DFliyerz
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Iron (III) Source
While doing some experiments with ferrates, I've found that FeCl3 can be extremely difficult to crystallize for use in preparing ferrates. I was
wondering if anyone knew another soluble and easily crystallized source of iron (III), or how to crystallize ferric chloride effectively.
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blogfast25
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Ferric ammonium alum is one of the stablest Fe(+3) compounds and relatively easy to prepare and crystallise:
https://en.wikipedia.org/wiki/Ammonium_iron(III)_sulfate
There are a few threads on its synthesis on SM.
[Edited on 3-9-2015 by blogfast25]
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aga
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If you're going to be using it in aqueous solution, may as well leave it aqueous.
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DFliyerz
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I suppose, but that can easily mess up the stoichiometry.
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gdflp
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If you're worried about knowing the exact concentration of ferric ions, why not just titrate your solution? The concentration shouldn't significantly
change over time as long as there are no ferrous ions present, so you only need to titrate one sample. An EDTA titration would likely be the easiest
for you to perform as it doesn't require any difficult to obtain indicators or titrants. See a step by step procedure here.
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aga
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Measure how much Iron or HCl you use ?
Titration even ?
If you give anhydrous FeCl3 even a whiff of moisture then your exact weights will be out anyway.
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blogfast25
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Quote: Originally posted by aga  |
If you give anhydrous FeCl3 even a whiff of moisture then your exact weights will be out anyway. |
Sure but anhydrous FeCl3 has nothing to do with anything here.
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aga
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My point was simply that attempting to make dry ferric chloride (in order to weigh it) is very difficult and largely pointless if it is intended for
use in an aqueous solution.
Edit :
As a challenge/exercise, well worth attempting.
[Edited on 3-9-2015 by aga]
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MrHomeScientist
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Even so, it does decompose over time if left out, as I found out the hard way! My beautiful purple crystals, left in the back of a fume hood, crumbled
into a tan powder after about a year 
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aga
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Nothing lasts forever.
Use it or lose it is the way it goes.
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