'prompt' section, it doesn't say why it is called prompt NOx. Does anybody know what it stands for?  Stepho  talk 10:45, 8 April 2020 (UTC)