Chemistry_Keegan
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Will This Reaction Occur
So I managed to make some sodium aluminate and some iron three chloride. I would like to mix the two chemicals to create aluminium hydroxide and iron
three hydroxide, but I am not sure if it is possible. So I was wondering, is this chemical equation really correct:
FeCl3 + 3 NaAlO2 + 6 H2O = Fe(OH)3 + 3 Al(OH)3 + 3 NaCl
If not, does something different happen, or maybe nothing at all?
[Edited on 18-2-2013 by Chemistry_Keegan]
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woelen
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What will happen is formation of a red/brown precipitate, which will have a complicated non-stoichiometric constitution. It can be written as
xFe2O3.yAl2O3.zH2O, but the precise ratio of x, y, and z cannot be told beforehand. In reality there will be hydroxo-groups, oxo-groups and more
complicated bridging structures in the precipitates. As impurity there almost certainly will also be some sodium ions and chloride ions in the
precipitate, which may be very hard to rinse away.
So, you certainly will get a precipitate which can be considered a mixed iron(III)/aluminium hydroxide, but do not expect to get anything pure.
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Hexavalent
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If one filtered the precipitate and added aqueous sodium hydroxide, woelen, would separation of the hydroxides be feasible? Aluminium, being
amphoteric, should re-dissolve in base to give sodium aluminate whereas the iron would remain as the insoluble hydroxide.
Any thoughts?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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blogfast25
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Quote: Originally posted by Hexavalent  | If one filtered the precipitate and added aqueous sodium hydroxide, woelen, would separation of the hydroxides be feasible? Aluminium, being
amphoteric, should re-dissolve in base to give sodium aluminate whereas the iron would remain as the insoluble hydroxide.
Any thoughts? |
Yes, that works. It's a primary way to separate iron and aluminium. See e.g. the Bayer process for the purification of Bauxite (Al2O3 with Fe2O3
impurity).
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AJKOER
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Actually, in my opinion the best answer depends on the circumstances (who is asking). If this is a purely academic question and you are not in an
advanced college chemistry course, your original answer is probably the way to go. In a lab or for someone who really wants the real answer, then
Woelen's answer is best. More advanced academic setting, Woelen is probably the better bet.
Generally speaking in my opinion (please pardon my philosophical sidebar), there are at least 3 possible best answers, which are not necessarily
distinct, to any question.
First, there is the absolute truth. This may currently been an obscure theory or not even a widely accepted position, or completely unknown.
Second, there is the current most widely held (the statistical mode) opinion among experts, or perhaps the average or median position on a more
quantitative question.
Third, there is the most appropriate answer for the context. For example, in an educational testing environment, there is the best answer among
presented choices, or a good approximation of the truth (or, an incomplete version) that is understandable at the student's (or audience's) level. In
essence, a transformed view of reality for a particular purpose. For example, this may also be the most popular opinion among a wider audience of not
quite experts.
[Edited on 19-2-2013 by AJKOER]
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Chemistry_Keegan
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So what would I be left with if I evaporated all the water away?
[Edited on 24-2-2013 by Chemistry_Keegan]
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blogfast25
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At which point are you planning to evaporate the water?
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AndersHoveland
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It is not really relevant here, but I think Fe(OH)3 can slowly be dissolved with excess NaOH if air is passed into the solution. The iron gets
oxidized to soluble Na2FeO4.
Cu(OH)2 is also slightly amphoteric. Both these instances require a strong solution of NaOH. Sodium carbonate is not alkaline enough.
I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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elementcollector1
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| Quote: Originally posted by AndersHoveland | It is not really relevant here, but I think Fe(OH)3 can slowly be dissolved with excess NaOH if air is passed into the solution. The iron gets
oxidized to soluble Na2FeO4.
Cu(OH)2 is also slightly amphoteric. Both these instances require a strong solution of NaOH. Sodium carbonate is not alkaline enough.
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1) Nope, not strong enough oxidizer. You may be thinking of bleach. I've tried ferrate from Fe(OH)3 with just NaOH, and it did nothing.
2) Interesting, but irrelevant for now.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Lambda-Eyde
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| Quote: Originally posted by AndersHoveland | | It is not really relevant here, but I think Fe(OH)3 can slowly be dissolved with excess NaOH if air is passed into the solution. The iron gets
oxidized to soluble Na2FeO4. |
I highly doubt that oxygen is a strong enough oxidant to oxidize Fe(III) to ferrate...
This just in: 95,5 % of the world population lives outside the USA
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AndersHoveland
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Under very alkaline conditions, many elemental oxides become vulnerable to being further oxidized by air. NO2 and SO2 can both be further oxidized
under alkaline conditions, for example.
While ferrate may be a very powerful oxidizer while being acidified and decomposing, it is a much weaker oxidizer under alkaline conditions, with a
reduction potential of only 0.72v, this value is even less than Fe+3 (0.77v) !! And we all know that Fe+2 salts can gradually be oxidized
in the presence of air.
[Edited on 25-2-2013 by AndersHoveland]
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woelen
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I have done quite a few experiments with production of ferrates from Fe(OH)3 and the only oxidizers I found, capable of producing ferrate, are
hypochlorite and peroxodisulfate, both at very high pH and only slowly. Some heating was required as well and at the same time, this leads to
decomposition of much of the oxidizer. Hydrogen peroxide did not do the job. I also never noticed oxidation by air, while I did the experiments in
contact with air under constant shaking and swirling.
The same is true for production of permanganate from hydrous MnO2. This does not occur with air, but it does so with hypochlorite.
My experiments of course do not imply that there are no other oxidzers, capable of producing ferrates from Fe(OH)3, but they do show that really
strong oxidizers are needed and that oxidation by oxygen from air is not a viable route to ferrates in aqueous solution.
Maybe it is possible to make ferrates by passing oxygen through a molten mix of Fe(OH)3 and NaOH.
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blogfast25
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Acc. A.F.Holleman such a fusion/oxidation to Fe VI requires nitrate or chlorate to make it work. Most of the ferrate VI will fall apart when you try
and leach it out though.
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Eddygp
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Could sodium ferrate be formed with an oxidizer similar to sodium permanganate or ozone, for example? I think that ferrates are very interesting ions,
and I had thought about using NaOH, KMnO4 and Fe2O3 (or the hydroxide) in order to synthesize some. Apart from this, I don't know if it would be
possible to create a tetraoxoferrate(VI) from a hexacyanoferrate(II) or a hexacyanoferrate(III) compound, but it would certainly be interesting... it
would probably need a fairly oxidizing agent, and the (CN)2 or HCN fumes wouldn't be too pleasant.
[Edited on 24-3-2013 by Eddygp]
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Chemistry_Keegan
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After I mix the sodium aluminate solution and the ferric chloride solution.
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