[greeneyedcritter]

Hello,

For a Gen. Chem. (I) project, I need to synthesize flourite using only these available minerals: Calcite (calcium carbonate), Villiaumite (sodium fluoride), also available are HCl and water. Apparently, I should be able to do this in two Rx's. CaCO3 is insoluble in water but does react with weak acids. NaF is soluble in water. So I have concluded that I need to react CaCO3 with the HCl and NaF with H2O. But I am unsure of what state the products will be and what type of reactions took place (Precipitation, Aqueous, Neutralization). Also unsure of how to isolate CaF2 (flourite) after these steps.

Possible chemical equations so far:

1. CaCO3(s) + HCl(aq) --> CaCl(soluble salt) + HCO3(g?)
or
2. NaF(s) + H2O(aq) --> NaO(?) + HF(acid, state ?)
then
3. CaCO3 + HF --> CaF(ppt?) + HCO3(g)
or
4. NaF + HCl --> NaCl (soluble salt) + HF
then
#3 above

Of course isolating the CaF2 is still a mystery to me after I get the reaction. Since CaF2 is insoluble it should form as a ppt right?
As you can see I'm not sure what route to go. Any hints or insights would be appreciated.

Thanks,

greeneyedcritter

[AWK]

CaCO3(s) + 2HCl(aq) = CaCl2(aq) + CO2(g) + H2O
then add stoichiometric amount of NaF to this solution
CaCl2(aq) + 2NaF(s) = CaF2(s) + 2NaCl(aq)

[greeneyedcritter]

Wow, thanks that was quick. I think I had too much info in my brain and couldn't break it down.

So the ppt CaF2 will be left at the bottom. How do I separate the NaCl and CaF2? Just pour NaCl(aq) out?

gec

[hmx9123]

AWK has the right equations for you.  What happens is that you have calcium chloride in solution.  Take a look through the CRC Handbook of Chemistry and Physics.  My HS a bunch of copies; your university chemistry library undoubtedly will as well--check the reserve or reference sections.  Anyway, check out the solubilities of the compounds in question.  You'll find that calcium chloride and sodium chloride are highly soluble in water at room temperature.  Calcium fluoride is not.  What this means in terms of watching the reaction is this:

You have a white powder (calcium carbonate) in a beaker.  You add HCl.  Lots of bubbles form (carbon dioxide) and the material dissolves.  You now have a clear solution that looks like water.  Add your NaF to this (you might want to do this in a hood as there may be a small amount of HF that comes off) and stir.  The sodium fluoride will dissolve and then a white solid will precipitate.  If you want to dissolve the NaF in water and add this solution, that should work as well.  The white solid that precipitates is CaF₂.  Since sodium chloride is soluble in water, it will remain behind in solution.  You only need filter the calcium fluoride and then wash it with some water.  Dry it, and you have calcium fluoride.

[greeneyedcritter]

I was able to go over the subject today with a classmate. Put our heads together, you know. Thanks for the help.

 

gec