CHRIS25
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Confusion about synthesizing Ferric Oxalate
First Problem:
The last step for making Ferric Oxalate is: 2FeCl3 + 6H2C2O4 +3H2 = 2Fe(C2O4)3 + 6HCl: I do not understand where I get the 3H2 from, I mean I have
no access to Hydrogen? Sorry just realised that the H ions will be supplied by the water.
Second Problem:
Step 1 - Fe + 2HCl = FeCl2 + 2H
Step 2 - FeCl2 + H2C2O4 = FeC2O4 + 2HCl
But this is Ferrous Oxalate not Ferric. So should I leave the FeCl2 from step 1 to turn into FeCl3 through the action of the oxygen in the air before
proceeding further, or add H2O2 first before proceeding with step 2?
Then I presume that I will have my FeCl3 in order to proceed?
[Edited on 14-1-2013 by CHRIS25]
‘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)
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bbartlog
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Where did you get the first equation? It's not balanced, which looks to be the most likely source of your confusion. Seems like it should be
2FeCl3 + 3H2C2O4 -> Fe2(C2O4)3 + 6HCl
...assuming that the reaction proceeds, for whatever reason; I'm just shuffling around numbers and using valences to balance your equation properly,
not saying that this is what happens.
The less you bet, the more you lose when you win.
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CHRIS25
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Just checked - you are right; don't know where I got that from, messed it up. My notes are quite a shambles right now. But the second part of my
problem still remains unfortunately. I mix steel wool with HCl according to the stoichemetry to get the Ferrous chloride. So to get the ferric
chloride I just let it stand or add H2O2? I do not want to add H2O2 to Ferrous oxalate since I am wanting to get the powder Ferric oxalate. So I am in
need of some pointers here as to the best way to synthesize this. I also know that I can begin with Ferric ammonium sulphate and ammonium in the form
of ammonium hydroxide but this process is too messy.
‘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)
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Vargouille
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You can just begin with a ferric salt. Ferric sulfate and ferric chloride shouldn't be too difficult to find. Otherwise, starting from ferrous
chloride, you can slowly add a slight excess of H2O2 (to account for decomposition), heat gently to decompose any remaining H2O2, and proceed from
there. If I remember correctly, the oxidation of ferrous ion is significantly exothermic. If you want a fool-proof way, you can just leave it for a
week and the ferrous ion will be oxidized to ferric.
[Edited on 14-1-2013 by Vargouille]
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CHRIS25
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Thankyou Vargouille.
[Edited on 15-1-2013 by CHRIS25]
‘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)
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CHRIS25
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I have been reading Woelen's site on the oxidation states of Iron again. Amongst the other references I have been reading I keep reading about being
careful to avoid the Hydrolysis of Ferric chloride as you are making it. Now please could somebody confirm the following: To avoid breaking down the
Ferric chloride into its hydroxide state I presume I have to keep the HCl amount above the stoichemetry amounts. IE, I have used three timer the
amount of 11m HCl. Also, I am heating the reaction gently. Is this ok? I am aiming to make ferric chloride hexahydrate, since this will be the only
way I can be assured of getting a reasonable pure grade of ferric chloride.
[Edited on 15-1-2013 by CHRIS25]
‘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)
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Vargouille
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Heating gently should be fine, with a large excess of acid, of course. Heating it gently is fine, just don't heat it to dryness. Once it's very
concentrated, leave it to evaporate.
EDIT: That large of an excess of HCl should be fine.
[Edited on 15-1-2013 by Vargouille]
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CHRIS25
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Quote: Originally posted by Vargouille  | Heating gently should be fine, with a large excess of acid, of course. Heating it gently is fine, just don't heat it to dryness. Once it's very
concentrated, leave it to evaporate.
EDIT: That large of an excess of HCl should be fine.
[Edited on 15-1-2013 by Vargouille] |
Once again thankyou for the reply.
‘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)
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AJKOER
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Here is an interesting path to FeCl3. By the action of HOCl on Fe, or by the action of Fe(OH)3 with HOCl and HCl (or Chlorine water, see Mellor http://books.google.com/books?id=7XoGAQAAIAAJ&pg=PA275&a...):
Fe(OH)3 + 3 HOCl + 3 HCl ---> Fe(ClO)3 + 3 HCl + 3 H2O
However, Ferric hypochlorite is not stable (exists?) quickly decomposing into HOCl and FeCl3 via:
Fe(ClO)3 + 3 HCl --> FeCl3 + 3 HOCl
Note, per Mellor page 275 one can substitute a suspension of Fe2O3 for Fe(OH)3.
HOCl can be prepared by the action of a weak acid (including vinegar, ascorbic, citric or even H2CO3, but the latter reaction is slow) on NaOCl.
A path to rust: the action of carbon dioxide, water and oxygen on iron:
Fe + 2 CO2 + 2 H2O ---> Fe(HCO3)2 + H2 (g)
and with air in time:
2 Fe(HCO3)2 + 1/2 O2 + H2O ---> Fe(OH)3 + 4 CO2
Note also the action of O2 on FeCl2 makes both Fe2O3 and FeCl3:
12 FeCl2 + 3 O2 --> 8 FeCl3 + 2 Fe2O3
Also, the action of HOCl or NaOCl on Fe:
NaOCl + Fe --> NaCl + FeO
and as noted by Mellor:
2 FeO + HOCl --> Fe2O3 + HCl
[Edited on 17-1-2013 by AJKOER]
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CHRIS25
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Thankyou AJkoer, I read this on another part of this forum I think and found it informative. I think I heated gently for too long because this
morning, two days later, I found precipitated rust, this iron oxide indicates that I have exhausted the HCl content in solution I 'think'; Also I
understand that this rust is a mixture of Iron 3 and 2, which indicates an exhaustion of free HCl I presume. So not wanting to end up with the
hydroxide in solution I added more 36% HCl this morning. There is still steel wool in the solution about 10% of the 5.5 grams left. This assures me
that I still have FeCl2 and hopefully tells me that my FeCl2 is fairly concentrated as it is unable to oxidize at the moment which is where I want it
before proceeding to stage 2. Am I getting my facts right here please?
[Edited on 18-1-2013 by CHRIS25]
‘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)
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Vargouille
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Why should the rust be a mixture of ferrous and ferric oxides? As far as I know, that's magnetite, which is instantly distinguishable from Fe2O3
because FeO-Fe2O3 is black, while Fe2O3 is red. An exhaustion of HCl would only result in production of Fe2O3. As for the FeCl2 concentration, you are
correct, but as for how concentrated the ferrous ion is, that'll take a calculation to find out.
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CHRIS25
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| Quote: Originally posted by Vargouille | | Why should the rust be a mixture of ferrous and ferric oxides? As far as I know, that's magnetite, which is instantly distinguishable from Fe2O3
because FeO-Fe2O3 is black, while Fe2O3 is red.. |
Hi, nice to see you again, so to speak. I remember
reading sometimes ago that rust is a homogenous mixture of Fe two and Three oxides. I will assume then this is not so.
I am not sure I understand this though: FeO-Fe2O3 is black, while Fe2O3 is red. By red I assume you also mean Orange rust?
‘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)
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Vargouille
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It is true that "rust" isn't exactly Fe2O3. It tends to be hydrated, and tends to have a composition somewhat different. That accounts for color
variations from orange to red. By removing the hydration from any red or orange rust you should get to something very close to Fe2O3, though.
FeO is, like FeO-F2O3, black in color, and it has the interesting attribute of decomposing to iron and FeO-F2O3 over time. It would be interesting if
you could manage to find the source of the tid-bit that iron is a mixture of ferrous and ferric oxides.
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ScienceSquirrel
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I suspect that orange to red rust approximate to hydrates of iron III oxide although there could be anions like carbonate, acetate, sulphate etc
present as well.
I have seen flakes of black rust, this is red to orange on one side and black on the other where it has flaked off the metal. I suspect that this
contains some iron II and some iron III, mainly as the hydrated oxides on the black side and mainly iron III on the red side.
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CHRIS25
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Ok, I went looking for it by typing in the same words that I remeber reading, unfortunately did not find it, but have a feeling that it is buried in a
document somewhere that I converted to PDF from the web about oxidation sates of of Iron.
However I did find this and it confirms what sciencesquirrel said above "I think"? http://umanitoba.ca/outreach/crystal/resources%20for%20teach... It is my experience that web addresses like these sometimes fail so I have copied
part of the document here if you want the full doc I will send it to you as a PDF if you like, it is only two pages or so:
The Squares here are Arrow Signs:
At one spot on the nail (the anodic site of our electrochemical cell) iron loses electrons (is oxidized) to form iron (II) ions.
Fe (s) Fe2+ (aq) + 2e-
At another spot on the nail the oxygen in the air combines with water and forms hydroxide ions.
½O2 (g) + H2O (l) + 2e- 2OH- (aq)
In the presence of oxygen the iron further oxidizes at the anode (loses electrons) to become iron (III) ions.
Fe 2+ (aq) Fe3+ (aq) + e-
The iron (III) ions and the hydroxide combine to form rust.
2Fe 3+ (aq) + 6OH- (aq) Fe2O3 (s) + 3 H2O (l)
Notice that water is required for the reaction at the cathode but produced in the overall reaction. It therefore is acting like a homogeneous
catalyst, to speed up the rusting of iron. In essence the water and oxygen make it easier for iron to rust.
I now have very very light green crystals precipitating out of solution of the ferrous chloride, which still has some steel wool inside. Are these
ferrous chloride crystals? The more I read about this topic the more confused I am becoming about what is what. There are two topics on this forum
from years ago which I am still reading, but the more I read the less clear it becomes. From what I can gather these ferrous chloride crystals will
oxidize, become ferric chloride and then absorb water very quickly and re-dissolve.
[Edited on 19-1-2013 by CHRIS25]
‘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)
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CHRIS25
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Hallo, I am having so much trouble working out how best to make this ferric oxalate. I can not buy it anywhere here, my very good supplier can not
source it in Ireland. So I am forced to make it. I have made a fairly concentrated solution of Ferric Chloride, though have no way of determining
how concentrated due to my inexperience with the often read complex way of titrating. Using NaOH or NH4 will only succeed inn telling me if there is
an absence of ferrous ions, and a normal titration with NaOH will interfere and give false results about how much free HCl there is in solution. So
i considered evaporating, getting the hexahydrate which would enable me to then perform a stoichemetry sound reaction. But the problem here seems to
be that I need to add water of course, this, as I have read, can be awkward in that the ferric chloride hydrolyses and will perhaps lead me into
adding to much Oxalic acid into the solution. I also need an oxalic acid free oxalate near enough, and this makes it all difficult to know how to
measure out the correct amounts of oxalic acid to the ferric chloride, again, any excess HCl in the solution is also going to throw the calculations
off. I do not wish to go down the road of using ferric ammonium sulphate and Ammonia solution since this seems more complex;and I do not have that
chemical anyway, I have loads of Iron, HCl and Oxalic acid hence this route seemed easier, at least it did a few weeks ago.
I would appreciate some insight into how I can begin to understand what to do please. If I could make this then this will be the last of the
chemicals that I have made in order to start a photography project with Kallitypes.
‘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)
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Vargouille
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I would evaporate to the hexahydrate, dissolve in dilute hydrochloric acid to prevent hydrolysis of the ferric ion, and mix with a solution of an
amount of oxalic acid in slight excess of stoichiometry. Filter the precipitate, wash with cold water to remove oxalic acid and hydrochloric acid, and
leave to dry. Should work like a charm.
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CHRIS25
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| Quote: Originally posted by Vargouille | | I would evaporate to the hexahydrate, dissolve in dilute hydrochloric acid to prevent hydrolysis of the ferric ion, and mix with a solution of an
amount of oxalic acid in slight excess of stoichiometry. Filter the precipitate, wash with cold water to remove oxalic acid and hydrochloric acid, and
leave to dry. Should work like a charm. |
Wow, so straightforward, very very grateful for your help here. Thankyou, I appreciate this.
‘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)
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