chemoleo - 6-8-2004 at 16:23
Well a friend of mine is researching gasses in volcanic vents. One of them apparently is ozone (albeit at small conc). I am quite curious as to the
chemistry behind it.
At this point, I have no educated guesses, except maybe that it may involve one of the following:
SO2, SO3, NO2, NO, HNO3, H2O, CO2, H2, CO, H2S, extremely small amounts of HF, F2 and Cl2, heat (<1300 deg C), and molten minerals (possibly
catalysis). Of course let's not forget the atmospheric gasses.
All these are present, to a smaller or greater extent, in volcanic vents.
Anyone cares to make a guess as to how the O3 is made?
[Edited on 7-8-2004 by chemoleo]
darkflame89 - 7-8-2004 at 01:04
I have read in a certain book that there is increased lightning discharges around a volcano during a volcanic eruption. If this is true, then the
ozone production together with the production of nitrogen monoxide, is then explanable via the usual atmospheric reactions that occur when lightning
occurs. The sulfur oxides are the product of burning sulphur, as is the same of the hydrogen sulphides. I guess that the fluorine gases and the
chlorine gases come from the molten rocks themselves. The acid present is then the result of all these acidic gases produced dissolved in water vapour
and steam.
froot - 7-8-2004 at 01:10
If I may I can theorise that:
Considering the extreme energy levels and temperatures inside the vent, normal energy potentials governing chemical reactions that we are used to
become considerably less of a determining factor as to what molecules are formed. A constant swapping of elements and radicals between molecules may
be happening which is arrested as soon as the hot vent gasses exit the vent and cooled ending up with some random unexpected molecules. I suppose that
the vent composition may vary from volcano to volcano depending on the chemical composition of of the magma which should be the source of the vent
gasses in the first place.
Just a brain fart. 
chemoleo - 7-8-2004 at 01:47
Darkflame, you are indeed correct about the lightening. However, I am talking about volcanic gasses coming out of vents, not eruption sites. These
vents pretty much smoke all the time, but often never erupt.
Froot I totally agree that any nascent high temp reactions are rapidly stopped as soon as the gasses exit the vent. This may explain why the ozone
isnt destroyed (i.e. oxidises something) as soon as it is formed. Also, pressure conditions inside and outside the vent are totally different.
Also, the gasses do indeed vary, but more in terms of proportions, than compositions. The gasses I mentioned are produced in most vents, with
exception of maybe chlorine and fluorine.
Well the only reason why I listed these gasses in the first post was to get us to see what is available for reaction.
Somehow, knowing the surprises chlorine often has in stock, I'd guess that it is involved in the formation of ozone.
[Edited on 7-8-2004 by chemoleo]
vulture - 7-8-2004 at 06:29
To my knowledge, chlorine radicals will only catalyse the breakdown of ozone. However, nitrogen oxides can both support and suppress the formation of
ozone.
Was the volcano vent site on a high altitude, eg higher than 1500m? The increased UV irradiation in combination with the nitrogen dioxides (think
"ozone alert" during hot summer days) might promote ozone formation.
[Edited on 7-8-2004 by vulture]
[Edited on 7-8-2004 by vulture]
chemoleo - 7-8-2004 at 08:49
Thats a good point. On hot summer days... when the sun is high... UV is strong, and the gases react as soon as they come out of the vent, with NO2 (?)
to form NO and O3???
Hmm... thats too much speculation for my liking though.
Anyway, as to the NOx reacting, is that what u meant?
Yes, chlorine radicals suppress it, hence hte action of chlorinated hydrocarbons on the ozone layer.
guy - 7-8-2004 at 19:58
When fluorine reacts with water it produces HF, O2, and O3.
chemoleo - 7-8-2004 at 21:15
Yes, you are right, it is quoted here:
http://www.webelements.com/webelements/elements/text/F/chem....
Interesting! It looks like both reactions occur at the same time?