veerenyadav
Harmless
Posts: 30
Registered: 1-3-2014
Member Is Offline
Mood: No Mood
|
|
Ferric oxalate to ferrous oxalate
how to convert ferric oxalate into ferrous oxalate
|
|
|
gdflp
Super Moderator
Posts: 1320
Registered: 14-2-2014
Location: NY, USA
Member Is Offline
Mood: Staring at code
|
|
Firstly you should be more specific about your question. Secondly, this belongs in Beginnings not Organic Chemistry. To convert it, dissolve the
ferric oxalate in water, add an equivalent stoichometric amount of sodium hydroxide, then bubble hydrogen gas through the mixture, the ferrous oxalate
will precipitate out. The balanced equation is Fe2(C2O4)3 + 2NaOH + H2 -->
FeC2O4 + Na2C2O4 + 2H2O
|
|
|
woelen
|
Thread Moved
20-5-2014 at 11:25 |
woelen
Super Administrator
Posts: 8014
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Are you sure that bubbling hydrogen through the solution does the reduction? I strongly doubt it, actually I can hardly believe this. Hydrogen gas is
quite inert and does not easily react with oxidizers in aqueous solution. Maybe this reaction with ferric oxalate is a rare exception, but if this
indeed is the case, then I would like to see from where you have this information, or experimental evidence.
|
|
|
CHRIS25
National Hazard
Posts: 951
Registered: 6-4-2012
Location: Ireland
Member Is Offline
Mood: No Mood
|
|
Ah photography knowledge here - ferric oxalate can decompose to ferrous oxalate through sunlight. Faster still use a UV lamp.
‘Calcination… is such a Separation of Bodies by Fire, as makes ‘em easily reducible into Powder; and for that reason ‘tis call’d by some
Chymical Pulverization.’ (John Friend, Chymical Lectures London, 1712)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. (William Penn 1644-1718)
The very nature of Random, Chance development precludes the existence of Order - strange that our organic and inorganic world is so well defined by
precision and law. (me)
|
|
|
gdflp
Super Moderator
Posts: 1320
Registered: 14-2-2014
Location: NY, USA
Member Is Offline
Mood: Staring at code
|
|
This page gives a reduction potential of -0.83 for the reaction 2H2O + 2e- --> H2 + 2OH-. I would assume from this that the reaction would occur
since it has a negative delta G.
|
|
|
woelen
Super Administrator
Posts: 8014
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Reduction potential only tells something about the energy needed for (or released by) a reaction. It does not tell anything about a mechanistic
pathway for the reaction to occur. So, energetically, a reaction may be favorable, but it might be that in reality the reaction needs a large
activation energy.
A nice example is combustion of wood. This is a highly exothermic process, but it does not occur spontaneously. First, some activation energy must be
supplied. Usually this is done by heating part of the wood and the heat of the reaction then is the activation energy for other parts of the wood
(activation energy is not lost, it is returned after the reaction), so the net effect is highly exothermic.
With H2 I expect the same. I do not expect it to react just by bubbling through the solution. You need some activation energy (heat, intense
radiation), or you need to modify the mechanistic pathway for the reaction (suitable catalyst) such that its activation energy is lowered.
|
|
|
veerenyadav
Harmless
Posts: 30
Registered: 1-3-2014
Member Is Offline
Mood: No Mood
|
|
Thanks all, but
Actually, I have ferric oxalate green solution. Addition of NaOH add one more compund in solution that is sodium oxalate. I want pure ferrous oxalte
to precipitate.
I used UV or sun light but it is a bit slow and do not have any idea about its commericla scale application. So searching some reducing agnet which
should not add any impurity in ferrous oxalate like H2O2 for oxidation.
So, suggest some thing which can help me.
|
|
|
veerenyadav
Harmless
Posts: 30
Registered: 1-3-2014
Member Is Offline
Mood: No Mood
|
|
Thanks all, but
Actually, I have ferric oxalate green solution. Addition of NaOH add one more compund in solution that is sodium oxalate. I want pure ferrous oxalte
to precipitate.
I used UV or sun light but it is a bit slow and do not have any idea about its commericla scale application. So searching some reducing agnet which
should not add any impurity in ferrous oxalate like H2O2 for oxidation.
So, suggest some thing which can help me.
|
|
|
gdflp
Super Moderator
Posts: 1320
Registered: 14-2-2014
Location: NY, USA
Member Is Offline
Mood: Staring at code
|
|
Sodium oxalate is soluble in water and ferrous oxalate is insoluble, so the two are very easy to separate. Just filter and wash with water, there
will be no measurable residual sodium oxalate left.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by gdflp  | | This page gives a reduction potential of -0.83 for the reaction 2H2O + 2e- --> H2 + 2OH-. I would assume from this that the reaction would occur
since it has a negative delta G. |
I even doubt that it has a negative Delta G because I'm pretty certain you were looking at the reduction potential for Fe<sup>3+</sup> + e
===> Fe<sup>2+</sup>.
But here the iron (III) is present as trisoxalato ferrate (III), a complex. Complexes are much harder to reduce, depending on complexation (formation)
constant, because it [the complexation] adds an endothermic term to the Delta G calculation.
And as woelen said: a negative Delta G still wouldn't prove the reaction would be practical. Hydrogen gas is pretty inert at RT.
[Edited on 21-5-2014 by blogfast25]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
