I've had some very nice experiences with that molecule. I've also scared my
self to death with it. One experiment that comes to mind resulted in no damage,
injury or harm whatsoever. I mixed a small amount in a controlled manner in a
lab pressure vessel with nitromethane to determine miscibility as a possible
monopropellant. Someone suggested this might be a good idea and I very
excitedly decided to try it without giving it sufficient consideration. As I
looked through the small viewing window, most of the blood rushed from my face
according to someone in the room at the time. I opened a needle valve to let
the mixture quietly vent and walked away. That was a long time ago and I
promised never to do it again in such a casual manner.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
In a way I am not too surprised. Nitrous is unusual stuff.
The molecule is linear N=N=O but with a positive charge on the middle nitrogen
and the negative charge spread out between the nitrogen and the oxygen on the
ends.
The decomposition of nitrous gives N2 and O2 and a heck of a lot of energy,
about 85 kJ/mol when in gaseous form - the nitrogen triple bond is one of the
strongest known. At compressed liquid nitrous densities the equivalent energy
released is much higher, about 180 kJ/mol from a quick BOTE.
The precise mechanisms of the reaction are not known, but they are known to be
complex (to put it mildly!). There are potentially at least one first order and
three second order rate-determining mechanisms - the dominant one changes with
density and temperature. It is however generally thought that the most
important one is N2O -> N2 + O* where O* is a lone oxygen atom.
However we do know that the activation energy is very high, above 250 kJ/mol.
The bonds in the molecule are strong, and the ends of the molecules, being
partly negatively charged, repel each other and prevent close contact.
This means that in order to get nitrous to decompose you need a high
concentration of energy in one spot.
However, because the amount of energy given off is so high, and much higher in
mixtures with organic compounds (the C-O bond in carbon monoxide is the only
bond between two atoms which is stronger than the nitrogen triple bond), the
total amount of energy needed to start a self-sustaining reaction is not large.
The requirement for a high concentration but low total quantity of required
energy to initiate a self-sustaining reaction means that a nitrous/organic
mixture can appear benign in tests where the amount of energy used is
substantial but the concentration of energy is limited; but not be benign in
use.
This is especially true when highly energetic organics like acetylene are used,
and the minimum deflagration radius (and detonation radius, and DDT length) is
tiny.
Nitrous is also a horrible long-lasting ozone-depleting and greenhouse gas.
Frankly, about the only justifiable use for nitrous is in childbirth and
colonoscopies. And dentistry, maybe.
Peter Fairbrother
(who can be a half-century behind the times when talking chemistry)
