five times heavier than air. Apparently it can be sythesized directly from sulfur and flourine which is very inconvienient in the home lab. Any one
have ideas on making it?
ChemkidXenoid - 2-11-2007 at 19:05
I think you mean sulphur hexafluoride and fluorine!
Sulphur hexaflouride and flourine are used for baking...
But, yes, impressive demo, though you wouldn't get me breathing it in!
Regards, XenoidFleaker - 2-11-2007 at 19:20
It's a pretty common demo to swallow some of the gas and let it lower your voice a few octaves, quite the opposite of helium. I don't really think
standing one's head is necessary to remove it from your lungs.
I use SF6 for melting magnesium as a cover gas. Works nicely chemkid - 2-11-2007 at 19:22
good spellers drive me crazy (namely, because i am a terrible one)
@Xenoid: why wouldn't you inhale it? sure impurities in the gas may be a problem, but otherwise it appears to be a simple asphyxiate, just like
helium.
@Fleaker: where did you get the gas?
Chemkid
[Edited on 2-11-2007 by chemkid]Xenoid - 2-11-2007 at 21:10
Quote:
Originally posted by chemkid
@Xenoid: why wouldn't you inhale it? sure impurities in the gas may be a problem, but otherwise it appears to be a simple asphyxiate, just like
helium.
[Edited on 2-11-2007 by chemkid]
Well basically I just think it's a stupid idea! Helium is an inert, natural material so I might just be tempted. Sulphur hexaflUOride on the other
hand is purely synthetic and presumably made from combination of the elements. What's the purity listed on the bottle 99.999%. What's the other .001%.
It was made and measured by people, people make mistakes, all the time. Whose to say that 10 years down the track all the hexafluoride breathers don't
keel over from some sort of fluorine induced lung cancer. It's a bit like the radon breathers and radium drinkers from the 1920's, hmmmm...... that
was considered healthy! It is just unnecessary exposure to chemicals for entertainment purposes as far as I can see!
Sorry to be such a killjoy, .... now, back to my nitric acid making... where was I... Oh yes, breathing in fumes...!
Regards, Xenoid12AX7 - 2-11-2007 at 22:00
Bah, chlorine doesn't even give you cancer. The strong oxidizers fuck you up right away, it's the mild ones like chromate you need to be scared of in
the long term. (Fluorine's bone destroying habit notwithstanding, but if it were 10 ppm of HF in there, a lungful wouldn't be enough to cause that
kind of trouble. After all, if this were the case, you would instead cough it up immediately due to the burning sensation, surviving with perhaps a
burnt mouth and trachea.) If the first 100 ml of gas doesn't choke you, the other 1400 ml won't. (What's lung capacity, 3-4 l or so? Obviously you
don't want to inhale that much SF6 pure, else you'll go unconcious for a spell.)
Speaking of asphyxiation, it's a myth that SF6 "sits in your lungs". The lungs are a very turbulent place and any seperate gasses present are soon
mixed intimately. If you feel yourself going woozy, take a deep breath. If you go unconcious, the brain stem will maintain respiration. It's quite
hard to die of unconfined gas.
Timgarage chemist - 2-11-2007 at 23:48
Industrial SF6 is very pure and completely suitable for the breathing demo- the quality specifications include a test that mice must be alive and show
no ill symptoms after 24 hours in an atmosphere of 80% of the produced SF6 and 20% O2.
There can be a dangerous contaminant in SF6 when not purified properly, namely S2F10, which is very similar to phosgene in its toxicity and ability to
cause pulmonary edema after a few hours delay. The mice test is there specifically to make absolutely sure this impurity is absent, in addition to the
other tests like GC, chemical analysis etc (S2F10 gives fluoride ions upon hydrolysis, while SF6 doesnt hydrolyse at all)...
If prepared at home, it would be very difficult to ensure the complete absence of this impurity.
Besides, I know of no methods other than S and F2 to prepare SF6.kilowatt - 3-11-2007 at 06:07
I have wondered if it would be possible to electrolyze a bath of HF + KHF2, or any other fused fluoride bath, with an anode made of a high sulfur
alloy or composite, or sulfur doped with just enough something to make it conductive, to produce SF6. This would ultimately result in the union of
elemental fluorine and sulfur. The normal scrubbing procedures would be done to remove S2F10 or SF4. The other constituent(s) of the anode would
just dissolve into the electrolyte to be electrolyzed with the rest.Fleaker - 3-11-2007 at 09:25
It's available from a variety of gas suppliers. Mine was from Praxair, but there are various issues to getting it from them without a business
license. It is considered a hazmat item, even thought it is an extremely inert gas. Actually, I think I asked the sales rep that, and she said
something to the effect that it's a greenhouse gas. I certainly see a very heavy gas like that going high high up into the stratosphere...
[Edited on 3-11-2007 by Fleaker]Antwain - 3-11-2007 at 09:30
Well, actually, once it is diluted it will go everywhere. Fractionation of gas in the atmosphere is a non-event except in so fas as light stuff gets
lost. And once up there it would get hit by UV and basically be as good as any CFC ever was. But I agree with you that calling it a 'hazmat' item is
just plain stupid.chemkid - 3-11-2007 at 12:31
How many people are going to buy sulfur hexafluoride to the point where it becomes any significant greenhouse gas. I mean they sell dry ice no hazmat
crap, it turns into a green house gas. Maybe vinegar, baking soda, calcium carbonate, HCl and the hundreds of other ways to make evil greenhouse
gasses should be hazmat items too! I mean, i am environmentally friendly, i recycle compulsively, i print double sided etc etc. But some one is really
worried that the 2000mL of sulfur hexafluoride i release into the atmosphere is going to be the final dose that does earth in?! Anyway rant over.
perhaps the friendly gas supplier will sell me some. Sadly, the one around here is not very friendly and refuses to put liquid nitrogen in a glass
vacuum thermos bottle. However, maybe the ventilation system testers are nicer and
would give me some sulfur hexafluoride. Apparently it is commonly used for ventilation testing which may make things easier.
Chemkid12AX7 - 3-11-2007 at 12:45
Comparing CO2 with SF6 is a stupid point: SF6 is a stronger greenhouse gas than CO2 by many orders of magnitude.
When scientists talk about terraforming Mars, they are referring to mining sulfur and fluoride sources and building SF6 generators.
Timchemkid - 3-11-2007 at 13:32
It is true that SF6 is a stronger greenhouse gas than CO2 however CO2 is produced/released in significantly more abundance and the individual
possession of small quantities of SF2 or CO2 is negligible in comparison to the tremendous amounts of CO2 produced by industry of today.
ChemkidAntwain - 3-11-2007 at 16:04
And at the risk of incurring the mods wrath, we are severly fucking up the Earth.
We should not be producing anywhere as much CO2 as we do.
But you could not carry, even with a ute, hell even with a small truck, enough CO2 to do as much damage as 1kg of SF6. Not that it matters, because we
can and do make this much CO2 over time with our electrical devices and our vehicles.Centimeter - 3-11-2007 at 21:40
Antwain, I feel it is necessary to address your comment on SF6 acting like a CFC in the atmosphere. The CCl2F-Cl bond energy is 73 kcal/mole where as
the S-F bond energy is something like 95 kcal/mole. As you can see, SF6 is unlikely to act as a catalyst in ozone destruction.
On that note, you seem to be confused, referring to CFCs as greenhouse gases. CFCs act as a chlorine radical donor which catalytically converts ozone
to oxygen, subsequently depleting the ozone layer that protects us from harmful radiation. As you can see from the above bond energy, fluorine
radicals are unlikely to be produced in any large quantities.
As far as making SF6, I think it would be quite respectable of a mad scientist to make fluorine gas and react it with sulfur. It sounds like the
electrolysis method of F2 generation wouldn’t be too difficult to pull off. As a plus, when you breath the SF6 in front of your friends, you can
tell them in a demonic voice that you made it with a gas that’s so reactive it burns water.not_important - 4-11-2007 at 03:12
It is true that SF6 is not a threat to the ozone layer. However while SF6 is the strongest known greenhouse gas, something like 22 to 24 thousand
times greaer than CO2 weight for weight, the CFCs are also GHGs although less so because of both the absorption characteristics and their shorter
lifetimes in the atmosphere. CFCs and perfluorocarbons are rated at a thousand to 10 thousand times great greenhouse effect than CO2, depending on the
exact compound.Antwain - 4-11-2007 at 04:14
I find it extremely unlikely that fluorine radicals would NOT be produced. The stuff the comes in at the top of the atmosphere includes X-rays. But
lets say I am wrong about that, and that it doesn't react at all, even up there. That leads to the second part of the catch 22.
There is another factor, in the greenhouse issue.... I can't remember the exact figures, so this may be off by several magnitudes, but methane is
comparable to CFCs as a greenhouse gas. The difference is its half-life in the stratosphere. methane is oxidised very quickly, while CFCs persist. If
SF6 does not attack the ozone layer by being split by hv then presumably it persists too, since it will not react from a strictly chemico-kinetic
point of view due to that wonderful coordinative saturation.12AX7 - 4-11-2007 at 08:46
The ionizing radiation preferentially reacts with oxygen, nitrogen, etc. With SF6 in the ppt range, the amount of fluorine radicals produced is
vanishingly small. The lifetime of SF6 in the atmosphere has been studied and is partly why its greenhouse factor is so large.
I would suppose, when an SF6 does decompose, it soon shatters into smaller bits, the sulfur center reacting with more common hydroxyl radicals,
forming sulfate, which contributes to everyday aerosol. The fluorine, on the other hand, could form, say, oxygen fluoride species first, soon
followed by HF, which is removed from the system in rainwater.
TimMagicJigPipe - 28-11-2007 at 18:47
Why do environmental issues always incite intense argument? I think SF6 should be regulated to a certain extent but not so much as to call it a
"hazmat item" or to prevent individuals from purchasing it. Labeling it as such leads the ignorant masses to believe that it poses a direct and
imminent threat when, in reality, it's barely more "toxic" than the elemental noble gases.
That Al foil boat thing was the shit. I would love to have a cylinder of that stuff to play with.
However, maybe the ventilation system testers are nicer and
would give me some sulfur hexafluoride. Apparently it is commonly used for ventilation testing which may make things easier.