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panzerkampfwagen
October 23rd, 2007, 12:22 AM
I have recently come across some info about an abandoned NASA project using Li, H, F as a rocket propellant. It turns out that it was abandoned because it was far too volatile and ended up destroying the rocket (after displaying a specific impulse of about 14000Ns/Kg) in a small-scale experiment. I was thinking that if such a combination could be detonated fast enough (high heat, high velocity primary), it could be used as a form of thermobaric explosive, along the lines of blowing up an acetylene tank.

I was also trying to find a reasonable method of containing/pressurizing (or producing as part of the explosive?) fluorine gas. It might be a little difficult to procure enough fluorine, but I think that it would be worth it. CaF2 is not very expensive and fluorine can be prepared by electrolysis of CaF2. Or, for some more fun, if I am not mistaken, some lithium ion batteries are lithium fluoride, so if you could produce an incredibly high current, it may be possible to do an ultra fast electrolysis and produce all of the compounds at the same time.

I think that substituting sodium for the lithium would make it significantly more feasible with a minimal loss of power. Lithium can be rather hard to produce, and all reactive metals are expensive to buy.

nbk2000
October 23rd, 2007, 01:21 AM
A Mr. Wizard, huh? :rolleyes:

High-pressure fluorine would, if it didn't kill you, be sufficent in itself to destroy anything that came in contact with it, making an explosion pretty much frosting on the fluorine cake.

Cost? Astronomical.

Effectiveness? Nothing that an equally expensive amount of explosives wouldn't achieve 10x better.

If you want to bother with elemental fluorine, why not make Chlorine Trifluoride? A gas that sets fire to nearly anything it touches...hair, skin, asphalt. :)


N-stoff ("substance N"), chlorine trifluoride was investigated for military applications by the Kaiser Wilhelm Institute in Nazi Germany from slightly before the start of World War II. Tests were made against mock-ups of the Maginot Line fortifications, and it was found to be an effective combined incendiary weapon and poison gas.
...
Handling concerns, however, prevented its use. Clark summarized the difficulties, "It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively."[8][9]

Source: http://en.wikipedia.org/wiki/Chlorine_trifluoride

panzerkampfwagen
October 23rd, 2007, 07:30 PM
How about HSbF5? It has a pKa of somewhere around -25 and will explode or otherwise annihilate anything except for Teflon, probably because of its high fluorine content. I believe that it is the most powerful Bronsted-Lowry acid. Electronics duster is C2F5, so I would think that you could use an antimony electrode and some source of hydrogen (though I would not suggest water) and produce it via electrolysis. Or maybe it would be possible to use some antimonic acid (if it exists) and C2F5 as the fluorine donor to produce HSbF5 through what could be a fairly simple reaction, sans the elemental fluorine.

nbk2000
October 23rd, 2007, 10:15 PM
Please don't start with 1+1 chemistry. It's nowhere near that simple and will get you banned.

Bert
October 23rd, 2007, 10:17 PM
Conjecture has it's place. Immediately before experimental attempts to prove or disprove the theory, ideally. Are you going to try any of this? Can you please have someone video it from a goodly distance up wind if you do? I'd kind of like to watch, and I suspect you won't be posting your lab notes if you succeed with the proposed substances.

panzerkampfwagen
October 24th, 2007, 06:59 PM
Sorry, I did not mean to imply that I though that it would turn out to be "1+1 chemistry." I was just throwing out a basic template and wondering if anyone has ever heard of a synthesis method similar to that.

In any case, it turns out that HSbF5 is the prodct of HF and SbF5. For some reason, SbF5 is not the easiest chemical to find info about. Sb is frequently used in low-temp casting alloys for fishing weights, solder, and musket loaders (though rarely used for the last purpose). Antimony first forms SbF3 and must then be converted to SbF5. I would think that the other fluorides could be added by HF, but it would not be very efficient, since I could not see it being easy to push more fluorines onto a compound that has already reached its most stable form. Plus, I would not appreciate unnecessary exposure to HF. I have no idea what kind of catalyst could survive such a reaction. Iridium may be able to, but it is also not exactly the cheapest metal.

If I could find a substance that is denser than SbF5 and will not react with it (SbF3) or dissolve it, it may be possible to release elemental fluorine from below it through electrolysis of HF (dissolved in aforementioned solvent that will not react with the reactants or the products, but will dissolve the HF) and hope that the SbF3 would "soak up" all of the fluorine being produced. It's a long shot, but it might just work, and it might not be absurdly dangerous. The only question is where I can find HF and equipment that it would not destroy (teflon?).
It seems rather dangerous, but from what I have read, it would be worth it. And anways, I am not exactly intending on handling anything myself and F2 gas can't exactly sneak up on you. If I am not mistaken, it looks alot like Cl2 and forms clouds that should be rather easy to see. I am not intending on jumping right into this, so I would like to some small-scale test runs right after I get the right equipment and materials.

nbk2000
October 25th, 2007, 10:27 AM
Fluorine doesn't have to 'sneak up' on you, in much the same way a Great White shark doesn't have to sneak up on you...it just tears your apart before you know what has happened to you or have any chance to protect yourself.

You may wish to read up on the history of fluorine and see what happened to a lot of professional chemists who worked with it...blindness, debilitating lung injury, and death.

These guys had state-of-art labs (for the times) and where professionally trained chemists, and they STILL got maimed and killed by fluorine.

Not to dissuade you from trying, but don't be naive about the danger (or cost) of handling such an element.

Charles Owlen Picket
October 25th, 2007, 11:36 AM
Fluorine is a motherfucker. I knew a guy who sold chemicals for a living and was not a chemist; he also grew quite complacent. He knew Fluorine was vicious but had some in a plastic bag on a counter in the back of his place.

He was a nice guy. But what he did was a really stupid move. He originally thought he had gotten sick. Then he thought he had cancer. Then I stopped hearing from him. Don't fuck with Fluorine.

panzerkampfwagen
October 25th, 2007, 08:22 PM
First of all, I was not intending on putting the only chemical to ever react with all but two of the noble gasses in a plastic bag. I was also not exactly intending on dealing directly with elemental fluorine. I was referring to something related to the gas collection process via bubbling through water, just replacing the water with SbF3 and an appropriate solvent.

To make my idea more clear, I am talking about electrolysis of HF or some other convenient fluorine compound that does not take substantial work to melt, then transporting it via tubing that will not be annihilated by the F2 and allowing it to contact antimony sheets/rods/whatever immersed in something that SbF3 and SbF5 will dissolve in. As the Sb undergoes reaction, it will go into solution and when all of the antimony has reacted, the fluorine should turn to the dissolbed SbF3. Otherwise, direct addition of HF may be required.

What I had not noticed before is that Sb is one of those annoying elements that has a +6 charge, so it should not be too difficult to add the extra fluorines. With any luck, it might skip the intermediary SbF3. SbF5 is a strong Lewis acid, while SbF3 is not, so I think that I should be able to test it directly and determine what it actually is. In any event, once the SbF5 is created, the hard part is over, since I know for a fact that SbF5+HF=HSbF5.

I just have not idea where to start looking for HF, or if there is a better source of fluorine for the initial Sb+F2 reaction, but I should be able to find one if there is (I'm sure Wikipedia knows). I just hope that the Fluorine will make it through the solvent. If it can't, I will have to leave it out, and since it is the only thing that will definitely contain the Fluorine (aside from Teflon or plasma or some other highly infeasible thing), I will have to find some way to make it safer. By the way, can borosilicate glass survive fluorine? I know that it eats other kinds of glass, but I would hope that Pyrex would be strong enough to at least dramatically slow the reaction.

Bert
October 25th, 2007, 10:50 PM
Go to a rock shop/lapidary store. Pretty crystals of Calcium Fluoride are usually available. Used to cost a couple of dollars an ounce when I last bought some. Cheaper than reagent grade-

Don't work where no one will find your body, and leave a note regarding what you were working with in case you can't talk.

Chemdabbler
October 26th, 2007, 03:04 AM
We use HF to clean scratched or scored borosilicate glassware before fire polishing the damage out, it works by dissolving the fine high-surface area glass dust out of the crack, you then wash it out before it frosts the rest of the piece. So in a word - no. - borosilicate will not contain HF or even F2 gas safely or for long. We have containers made of polyethylene and containers made of PTFE, and even double-gloved and covered with barrier cream, i HATE to work with the stuff.

As far as where you can get it, should you be foolish/invincible enough to wan t it, you might look for a friendly scientific glassblower, or try to convince a chemical supplier that you are a glassblower working with boro, claiming to be a bongmaker might work. Wikipedia also claims that some car wheel cleaning sprays contain HF, but at what concentration and with what other chemicals it doesn't mention.

There's an interesting (to me) article on Theodore Grey's Periodic Table Table Flourine Page (http://theodoregray.com/PeriodicTable/Elements/009/index.s7.html) about the sheer difficulty involved in storing F2 in any kind of silicon glass, it can be done, but really, don't bother.

*laughs* Wikipedia's HF page (http://en.wikipedia.org/wiki/Hydrofluoric_acid) has this gem:
"A concern for emergency services is the theft of drums of hydrofluoric acid, possibly after being mistaken for hydrochloric acid which has uses in the preparation of all kinds of substances, including in the clandestine production of drugs such as methamphetamines."
Good god, that'd be a lab accident I'd pay handsomely to see (on tape...)



Flourine is fascinating stuff, but not anything i'd voluntarily work with/expose myself to.

panzerkampfwagen
October 26th, 2007, 08:50 PM
Is there any chance that I could find some place to buy SbF5? Seems like a stretch, but stranger things have happened, and you could probably buy just about anything online. If not, I am thinking about just containing all of the reactions in the container that the HF comes in. It can obviously resist HF, so it seems like it would work. Is there any fluorine compound that is reactive enough to use for any synthesis but will not kill you if you look at it funny?

Chemdabbler
October 26th, 2007, 09:12 PM
"If not, I am thinking about just containing all of the reactions in the container that the HF comes in. It can obviously resist HF, so it seems like it would work."

This logic strikes me as dangerously faulty... i mean, what if the reaction produces gas or heat beyond the ability of the container to contain, or produces something that can degrade, dissolve or penetrate it? It's your life, but before you start mixing, i'd suggest looking long and hard at the various and nasty possible consequences of contaminating yourself with any reactive flourine compound.

AcMav
October 27th, 2007, 07:16 PM
So on your behalf Panzer I decided to do a search and see if I could perhaps find a dealer of Antimony Pentaflouride in the world, And low and behold there are 5, 2 of which are in Germany, 1 in China, 1 in Belgium and 1 in the United States. Unless you happen to be a multimillionaire I doubt you're going to be able to afford the stuff because the United States supplier is only willing to contact a legitimate company and deal with amounts in units of Kilograms or Tons.
I'd say this is a lost cause and just give it up.
Incase you want to do some more searching of your own, the CAS number for Antimony Pentaflouride is 7783-70-2.

panzerkampfwagen
October 28th, 2007, 12:23 AM
Thanks, AcMav. Unfortunately, I regret to inform you that I am not a millionaire or a company (though if I could find someone to sell HSbF5 to...). I am not surprised that half of them (fine, 2/5) are in Germany. They seem to make everything of quality now.

I had not thought of the heat of the reaction exceeding the max temp of the origional container, but then again, that's why I posted here before running off and doing something stupid (potentially, but why take the risk?). Platinum is a little too expensive, but it would work. Then again, so would solid helium, but that's not even remotely feasible. I still think that Teflon would probably be the best bet, though its heat resistance isn't particularly good. Does anyone happen to know whether Sb has any chance of replacing Ca in a single replacement? I would not expect that it would, but it would make for an incredibly convenient reaction, completely skipping over the undesirable gaseous fluorine.

Maybe if I put the Sb in a gigantic tub of toothpaste and left it in an iron furnace and cryo froze myself for a few centuries, it may make SbF5, though I doubt it (particularly the cryo part).

Are there any other convenient (common, cheap, and not "one strike, you're out") fluorine compounds? I've been searching through my secret database (Wikipedia), but none of them seem particularly "user-friendly." With any luck, I may be able to use some of the electronic spray duster that I have piling up. It is, after all, pentafluoride and not particularly dangerous (for fluorine). C-F bonds should not be too hard to break, but then we go again with the fluorine gas. I'll try to find a solvent that it will dissolve in so that maybe the duster can be reacted directly.

Also, does anyone know anything about AlF3? I can't find much, but since
Al2O3 forms a passivation layer, I would hope that AlF3 would too. That would be the ideal, since aluminum conducts heat rather well, so I could dissipate the heat into something else (sand?), and if my theory holds true, it should form a solid, nonporous, and inert passivation layer that will contain the fluorine. Give it a Teflon bottom and skirt (on the inside, of course) and it will be able to withstand the HSbF5. It should also be easy to rig up an HF drip that could add the HF to the SbF5 without my opening the container (big plus), and it should control the reaction rate. Actually, an aluminum-coated (is this possible?) Buchner flask would be ideal, since I could pump out any residual fluorine gas that would make the opening of the container "eventfull." I could add a one-way valve on the top to let air in so I don't accidentially vaporize the product(s?).

Bert
October 28th, 2007, 12:25 PM
Are there any other convenient (common, cheap, and not "one strike, you're out") fluorine compounds? I've been searching through my secret database (Wikipedia), but none of them seem particularly "user-friendly." ?).
Sigh. Calcium fluoride (fluorite, fluorospar) is easily available. There are hundreds of listing on eBay for it, plus every rock shop I've ever been in has it. If 17th century man could use it to make hydrofluoric acid with sulfuric acid, even a kid relying on Wikipedia as his primary source could figure it out. With a little more gumption, he could also figure out electrolytic production of Fluorine gas and kill himself. Of course, the equipment and materials would likely cost more than his allowance...
With any luck, I may be able to use some of the electronic spray duster that I have piling up...... C-F bonds should not be too hard to break
You don't have any idea why that bit is funny, do you?

Learn to walk (or even crawl) before trying to run. Go get a HANDS ON grounding in basic chemical knowledge, lab equipment and techniques, rather than sitting at your computer speculating without sufficient background or any attempt at an experiment.

Or go to TOTSE where it's the style.

In the meantime, I suggest this thread be locked.

nbk2000
October 28th, 2007, 03:29 PM
It'll stay open, but the OP is no more.

rightway
October 31st, 2007, 11:01 PM
Interestingly, electronic spray duster could be used to produce HF (though not in a direct reaction to form SbF5).

C2H4F4+O2+heat (relatively little) --> 2HF+2HFC=O(carbon oxyfluoride)

Carbon oxyfluoride is very, very toxic (2-5ppm (OSHEA reg.)). Fortunately, it decomposes under water or when exposed to a hot surface. The MSDS I was reading said that a hot surface may cause too fast of a decomposition and cause a small, but rather toxic explosion. I would think that collecting it over (really in) water would be effective.

Carbon oxyfluoride does not have defined products of decomposition; every time is like a mystery box, you never know what you might get. More HF may be produced, but there is no way to tell until someone tries it. Carbon oxyfluoride is rather corrosive, though (dangerous in every way but flammability). Therefore, for the sake of safety, I would definitely not use glass or steel containers at any point when dealing with Carbon oxyfluoride (not to mention the HF). If it is collected over water, whatever gaseous products are produced should probably be vented as quickly as possible.

Since the decomposition is not exact, I could not guarantee the purity of the HF, but if purity is essential, I am sure that there is a way to remove whatever impurities there are. Otherwise, it should not matter too much. If you are trying the synth. for HSbF5 (just the SbF5 to HSbF5 part) that panzer proposed, the water must be removed from the equation, which would unfortunately make the collection of the products much more complicated and dangerous.