Yttrium2
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HF production question
In Gen chem 1 I remember learning some like how the more electronegative anion will displace the anion with lower electronegativity. We saw color
changed when mixing certain hydrohalogens, if I remember correctly.(is this correct) Well, anyways I'm wondering when
CaF2 is added to H2SO4,
how come the fluorine atoms combine with the hydrogen?
Haven't reviewed my notes for a while
[Edited on 6-10-2015 by Yttrium2]
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Yttrium2
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Does it have to do with the atomic radius? The smaller the more stronger the bond?
Wish I haven't forgotten so much.
Yikes
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DalisAndy
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I think it's because of the fact most metal salt will recombined with another anion up to a point, using la chatelier's princple. I know copper(II)
sulfate will recombined with HCl, to form some copper(II) chloride
Elements Collected: 19/81 (Excluding all radioactive, using placecard for those)
Any tips or good sources are welcome.
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Darkstar
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First of all, the CaF2 is technically in equilibrium with HF:
CaF2 + H2SO4 ⇌ 2 HF + CaSO4
Second of all, this reaction is not carried out at room temperature, but at temperatures upwards of 300 °C. Since HF boils at around 20 °C, it
quickly leaves the reaction vessel as a gas once it forms. This shifts the equilibrium far over to the right to favor HF production.
The overall reaction looks like this:
CaF2(s) + H2SO4(l) → 2 HF(g) + CaSO4(s)
And yes, the bond between hydrogen and fluorine is extremely strong since the fluoride ion is so tiny. Due to its size, the negative charge on
fluoride is distributed over a small area making it extremely strong. This is one of the reasons that hydrofluoric acid is a weak acid. (it also has
to do with its interaction with water molecules, though)
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