Sciencemadness Discussion Board - Usability of Atmospheric Nitrogen

Usability of Atmospheric Nitrogen

DDTea - 3-3-2003 at 15:24

It is a well-known fact that the air we breathe is mostly Nitrogen. However, every time, on various forums, that I've seen someone bring up the idea of using Atmospheric Nitrogen in a synthesis, it is always shot down, and rarely with an explanation (Actually, I've never seen an explanation). What is wrong with using Atmospheric N2?

I'm interested in the idea of an HCN generator (Not MAKING one, but designing one) that passes electricity through a mixture of Acetylene and Nitrogen, and then condenses the resulting HCN. I don't know of a source of OTC Nitrogen, but the most reliable source I can think of is air... Can someone explain to me why this would not work?

madscientist - 3-3-2003 at 15:59

The problem has to do with the extremely strong nitrogen-nitrogen triple bond in the diatomic N2 molecules. Extreme temperatures are required to break those bonds. In order for a reaction to occur, molecular bonds must first be broken, and the nitrogen-nitrogen bond in N2 gas simply is too strong for that to happen at a realizable rate at easily achieved temperatures. This is why nitrogen is sometimes mistakenly thought of as a noble gas, and is why electric arcs are required (create points of incredible heat) to initiate reaction between N2 and O2 to yield NO (which typically is then further oxidized to NO2, then bubbled through water to yield HNO3

forundretfrede - 4-3-2003 at 04:05

You should check out the Haber-Bosch synthesis to get an idea of what you are up against:
http://www.seilnacht.tuttlingen.com/Lexikon/HaberBo.htm
The plants for producing ammonia are normally the size of a small town!
Fritz Haber earned a Nobel-prize, and the British wanted to hang him as a war-criminal (he was involved in the German chemical warfare)
(ok, you can have it in English too: http://www.chemheritage.org/EducationalServices/chemach/tpg/...)
:-)

Blind Angel - 4-3-2003 at 10:50

The Electric arc is not infesable.
<url>www.powerlabs.org<url> (currently down for no reason) has good way of makin electric arc, if you don't mind paying for electricity you ould try it....

[Edited on 4-3-2003 by Blind Angel]

[Edited on 4-3-2003 by Blind Angel]

plante1999 - 23-11-2013 at 12:55

Would you mind posting pictures of each reactor?

Galinstan - 23-11-2013 at 14:25

One of the main problems with using electric arc for chemical synthesis is the fact that you are dealing with radicals at high temperatures so you will get a whole soup of different chemicals.
Also i to would be incredibly interested to see how you have dealt with the high pressure required to get a good yield out of the harber process in your home lab

chornedsnorkack - 25-11-2013 at 14:40

Cavendish used 18th century laboratory tools not just to fix nitrogen but to do so quantitatively, discovering argon and measuring its amount. If a 18th century amateur could do that, why not a 21st century one?

watson.fawkes - 25-11-2013 at 16:58

Quote: Originally posted by chornedsnorkack

Cavendish used 18th century laboratory tools not just to fix nitrogen but to do so quantitatively, discovering argon and measuring its amount.

It's too much to say that he discovered argon, but he did catch a sighting of it. The residuum isn't pure argon, even if mostly so.

I looked up the apparatus that Cavendish used for this experiment. I found an account of it in a book from 1851 titled The life of the Hon. Henry Cavendish: including abstracts of his more important scientific papers, and a critical inquiry into the claims of all the alleged discoverers of the composition of water (yes, all that is in the title, in grand 19th century fashion). Google has a PDF available for download on its Google Books page. The work was published as "Experiments on Air" in Philosophical Transactions, 1785. It turns out that Royal Society Publishing has indexed all these and make them freely available. The table of contents of Phil. Trans. 1785 is fascinating all by itself: Erasmus Darwin, Joseph Priestley, William Herschel. The full paper has his original drawings at the end. The paper starts off with how he used the apparatus.

The short version is that he trapped gases in the end of a tube inverted in a bath of mercury. He combusted the nitrogen and oxygen together with a spark from a static electricity generator. While tubs of mercury are available to the amateur, they're not recommend on health and safety grounds. On the other hand, most folks here make sparks with some kind of electrical circuit powered by mains current. A static electricity generator powered by rotational force might be reasonably efficient, perhaps even powered by hamsters.

AJKOER - 25-11-2013 at 17:36

Quote: Originally posted by DDTea

It is a well-known fact that the air we breathe is mostly Nitrogen. However, every time, on various forums, that I've seen someone bring up the idea of using Atmospheric Nitrogen in a synthesis, it is always shot down, and rarely with an explanation (Actually, I've never seen an explanation). What is wrong with using Atmospheric N2?

I'm interested in the idea of an HCN generator (Not MAKING one, but designing one) that passes electricity through a mixture of Acetylene and Nitrogen, and then condenses the resulting HCN. I don't know of a source of OTC Nitrogen, but the most reliable source I can think of is air... Can someone explain to me why this would not work?

Actually, most would think your goals of HCN is a bit far fetched and, in a sense, they are right as it occurs in astrochemistry. See reference "SPECTRA AND PHOTOLYSIS OF PURE NITROGEN AND METHANE DISPERSED IN SOLID NITROGEN WITH VACUUM–ULTRAVIOLET LIGHT" at http://iopscience.iop.org/0004-637X/746/2/175/pdf/0004-637X_... .

Per the abstract:

"Vacuum–ultraviolet light from a synchrotron was applied to record absorption spectra in the region of 105–170 nm
with a resolution of 0.2 nm and for the photolysis of pure solid N2 and CH4 dispersed in solid N2 (CH4/N2 =
1/100 for absorption and 1/500 for photolysis) at 20 K. After photolysis of the icy samples at wavelengths 130 nm
(9.5 eV), 121.6 nm (10.2 eV), and 91.6 nm (13.5 eV), infrared absorption features of products N3, CnN (n = 1–3),
CN2, (CN)2, HCN2, HC2N, C(NH)2, HN3, HNC, HCN, HCCNH+ , and NCCN+ were identiﬁed. We investigated
the dependence on wavelength of the formation of these products and their column densities of formation. We also
studied the ratio of the column densities of HCN and HNC as a function of photolysis wavelength and duration
of irradiation. The mechanisms of formation of the main products are discussed. Our results have implications for
the radiatively assisted syntheses of nitrile molecules in the interstellar medium and on icy surfaces of planets and
satellites in the solar system."

Note, for those in disbelief, the mention of HCN, HNC and other compounds.