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Upsilon
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Apparatus for generating HF
I ordered some CaF2 because it was easily the cheapest fluoride salt I could find. However, it is insoluble in water and I need to find a
way to make other fluoride salts out of it. The only way I can think of is to treat it with sulfuric acid, generating HF gas which I can then bubble
into a solution of a carbonate salt. However I do not want to do this with my glassware, since HF will attack it. I am thinking of using discarded
plastic water bottles and rubber/vinyl hose. Will these be ok for this process? And which is more ideal for the hose - rubber or vinyl?
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crazyboy
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This is a really bad idea, please do not do this. HF is very toxic, this reaction takes place at elevated temperatures that will melt the plastic.
Even professional chemists avoid gaseous HF whenever possible.
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Bert
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I would not do this thing until and unless you research the history of famous 18th-19th century chemists injured and KILLED while attempting to work
with Flourine compounds, working to isolate elemental Flourine.
Google "Flourine martyrs".
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Humphry Davy of England: poisoned, recovered. George and Thomas Knox of Ireland: both poisoned, one bedridden 3 years, recovered. P. Louyet of
Belgium: poisoned, died. Jerome Nickels of Nancy, France: poisoned, died. George Gore of England: fluorine / hydrogen explosion, narrowly escaped
injury. Henri Moissan of France: poisoned several times, success, but shortened life.
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After doing that research, you will find out which common, ductile, easily worked metal may become coated with a layer of fluoride and be useful for
the endeavor.
Please have a friend knowledgable of chemistry advised of your work, asked to check on you occasionally and directed to post your lab notes here in
the case of your untimely death.
Not being facetious, we will want to know. Might save some other amateur's life-
[Edited on 15-9-2015 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Cou
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wtf do not mess with hydrogen fluoride unless you want death
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Hawkguy
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Actually this takes place at like room temperature. You'll need Teflon or PTFE or something, for the apparatus and also for a container. Actually, the
receiving flask has to be Teflon I think.
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Upsilon
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Looks like this isn't going to be an option then. Is there anything else I can do with this calcium fluoride to convert it to other fluoride salts,
like NaF?
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Bert
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Thread Moved
15-9-2015 at 15:40 |
j_sum1
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I have a question and a comment.
What do you actually need the fluoride salt for anyway?
If it was me, I would simply buy what I needed in this case. Everything that I know about HF and fluoride salts in general indicates that it is not
something to be trifled with.
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Upsilon
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Quote: Originally posted by j_sum1  | I have a question and a comment.
What do you actually need the fluoride salt for anyway?
If it was me, I would simply buy what I needed in this case. Everything that I know about HF and fluoride salts in general indicates that it is not
something to be trifled with. |
I don't necessarily have an actual need for them, per se, but it would be cool to have them. Kind of like element collecting. And I could
possibly find a use for a water-soluble fluoride salt in the future.
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Texium
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Sodium fluoride is quite cheap from Seattle Pottery Supply. Much better to buy some from there rather than dealing with hydrofluoric acid, nevermind
gaseous HF. Especially when you are not well equipped or very experienced and only want it because it would be "cool to have."
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violet sin
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that is pretty freaking affordable 
http://www.seattlepotterysupply.com/Merchant2/merchant.mvc?S...
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Upsilon
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Dangit, I really need to start looking closer at these small pottery stores.
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woelen
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If you want soluble fluoride salts, then NaF also is not the best choice. It is soluble in water, but only quite sparingly. A better choice would be
KF, KHF2 or NH4HF2. The latter two are available from eBay for cheap.
But keep in mind, fluoride salts also are quite dangerous and they attack glass as well, albeit less energetically than HF. If you get a solution of
ANY fluoride on your skin, IMMEDIATELY wash it away, even if it is just "plain" sodium fluoride or ammonium bifluoride. Playing with fluorides is not
like playing with the other halides, they are much much more dangerous.
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MrHomeScientist
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I have some ammonium bifluoride (bought from eBay) and I can say that this is by far the most dangerous chemical I own. I used it in my synthesis of
NdF<sub>3</sub>, and the whole time my nerves were on edge. I donned all my safety gear, plus some extra precautions, and moved very
slowly and deliberately. Fluoride is an insidious poison - very small amounts will kill you, and burns may not be painful until a day after a spill
(so you may not realize it until it's too late). I bought calcium gluconate gel (also from eBay) and I keep this nearby to my bifluoride in case of
emergencies. If you buy a soluble fluoride salt, also buy this gel. It's expensive, but your life is worth $50. If a spill occurs, wash it off
immediately, apply the gel generously, and go to the hospital. We can't stress enough the dangers of this chemical.
Taking that into account, I'd avoid working with soluble fluorides until you have a real need for them.
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battoussai114
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Anything that contains fluorine (and isn't teflon) is a big nope for me. Way too dangerous for my home lab and, in fact, even here at the university I
study there aren't many researchers willing to work with HF or Fluorine.
| Quote: Originally posted by MrHomeScientist | I have some ammonium bifluoride (bought from eBay) and I can say that this is by far the most dangerous chemical I own. I used it in my synthesis of
NdF<sub>3</sub>, and the whole time my nerves were on edge. I donned all my safety gear, plus some extra precautions, and moved very
slowly and deliberately. Fluoride is an insidious poison - very small amounts will kill you, and burns may not be painful until a day after a spill
(so you may not realize it until it's too late). I bought calcium gluconate gel (also from eBay) and I keep this nearby to my bifluoride in case of
emergencies. If you buy a soluble fluoride salt, also buy this gel. It's expensive, but your life is worth $50. If a spill occurs, wash it off
immediately, apply the gel generously, and go to the hospital. We can't stress enough the dangers of this chemical.
Taking that into account, I'd avoid working with soluble fluorides until you have a real need for them. |
Isn't it necessary to inject the gluconate bellow the place were the fluoride got you? Or is it HF that require it?
Batoussai.
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MrHomeScientist
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The stuff I have is a tube of gel, applied topically. It's called Calgonate: http://www.calgonate.com/calgonate_gel.php
That page also has handy application instructions.
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ave369
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I have a small jar of sodium fluoride sitting on the shelf in my reagent cabinet. I didn't buy it specifically, I've bought a chemistry set with it
included. It sits there and does nothing, because I stay away from experimenting with this thing unless it's absolutely necessary.
That chemistry set described experiments with fluorides and HF for schoolchildren. One is making a mixture of NaF and oxalic acid and using it to etch
glass. The other is a modified version of the "fake blood" trick: after the "blood" (iron thiocyanate complex) shows up, apply a cotton ball wetted in
a solution of NaF to your arm to make the blood vanish.
Fluoride.
For schoolchildren.
On the skin, Carl!
... on the other hand, maybe we Russians are just hardier and more resistant to all kinds of shit...
[Edited on 16-9-2015 by ave369]
Smells like ammonia....
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Upsilon
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Alright all, you've successfully talked me out of this (for the time being, anyway). I suppose my calcium fluoride is just going to sit around for a
while. No big deal, I bought 2 pounds for a measly $3.
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Little_Ghost_again
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| Quote: Originally posted by Upsilon | | Alright all, you've successfully talked me out of this (for the time being, anyway). I suppose my calcium fluoride is just going to sit around for a
while. No big deal, I bought 2 pounds for a measly $3. |
First the good news, well done for actually listening as many dont but we rarely get any more posts from them.
Now the bad news, because you listened you are unlikely to be winning the Darwin prize this month  .
Playing with that stuff is a bit like trying to find out what 1Kg of Arsenic taste like.
Maybe the Calcium Fluoride is cool enough for now 
Dont ask me, I only know enough to be dangerous
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careysub
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This reminds me of the "sand gas" (silicon tetrafluoride) thread(s):
http://www.sciencemadness.org/talk/viewthread.php?tid=8
http://www.sciencemadness.org/talk/viewthread.php?tid=22494
"Thrilling Stunts with a Glass Eating Chemical!" Popular Science proclaimed in January 1938.
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mayko
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This account of an HF burn helped spark my morbid fascination with fluorine (the chlorine trifluoride entry in Merck also contributed)
| Quote: |
The side of the bottle carried the warning CAUTION: DO NOT USE WITHOUT GLOVES. William didn’t read that bit, however, and he removed the cap from
the bottle, spilled some liquid onto a rag, and began rubbing it into his stained coat. But as the stain began to fade, his right hand, the hand he
was using to apply the liquid, began to hurt. After 20 minutes the pain was so intense that he had to stop. Within 40 minutes he could no longer move
his fingers. Frightened and in terrible pain, he managed to drive himself to our emergency room. Fortunately, he brought the rust remover with him.
While William writhed in agony, I took a close look at his right hand. Except for some mild swelling of the fingertips, it looked just like his left
hand. But if I even gently pressed on his fingernails, he grimaced and begged for a painkiller. |
al-khemie is not a terrorist organization
"Chemicals, chemicals... I need chemicals!" - George Hayduke
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MrHomeScientist
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Something you can do with calcium fluoride is use it as a flux in thermite reactions, to promote metal/slag separation and increase your
yield! Here's my page on various titanium thermites I tried using CaF<sub>2</sub>: http://thehomescientist.blogspot.com/2012/09/titanium-thermi...
My procedure was from blogfast's experiments (I think he actually invented this process), which I link to at the top of my page.
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Upsilon
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So I have another dilemma that may involve HF - trying to make titanium dioxide useful (basically I need to dissolve it). I've been doing some
research and it's apparently extremely difficult to do. So far I have found several possibilities, but I need help choosing the most effective method:
1) Concentrated hydrofluoric acid. This one is pretty much a "no"
2) Concentrated nitric acid with a small amount of HF. This one is a possibility; I could have everything I need in a single vessel that I can just
leave by itself and have the reaction go. By that I mean putting the titanium dioxide, nitric acid, calcium fluoride, and sulfuric acid all together
with a heat source. The HF will be generated and immediately reacted with no dangerous intermediate steps. Of course I would stay back from the
vessel.
3) Hot concentrated sulfuric acid. I read that this reaction occurs very slowly but it does occur. Not completely sure if it is valid or not.
4) Dissolving in molten sodium bisulfate. This looks like the most appealing to me, since sodium bisulfate melts at quite a low temperature, but I'm
not sure of the extent to which it will actually dissolve.
I am also open to any ideas others may have.
[Edited on 18-9-2015 by Upsilon]
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battoussai114
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Oxalic Acid under UV should dissolve it. Worth noting that I only read the abstract.
Attachment: phptG99eA (146kB)
This file has been downloaded 423 times
Batoussai.
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Upsilon
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Looks promising, though I do not currently have a powerful source of UV light. That's assuming that sunlight or a common blacklight aren't enough to
make it work.
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careysub
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One might contemplate using CaF2 in one-pot syntheses where HF is produced and consumed in situ, with suitable precautions to dowse residual HF in the
flask, and traps to prevent its escape as vapor.
Of course many of the products you might prepare this way are typically volatile fluorides (SiF4, BF3) that may hydrolyze releasing HF again. SiF4
does in part, at any rate.
Volatile fluorides are just bad news (not even Teflon is safe, if pyrolyzed).
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