guy
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Help Making Ferric chloride from electrolysis
I have been trying to make ferric chloride by electrolysis. I used a saturated solution of NaCl in water and Fe anode seperated by a paper towel salt
bridge. I used a 6V lantern battery. Instead of getting FeCl3, it was just insoluble Fe(OH)3. Why did this happen?
Also when I tried to make CuCl2 with the same set up, I got CuCl.
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JohnWW
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Hydrolysis. Fe+++ is very easily hydrolysed to Fe(OH)3 in aqueous solution, except in strongly acid solutions. Only with strong non-complexing acids
like H2SO4 and HClO4 is the orange-yellow Fe(H2O)6+++ cation able to be obtained reasonably pure. Cl- ion with an excess of HCl would produce the
FeCl4- ion, in equilibrium with Fe(H2O)6+++ depending on Cl- concentration and pH.
You would probably do better dissolving Fe turnings in an excess of HCl.
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guy
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Why wouldn't the Fe(OH)3 react with the HCl again? I'm beginning to think maybe the NaCl speeds uo the oxidation of Fe to Fe2O3.
What about the copper chloride? If I can manage to make CuCl2 maybe I can displace the Cu with Fe to make FeCl3.
[Edited on 10 / 6 / 8 by guy]
[Edited on 10 / 6 / 8 by guy]
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darkflame89
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Just how much insoluble iron(III) hydroxide did you get? As stated by JohnWW, Fe(OH)3 is formed due to an equilibirium equation. Too much acid, and no
insoluble products is formed.
Iron(III) hydroxide would only react back with the HCl formed when the pH is too low below a certain value.
You can't have had too much of the insoluble product, did you? Was your anolyte at least yellowish brown?
Ignis ubique latet, naturam amplectitur omnem.
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guy
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Just a little bit. I guess there is an equililibrium between the Fe(OH)3 and FeCl2. I mixed the NaOH side and got a green precipitate so I guess I
am currently having a FeCl2.
Is there also a way to make Cu(II) chloride using electrolyis, I keep getting Cu(I)Cl.
[Edited on 10 / 6 / 8 by guy]
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darkflame89
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You sure it's CuCl? CuCl is quite unstable. You might be just getting basic CuCl2 , which appears green too. I tried this with copper anode
before, at a certain voltage, green insoluble stuff was generated too.
Ignis ubique latet, naturam amplectitur omnem.
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guy
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What do you mean basic CuCl2? There were no -OH or any basic anions present, its seperated by a salt bridge. I keep getting an initially green then
blue crystllization at the surface which was insoluble.
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Theoretic
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You could be, in fact, getting a very fine suspension of Cu(OH)2
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guy
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| Quote: |
You could be, in fact, getting a very fine suspension of Cu(OH)2
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Please tell me how I can get Cu(OH)2 when there was no way for the -OH ions to contact the Cu++ ions?
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BromicAcid
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A salt bridge does allow for the passage of some ions along it, however there is always the autodissociation of water, but then again I'm trying
to justify something that I've never attempted.
Personally to get ferric chloride I would take some HCl and add iron filings to it, then preform electrolysis on it with iron electrodes. Any
hydrated iron oxides formed will instantaneously react away so the oxidation of the ferrous cation can continue normally.
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