Alchemic
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Crystallization of Iron(II) sulfate
Hi!
I have a mixed solution of Sodium Sulfate and Iron sulfate.
It to would be nice to separate them and to crystalize just an Iron sulfate.
I had a look at solubility and unfortunattely it is very close for both instances.
Is there any ideas how to crystalise just an Iron sulfate?
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Hegi
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Quote: Originally posted by Alchemic  | Hi!
I have a mixed solution of Sodium Sulfate and Iron sulfate.
It to would be nice to separate them and to crystalize just an Iron sulfate.
I had a look at solubility and unfortunattely it is very close for both instances.
Is there any ideas how to crystalise just an Iron sulfate? |
OK. I would try........ Add an excess of sodium hydroxide solution to your mixture. The precipitate of Iron(II) hydroxide will form. Filter it off as
quickly as you can and wash it with huge amount of water to get a rid of sodium sulfate and hydroxide. Transfer the precipitate to the beaker and add
sulfuric acid to dissolve it (in excess and also some iron nails to reduce oxidized iron atoms). Should work.
Our webpage has been shut down forever cause nobody was willing to contribute. Shame on you all!!!
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annaandherdad
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For fractional crystallization, you need to pay attention to the fraction of each substance present, in addition to the solubilities. For example,
in sea water the calcium sulfate crystallizes first (low solubility, low concentration), then sodium chloride (moderate solubility, less than that of
some other ingredients, but present at 90% mass fraction). Then at a later point you get magnesium chloride and other things, that you can separate
mechanically because the crystal structures are so different. But to get pure compounds requires multiple crystallizations and it involves some
loss.
So, in your case, what are the percentages of sodium sulfate and iron II sulfate? Also note that the crystals of each are of different colors, and it
might be possible to separate them mechanically.
Any other SF Bay chemists?
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Alchemic
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| Quote: Originally posted by Hegi | | Quote: Originally posted by Alchemic | Hi!
I have a mixed solution of Sodium Sulfate and Iron sulfate.
It to would be nice to separate them and to crystalize just an Iron sulfate.
I had a look at solubility and unfortunattely it is very close for both instances.
Is there any ideas how to crystalise just an Iron sulfate? |
OK. I would try........ Add an excess of sodium hydroxide solution to your mixture. The precipitate of Iron(II) hydroxide will form. Filter it off as
quickly as you can and wash it with huge amount of water to get a rid of sodium sulfate and hydroxide. Transfer the precipitate to the beaker and add
sulfuric acid to dissolve it (in excess and also some iron nails to reduce oxidized iron atoms). Should work. |
Thanks for the "recipie" but makes not too much sense - it would be same thing if to discard the whole solution and to start etching rusty nails....
it would save at least one reagent (base) and less acid will be used
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DraconicAcid
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Fractional crystallization assumes that a mixed salt such as Na2Fe(SO4)2 doesn't form. That might not be a good assumption.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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annaandherdad
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Yes, that's true, and I certainly don't know if it does, but if you just evaporate some and find crystals of two different colors, it probably means
that you have separated sodium and ferrous sulfates.
Any other SF Bay chemists?
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Texium
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Thread Moved
23-3-2016 at 12:40 |
Hegi
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| Quote: Originally posted by Alchemic | | Quote: Originally posted by Hegi | | Quote: Originally posted by Alchemic | Hi!
I have a mixed solution of Sodium Sulfate and Iron sulfate.
It to would be nice to separate them and to crystalize just an Iron sulfate.
I had a look at solubility and unfortunattely it is very close for both instances.
Is there any ideas how to crystalise just an Iron sulfate? |
OK. I would try........ Add an excess of sodium hydroxide solution to your mixture. The precipitate of Iron(II) hydroxide will form. Filter it off as
quickly as you can and wash it with huge amount of water to get a rid of sodium sulfate and hydroxide. Transfer the precipitate to the beaker and add
sulfuric acid to dissolve it (in excess and also some iron nails to reduce oxidized iron atoms). Should work. |
Thanks for the "recipie" but makes not too much sense - it would be same thing if to discard the whole solution and to start etching rusty nails....
it would save at least one reagent (base) and less acid will be used |
You asked for the method  But anyway, you are right, discard it and make a new or
buy one.
Our webpage has been shut down forever cause nobody was willing to contribute. Shame on you all!!!
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pesco
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| Quote: Originally posted by Alchemic | Hi!
I have a mixed solution of Sodium Sulfate and Iron sulfate.
It to would be nice to separate them and to crystalize just an Iron sulfate.
I had a look at solubility and unfortunattely it is very close for both instances.
Is there any ideas how to crystalise just an Iron sulfate? |
Direct separation is impossible, but you can get something out of it anyway.
Boil the mixture.
To oxidize iron(II) sulphate to iron(III) sulphate add some H2SO4 (you'll recover it later) and H2O2. If
you don't want to use peroxide aerating hot solution should work as well.
Insoluble jarosite will drop according to reaction :
Na2SO4 + 3 Fe2(SO4)3 +12 H2O = 2
NaFe3(SO4)2(OH)6 + 6 H2SO4
Make sure there is enough sodium sulphate in the mixture or not all Iron would drop.
Once that done, filter off jarosite and you have mix of very useful chemicals -> Na2SO4 and H2SO4.
Once separated the later you can use to dissolve some rusty nails.
Some losses are present in form of jarosite, but better that than discarding the whole mess.
Regards
[Edited on 30-3-2016 by pesco]
[Edited on 30-3-2016 by pesco]
[Edited on 30-3-2016 by pesco]
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crystal grower
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Do not forget na2so4 in acidic enviroment ----> NaHSO4.  .
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pesco
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Well pointed out grower.
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