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Chemical substance found in Fluorite

Posted by FluoriteGuy  
Chemical substance found in Fluorite
October 10, 2011 11:22PM
I need to come up with a source of the chemical substance found in fluorite. I was wondering if anyone had any chemical knowledge on how to convert villiaumite and calcite, to the chemical substance (found in fluorite), using water and hydrochloric acid.

I was wondering if you could provide a detailed description of how we can prepare the desired chemical substance using these materials.

Confused student,
Thank you
avatar Re: Chemical substance found in Fluorite
October 11, 2011 02:10AM
chemically, fluorite is calcium fluoride (CaF2) and villiaumite is sodium fluoride (NaF). It is possible to break down both into their elemental components, but I would strongly recommend against trying. Both will liberate fluorine gas, which is EXCEEDINGLY TOXIC. Elemental calcium and sodium are also very reactive and flammable in the presence of water.
Re: Chemical substance found in Fluorite
October 11, 2011 02:17AM
It's not completely clear what he/she wants to do, but my impression was they want to synthesize fluorite from calcite and NaF, in which case they just need to dissolve the calcite in any weak acid and then add the villiaumite, or a villiaumite solution in water? Nothing dangerous, unless they drink the leftover villiaumite.
avatar Re: Chemical substance found in Fluorite
October 11, 2011 11:27AM
The way I think of it. Dissolve "appropriate" amount of NaF (villiaumite) and CaCO3 in a "sufficiently" acidous solution of HCl. If all goes well and you've done your calculations right the result would/should be solid CaF2, saltwater and some gaseous CO2.
Long time ago since I did any chemistry so please don't hold this against me.

Re: Chemical substance found in Fluorite
October 11, 2011 03:49PM
Thanks for the help! I'm sorry if i was a little unclear, but your responses have answered my question perfectly. Now time to experiment!
avatar Re: Chemical substance found in Fluorite
October 12, 2011 05:08AM
Fluorite guy,
Where did you get your villiaumite?

Rock Currier
Crystals not pistols.
Re: Chemical substance found in Fluorite
October 13, 2011 12:38AM
I need to first disassociate the Calcite molecules with a solution of HCl:

CaCO3(s) + 2HCl(aq) --> CaCl2(aq) + CO2(g) + H2O(l)

With the products shown, I can then add them to Villiaumite in the equation:

CaCl2(aq) + CO2(g) + H2O(l) + 2NaF(aq) --> CaF2(s) + 2NaCl(aq) + CO2(g) + H2O(l)

With my solution i can wait until it precipitates and then vacuum filter in and catch the precipitant on filter paper.
avatar Re: Chemical substance found in Fluorite
May 26, 2012 05:07AM
Since the solubility of CaF2 is not that low as it would appear from a cursory look at the solubility product (note the stoichiometry), you also need to consider that a certain amount of fluoride will stay in solution. This can be considerable if you are working with small amounts of sample in a large volume of solution (i.e. at low concentration). Increasing the concentration too much may turn out to be counter-productive as well, since the amount of impurities will incorporated in the lattice of your CaF2 precipitate will increase with concentration.
avatar Re: Chemical substance found in Fluorite
May 26, 2012 09:02AM
The Mindat data page for Villiaumite has this to say about the substance, so I would say it is not something to be casually messing with.

Poisonous! May be fatal if swallowed or inhaled. Affects respiratory system, heart, skeleton, circulatory system, central nervous system and kidneys. Causes irritation to skin, eyes and respiratory tract. Irritation effects may be delayed.


United Kingdom, Cornwall
avatar Re: Chemical substance found in Fluorite
May 26, 2012 06:11PM
I admit NaF MSDS is really scary but yet they put this thing in chewalble NaF tablets for preventing tooth cavities and fluoride toothpastes (0.32% fluoride!).
Re: Chemical substance found in Fluorite
May 26, 2012 08:19PM
Years ago, the MSDS for water used to say that it was toxic and - if ingested - treatment should be to give the casualty plenty of water to drink. confused smiley. Thankfully, they've amended that now.


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