Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Adstar on 27/01/2011 15:09:37

Title: What colour are nitric and nitrous acids?
Post by: Adstar on 27/01/2011 15:09:37

Hello all.  [8D]

I am new to this forum; I have joined looking for an answer to a Question. I was going to post this in the questions needing answers section of your forum but it seems i do not have posting rights in that area yet. So i am posting here hoping that someone is either knowledgeable in the area of meteor impact effects or chemistry.

Ok on to the question.

I have been reading a paper on the effects of a meteor impact upon earth part of the paper states and i quote:

Quote sourced from:
 

http://www.astronomynotes.com/solfluf/s5.htm (http://www.astronomynotes.com/solfluf/s5.htm)

Quote

The heat from the shock wave of the entering asteroid and reprocessing of the air close to the impact produces nitric and nitrous acids over the next few months to one year. The chemical reaction chain is:

   1. N2 + O2 ‚> NO (molecular nitrogen combined with molecular oxygen produces nitrogen monoxide)
   2. 2NO + O2 ‚> 2NO2 (two nitrogen monoxide molecules combined with one oxygen molecule produces two nitrogen dioxide molecules)
   3. NO2 is converted to nitric and nitrous acids when it is mixed with water.

These are really nasty acids. They will wash out of the air when it rains---a worldwide deluge of acid rain with damaging effects:

So my question is what colour would this rain be?

What colour does water turn when it is mixed with nitric and nitrous acids?


Thanks for any help you can offer.

Title: Re: What colour are nitric and nitrous acids?
Post by: rosy on 27/01/2011 15:26:25

Nitric acid is colourless, nitrous acid is pale blue, but I doubt that would be noticable at the likely dilutions in rain.

On a housekeeping related note, if you're posting a question, please could you put a proper question in the title bar so everyone can get an idea of your topic (and because new questions appear on the website frontpage and "?" looks pretty daft). I'll put something in there, but if you want to change it to something else you can do it by editing your original post.

You can't post on the "Questions that need answers" board because it's an automatically generated set of questions that have been up for a while and not been answered, so no-one can post directly to it.
 

Title: ?
Post by: CliffordK on 27/01/2011 15:52:47

Can we please add a title.

The link above is "authentic" & does lead to pertinent docs.

Here is the EM/IR Spectrum of Nitrous Oxide (N₂O) (among other atmospheric substances).

http://en.wikipedia.org/wiki/Greenhouse_gas
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F7%2F7c%2FAtmospheric_Transmission.png&hash=f0df5813b3bd8fbd87f8666b51e00407)

You the primary EM Absorption peaks are in the IR range (thus, transparent in visible light).

Most of the peaks also fall under CO₂ and water, thus it may not have a large additional greenhouse gas contribution. 

You are right that there are several nitrogen oxides (often abbreviated as NOx), as well as aqueous mixes forming in the clouds so this spectrum is probably an oversimplification, but it will put you on the right track to finding the information you need.

The earth gets pelted by a few small meteorites a day, perhaps many "micro-meteorites".  However, the contribution to earth's atmosphere should be more or less constant, at least over the long term.  A large meteorite impact would likely have more local nitrogen oxide formation, and perhaps no more than a couple of shuttle landings.  The dust and particulate matter would have much greater impact.

Most reports indicate that Nitrogen Oxides are important in the formation of ozone, although a couple suggest ozone depletion.

Title: What colour are nitric and nitrous acids?
Post by: Bored chemist on 27/01/2011 19:18:39

If there were enough  nitrous acid in the rain for you to see the colour, it wouldn't be troubling you for long.

Incidentally, the picture of the IR spectrum of nitrous oxide doesn't help much.
It's the only oxide of nitrogen that isn't involved in the reactions in the OP.
People might wonder why you have posted something about the wrong bit of the spectrum of the wrong compound.

Title: What colour are nitric and nitrous acids?
Post by: CliffordK on 27/01/2011 20:35:11

Quote from: Bored chemist on 27/01/2011 19:18:39

People might wonder why you have posted something about the wrong bit of the spectrum of the wrong compound.

The spectrum posted has UV, Visible, & IR Spectra. 

Sorry...  there are many Nitrogen Oxides. 
I'm probably a bit dyslexic with the differences between N₂O and NO₂   [xx(]

Title: What colour are nitric and nitrous acids?
Post by: Adstar on 28/01/2011 01:01:31

Hello Again.

Thank you all for your replies. And apologies for failing to put a heading on my thread. Thanks to the person who corrected that mistake.

From the replies it seems to me that the answer i am receiving is that in itself the acids would not cause any noticeable coluoration to the rain. I assume that the colour would be determined by other factors like meteor composition and the nature of the surface of the earth it impacted.

I have been looking up acid rain in general over the net and i have read in two places that it been experianced as a red colour. Anyway i will look at your link CliffordK thank you for providing it.  [:)]

Title: What colour are nitric and nitrous acids?
Post by: CliffordK on 28/01/2011 01:51:31

Red?

Sounds like sunsets.

Here is a note on SMOG which may be related (unfortunately only an abstract).

On the color of the Los Angeles SMOG
R.B. Husara and W.H. Whiteb
Air Pollution Research Laboratory, Department of Mechanical Engineering, Washington University, St. Louis, MI 63130, U.S.A.
Meteorology Research, Inc., 464 W. Woodbury Rd., Altadena, CA 91001, U.S.A.
Received 8 August 1973;
revised 15 July 1975.

Abstract

The origin of the yellow-brown coloration of the Los Angeles smog layer was investigated theoretically by solving the radiation transfer equation for an optically thin (in vertical direction) scattering and absorbing haze layer. Using the available data on NO₂ absorption and smog aerosol size spectra, it was found that in addition to the NO₂ absorption and aerosol scattering, the angle between the observer's line of sight and the sun plays an important role in the coloration of the smog layer and it also determines the relative importance of NO₂ and aerosol. (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B757C-48C7D9W-KX&_user=10&_coverDate=12%2F31%2F1976&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1622453537&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=04857433d6ec5c75bbc92e909822c244&searchtype=a)

You can get dynamic colors of sunsets with heavy smog.

Title: What colour are nitric and nitrous acids?
Post by: Bored chemist on 28/01/2011 06:49:12

http://en.wikipedia.org/wiki/Blood_rain
is not the same as
http://en.wikipedia.org/wiki/Acid_rain

Title: What colour are nitric and nitrous acids?
Post by: lightarrow on 28/01/2011 11:28:50

Quote from: Adstar on 27/01/2011 15:09:37

So my question is what colour would this rain be?
What colour does water turn when it is mixed with nitric and nitrous acids?

As already written, the rain wouldn't chenge its colour very much, with NO₂ dissolved in it, unless it would be concentrated acid. Concentrated acids can instead contain as dissolved, so much brick-red NO₂ to become orange-like colored.