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Topic: Fluorite  (Read 5314 times)

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Offline SpontaneousRxn

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Fluorite
« on: November 14, 2007, 02:54:45 AM »
Hello everyone!
I just have a really quick question.  For my general chemistry class, we were asked to synthesize calcium fluorite using calcite, villaumite and hydrochloric acid only.  I got my reactions to get to the calcium fluorite part.  My question is, what kind of reactions are they?
These are my rxns:
CaCo3 + 2HCl -> CaCl2 + CO2 + H2O

CaCl2 + 2NaF -> CaF2 + 2NaCl

Is it precipitate? Acid base???
I am just clueless....

Thanks for any input 

Offline shelanachium

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Re: Fluorite
« Reply #1 on: November 14, 2007, 08:43:19 AM »
The first reaction is acid/base, or more specifically decomposition of a carbonate by an acid. Carbonic acid H2CO3 is weak, so readily displaced by the much stronger acid HCl; it is also spontaneously unstable, decomposing to water and carbon dioxide, which escapes as gas:

CaCO3 + 2HCl -> CaCl2 + [H2CO3]

[H2CO3] -> H2O + CO2 (gas)

The second reaction is a 'double decomposition' which occurs when a solution contains ions any of which can combine to form a salt of low solubility. NaF and CaCl2 are both soluble in water, NaF giving Na+ and F- ions, and CaCl2 gives Ca2+ and F- ions. When the solutions are mixed, the Ca2+ and F- ions form insoluble CaF2 as a precipitate. The Na+ and Cl- ions remain in solution as sodium chloride is soluble in water.

Offline shelanachium

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Re: Fluorite
« Reply #2 on: November 14, 2007, 08:45:06 AM »
Woops. Missed a typo. CaCl2 of course gives Ca2+ and Cl- ions not F-!

Offline SpontaneousRxn

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Re: Fluorite
« Reply #3 on: November 15, 2007, 12:50:10 AM »
thank you so much!!! ;D

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