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Author: Subject: Fluorine in quartz?
sbreheny
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Fluorine in quartz?

Hi all,

There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F:

http://www.ebay.com/itm/141404701586

Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this will not attack quartz?

My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains such a mixture inside an excimer laser and whether it is quartz.

Sean
Amos
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As far as I've been told, fluorine attacks and combusts SiO2...

UnintentionalChaos
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Low pressure F2 mixed with He in what is probably annealed quartz has a reasonable lifetime as an element sample. How long exactly, I don't know, but it's prevalent enough that I've heard of it before.

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'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
elementcollector1
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There are ways to even further extend the lifespan of the ampoule, but yes, this person is most likely legitimate.

Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
sbreheny
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 Quote: Originally posted by No Tears Only Dreams Now As far as I've been told, fluorine attacks and combusts SiO2...

Thanks for your reply. I don't think it combusts (maybe finely divided SiO2 would) but rather I think it etches it, until the F2 has all reacted or the SiO2 is etched all the way through and the remaining F2 leaks out.

However, that's what happens with full-strength F2. Maybe if diluted sufficiently with an inert gas, the rate of reaction with the SiO2 is drastically reduced?

I am in the process of making two full (as full as possible) periodic table element sets and I purchased two of these ampoules. I am looking for information about whether this is plausible or likely a scam. I have not received the ampoules yet. Anyone think of any way to test whether there is F2 inside?

The only way I can think to do it would be to put the ampoule inside a larger vessel, along with something that F2 reacts very vigorously with (but other gasses do not so violently react with - like maybe lithium metal or even iron filings), and break the ampoule inside the larger vessel and watch for the reaction. Of course, this would have to be done in a good hood for safety in case the outer vessel broke or leaked. There should be enough metal inside to completely react with the F2 and sequester it. This is, unfortunately, an expensive and destructive test, though.

Sean
Dan Vizine
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If the F2 is free of trace HF, then quartz can have a lifetime of years before becoming cloudy, especially if the F2 is diluted. Over time, the F2 will abstract hydrogen from the inevitable residual Si-OH species and make the HF. The best samples have ampoules that have had the Si-OHs end-capped.

Absorption spectroscopy could confirm it non-destructively. It simply shines light through the sample and looks for what's missing when it comes out.
Pok
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@sbreheny: if you only have amateur equipment your idea of destroying the ampoule is probably the only way to check for fluorine. I bet that you will not detect any fluorine. I don't believe in these "fluorine helium ampoules". If you want to detect it, it is not very logical to take something which will produce a "violent" reaction. You have to find something that will only produce a positive reaction with fluorine, somethin specific. Lithium is the exact opposite of that.

Quartz is not a suitable container for elemental fluorine. A tiny amount (some molecules) of water will act as a catalyst an destroy your fluorine after a while. The only transparent material to store fluorine for centuries are fluorides, e.g. CaF2.
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Theo Gray has a good description of what you need to do to get a long lasting F2 sample in quartz. It's an easy search. Nothing on He dilution and I am dubious.

I am surprised that no one seems to be attempting displays of F2 in PTFE. It seems an obvious choice.
MrHomeScientist
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I feel obliged to link to Theodore Grey's periodic table webpage entry on fluorine, where he describes actual pure fluorine in quartz and the difficulty in preparing such a container:
http://theodoregray.com/periodictable/Elements/009/index.s7....

Scroll down to "Real visible fluorine." I'll also quote it here for posterity.
Dan Vizine
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Fluorine eats PTFE, it's only happy when all the carbon is CF4.

The ampoules that I last saw that were prepared in the Ted Grey way were $600 each. [Edited on 23-10-2014 by Dan Vizine] DrMario National Hazard Posts: 332 Registered: 22-9-2014 Member Is Offline Mood: Underpaid. This is how you can store fluorine gas in a container, and still look at it: put it in a nickel tube which is capped by a CaF2 window (like these) on each side. Of course, the gas is introduced through the nickel tube wall, which is then sealed shut. By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for? [Edited on 23-10-2014 by DrMario] blogfast25 Thought-provoking Teacher Posts: 10334 Registered: 3-2-2008 Location: Old Blighty Member Is Offline Mood: No Mood  Quote: Originally posted by Dan Vizine The ampoules that I last saw that were prepared in the Ted Grey way were$600 each.

He's a great guy but not much of an authority on anything.

HgDinis25
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 Quote: Originally posted by DrMario This is how you can store fluorine gas in a container, and still look at it: put it in a nickel tube which is capped by a CaF2 window (like these) on each side. Of course, the gas is introduced through the nickel tube wall, which is then sealed shut. By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for? [Edited on 23-10-2014 by DrMario]

Having an ampoule of 30% Fluorine is a mean in itself. It's for the element collector as a Kilo of cocaine is for the drug addict
Dan Vizine
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 Quote: Originally posted by DrMario By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for? [Edited on 23-10-2014 by DrMario]

Really? You've never run across an element collector?

I've got one. Makes me feel complete....
DrMario
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I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed.

Fluorine, on the other hand, is probably not much fun when consumed

No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of happiness anywhere.
HgDinis25
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 Quote: Originally posted by DrMario I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed. Fluorine, on the other hand, is probably not much fun when consumed No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of happiness anywhere.

hahahaha
Usually the biggest problem is actualy getting the Fluorine...
DrMario
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 Quote: Originally posted by sbreheny Hi all, There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F: http://www.ebay.com/itm/141404701586 Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this will not attack quartz? My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains such a mixture inside an excimer laser and whether it is quartz. Sean

Here are a few random comments: the seller doesn't even mention the amount of fluorine/the volume of the ampoule/the partial pressures of the gases. You would think he/she could be arsed to put that in the eBay description, for a whopping $90! How 'bout this: I'll seal an ampoule and tell you it contains 33% fluorine, for the low price of$40.
HgDinis25
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Quote: Originally posted by DrMario
 Quote: Originally posted by sbreheny Hi all, There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F: http://www.ebay.com/itm/141404701586 Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this will not attack quartz? My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains such a mixture inside an excimer laser and whether it is quartz. Sean

Here are a few random comments: the seller doesn't even mention the amount of fluorine/the volume of the ampoule/the partial pressures of the gases. You would think he/she could be arsed to put that in the eBay description, for a whopping $90! How 'bout this: I'll seal an ampoule and tell you it contains 33% fluorine, for the low price of$40.

Then some mad chemist is going to take some refraction index measurments using top of the line, 10 digits past the coma, equipment. All to confirm some air is present. At least the quartz ampoule is usefull...
Dan Vizine
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Actually, I've talked with the sellers, Stefan and Chantal ( I think), anyway they were interested in buying F2 from me when I was entertaining the thought of building a F2 generator. So, for what it's worth, I believe that they are probably legit.
DrMario
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 Quote: Originally posted by HgDinis25 At least the quartz ampoule is usefull...

Not for long, if it's filled with fluorine gas

BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element collection. And we all know how bitchin' expensive that astatine is...
HgDinis25
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Quote: Originally posted by DrMario
 Quote: Originally posted by HgDinis25 At least the quartz ampoule is usefull...

Not for long, if it's filled with fluorine gas

BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element collection. And we all know how bitchin' expensive that astatine is...

Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a pice of the mineral.
DrMario
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 Quote: Originally posted by HgDinis25 Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a pice of the mineral.

That would be fluorite, CaF2 (which, BTW, I mentioned earlier).
UnintentionalChaos
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Quote: Originally posted by HgDinis25
Quote: Originally posted by DrMario
 Quote: Originally posted by HgDinis25 At least the quartz ampoule is usefull...

Not for long, if it's filled with fluorine gas

BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element collection. And we all know how bitchin' expensive that astatine is...

Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a pice of the mineral.

It's called fetid fluorite or Antozonite. Irradiation of the calcium fluoride by decaying uranium causes small inclusions of fluorine gas to form.

Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
Dan Vizine
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 Quote: Originally posted by DrMario I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed. Fluorine, on the other hand, is probably not much fun when consumed No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of happiness anywhere.

I do have a comment. It won't work because you have no way to make gas tight seals between the salt and the metal tube that won't be attacked by the halogen.
Arcuritech
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 Quote: Originally posted by Dan Vizine ...It won't work because you have no way to make gas tight seals between the salt and the metal tube that won't be attacked by the halogen.

Even the idea of creating a direct bond between the Ni and the CaF2 isn't so inconceivable because the nickel withstands attack by F2 by the formation of a NiF2 passivation coating on contact. That layer could be affixed to the the CaF2 using a lower melting fluoride salt as a "solder".

*edited to remove typo*

[Edited on 2014-10-24 by Arcuritech]

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 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Fluorine in quartz? Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues