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Author: Subject: Reaction between copper sulfate and ferric chloride
AndrejJoszika
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[*] posted on 2-3-2018 at 04:54
Reaction between copper sulfate and ferric chloride


I am new to the world of home-chemistry and I want to perform an experiment, but first I would like to know if the reaction takes place. Do copper sulfate and ferric chloride react? Is it 3CuSO4 + 2FeCl3 -> Fe2(SO4)3 + 3CuCl2, or do i get an ionic reaction? I searched this reaction on the internet, but I didn't find much.
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Boffis
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[*] posted on 2-3-2018 at 07:54


This question has been asked a hundred times before in some form or other. They are both highly disassociated in solution but the ions don't react. If the solution is evaporate the least soluble combination tends to crystallise first. So you get the same product whether you mix ferric chloride with copper sulphate or ferric sulphate and copper chloride.
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AJKOER
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[*] posted on 3-3-2018 at 17:09


Yes, Boffis, you have answered the question reputedly correctly.

However, in practice with say light and air exposure, I would not be too surprised if perhaps one gets a precipitate in time.

My thoughts, the light helps convert some ferric to ferrous. The presence of Fe(ll) with C(ll) enables a redox couple forming Cu(l) via the equilibrium reaction:

Fe(ll) + Cu(ll) = Fe(lll) + Cu(l)

At this point, either a precipitate of the insoluble cuprous forms, or it becomes a soluble complex. Assuming the latter case, as aqueous FeCl3 is acidic it supplies H+ and air provides oxygen. Then, either of following reaction could then proceed:

Cu(l) (aq) + O2 + 2 H+ --> Cu(OH)2 (s)

Fe(ll) (aq) + O2 + 2 H+ --> Fe(OH)3 (s)

which usually creates an insoluble basic salt (for example, a basic chloride). Note, with more light and oxygen, the process continues.

In my opinion, this transition metal brew has to be kept in the dark without any air exposure, or something may eventually be visible.

[Edited on 4-3-2018 by AJKOER]
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[*] posted on 3-3-2018 at 20:13


Quote: Originally posted by AJKOER  
However, in practice with say light and air exposure, I would not be too surprised if perhaps one gets a precipitate in time.

My thoughts, the light helps convert some ferric to ferrous. The presence of Fe(ll) with Cu(ll) enables a redox couple forming Cu(l) via the equilibrium reaction...

That's a highly imaginative prediction. If there is any formation of a precipitate over time, it would most likely due to slow evaporation of hydrogen chloride and formation of basic iron or copper chlorides. Fe(II) will not reduce Cu(II) to Cu(I).




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[*] posted on 4-3-2018 at 01:38


@Ajoker, your post is complete bollocks.

IF your solutions are dilute or neutral slow hydrolysis WILL deposit basic phases from Fe3+ and Cu2+ solutions but there is no redox reaction because there is nothing to donate electron under these aqueous conditions. These reactions are simple hydrolysis and because they generate H+ ions they are ultimately self limiting as the process reaches equilibrium.
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[*] posted on 4-3-2018 at 02:58


Quote: Originally posted by AJKOER  


My thoughts, the light helps convert some ferric to ferrous.


To exactly the same extent that sunshine destroys rust.

Why do you post tosh like that?
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AJKOER
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[*] posted on 4-3-2018 at 06:53


Some prior comments and sources:

Quote: Originally posted by AJKOER  
To quote Woelen, in part, from above:

"Conclusion:

Excess Fe(3+) ---> Not all copper (I) is oxidized to copper (II)
Excess Fe(2+) ---> Not all copper (II) is reduced to copper (I).

This seems a contradiction, so there must be a copper (A) species in solution with 1 < A < 2, in other words a fractional oxidation state of copper..."

From a recent thread, a link to an educational reference with a somewhat succinct comment as to a "coupled redox reaction" (see https://www.sciencemadness.org/whisper/post.php?action=reply... ):
Quote: Originally posted by AJKOER  
Per my Wikipedia reference on what I contend is a similar reaction scheme occurring with acetate, cited equations to quote:

" CuCl2 + Cu + 2 NaCl → 2 NaCuCl2 (eq.6)
6 NaCuCl2 + 3/2 O2 + H2O → 2 Cu2(OH)3Cl + 2 CuCl2 + 6 NaCl (eq.7) "

where Equation (7) indicates redox chemistry.

So, assuming we can move the cupric into cuprous, a redox reaction could proceed. In the above cited system, the presence of copper metal assisted in forming cuprous from cupric. Alternately, to quote a source ( https://www.researchgate.net/publication/11374766_Generation...):

"The process is enhanced by contaminating Fe3+ and Cu2+;"
"The addition of Fe2+ and Cu+ (0-20 microM) to KH resulted in a concentration-dependent increase in *OH formation, as measured by the salicylate method."

where an iron contamination could arise from using tap water (containing some ferrous bicarbonate, for example, and noting in the opening thread, to quote MrbunGee, "I was not using distilled water, but there just can’t be that much CO3 ions in my water. :?" ).

[Edit] Yet another reference:

Fe2+ + Cu2+ ↔ Fe3+ + Cu+ (coupled redox reaction)

See: https://www.google.com/url?sa=t&source=web&rct=j&...

[Edited on 23-9-2016 by AJKOER]


Note, the comment above "The process is enhanced by contaminating Fe3+ and Cu2+", which is repeated in the research literature, citing the apparent beneficial impact of a mixed transition metal system which can introduce a coupled equilibria. In the same 2000 paper "Generation of .OH initiated by interaction of Fe2+ and Cu+ with dioxygen; comparison with the Fenton chemistry" by Norbert K. Urbañski and Andrzej Berêsewicz, available at https://www.google.com/url?q=http://www.actabp.pl/pdf/4_2000... , the authors noted to quote "The Fe2+-mediated .OH yield was enhanced not only by Fe3+ but also by Cu2+ (Fig.3)".

Also, supporting material from more recent work on hetergeneous transition metal catalysts, "Review on the application of modified iron oxides as heterogeneous catalysts in Fenton reactions", by Shima Rahim Pouran, et al, 2011 available at http://www.researchgate.net/publication/257353836_Review_on_... , where the authors note in the case of transition metal substituted iron oxides (TMSIOs), to quote:

"Two mechanisms were suggested for enhanced activity of TMSIOs: (i) the participation of the thermodynamically favourable redox pairs, Fe3+/Fe2+ and Mn+/Mn+1, in H2O2 oxidation cycle, to produce OH radicals and (ii) generation of oxygen vacancies on the surface of catalyst, resulted from adjustments of unequal charge replacements".

In another work, "Impact of MnO2 on the efficiency of metallic iron for the removal of dissolved CrVI, CuII, MoVI, SbV, UVI and ZnII", by C. Noubactep K.B.D., et al. , 2011 (link: http://www.sciencedirect.com/science/article/pii/S1385894711... ), the authors confirms the observation that manganese oxide (MnO2) sustains the reactivity of metallic iron (Fe0) in a multi-elemental aqueous system containing Cr(VI), Cu(II), Mo(VI), Sb(V), U(VI), and Zn(II).

It is important to note that the coupled redox equilibrium can be dependent on the solubility of the lower valent state salt. So, for example, Cu(l) is more soluble in presence of chloride (complexation), which could explain the beneficial effect of say NaCl in a Fenton-type reaction occurring in a mixed transition metal system.

For additional references particular to coupled redox systems see, for example: https://www.google.com/url?sa=t&source=web&rct=j&... which restates the Fe/Cu system and for a more complex case example, see http://pubs.acs.org/doi/abs/10.1021/om960749b .

Per another source (link: http://chem.libretexts.org/Textbook_Maps/Inorganic_Chemistry_Textbook_Maps/Map%3A_Inorganic_Chemistry_(Wikibook)/Chapter_04%3A_Redox_Stability_and_Red ox_Reactions/4.4%3A_Redox_Reactions_with_Coupled_Equilibria ) to quote:

"Coupled equilibria (solubility, complexation, acid-base, and other reactions) change the value of E°, effectively by changing the concentrations of free metal ions."

where, for example, a pH change could arise from metal autoxidation via dioxgen as was noted above.

Twenty years ago the importance of coupled redox reactions was bearly addressed. This was unfortunate given its subsequent benefit it apparently provided in some adanced oxidation processes/technologies (where, for the most part, AOP/AOT focus is on drinking water purification and environmental remediation of polluted soil and waste water). As an example, a quote from the last page of a published 1996 article, "Catalytic Metals, Ascorbate and Free Radicals: Combinations to Avoid", by Garry R. Buettner and Beth Anne Jurkiewicz, (link: https://www.google.com/url?sa=t&source=web&rct=j&... ), to quote:

"One area that has only been examined briefly is the potential synergy of metals in oxidations. Our colleagues in environmental research have noted that iron and copper are co-conspirators in the oxidation of organics in atmospheric waters (79). It was determined that reduced copper transferred an electron to iron, which in turn participates in the oxidation process.

k= 3 x E07 M–1s–1 (79)

Cu1+ + Fe3+ → Cu2+ + Fe2+

These same processes may be of significance in a biological setting."
-----------------------------------------------------------------------
It is important to understand the mechanics of Fenton and Fenton-type reactions as they move lower state transition metals to higher valent states. As an example, see "Fenton chemistry in biology and medicine*" by Josef Prousek, to quote reaction (15) on page 2330:

"For Fe(II) and Cu(I), this situation can be generally depicted as follows [20,39],

Fe2+/Cu+ + HOX → Fe3+/Cu2+ + .OH + X- (15)

where X = Cl, ONO, and SCN. "

[Edited on 9-10-2016 by AJKOER]


Link: http://www.sciencemadness.org/talk/viewthread.php?tid=80874

Also:

Quote: Originally posted by AJKOER  
In the case of a ferrous/O2/H+ reaction system, metal autooxidation (see http://pubs.acs.org/doi/abs/10.1021/ja01600a004 ) is believed to be accelerated in the presence of cupric, likely found in sea water. The claimed redox couple equilibrium reaction, in which cuprous is created and promotes a redox reaction, is:

Fe(ll) + Cu(ll) = Fe(lll) + Cu(l)

The issue with the above is that cuprous is not usually soluble. However, in the presence of NaCl, a soluble salt can be formed:

NaCl (aq) + CuCl = Na[CuCl2] or NaCl-CuCl-H20 (a polynuclear complex, see http://iopscience.iop.org/article/10.1070/RC2000v069n11ABEH0... )

This is one step in a commercial preparation path to basic cupric chloride (see Equation 6 at https://en.wikipedia.org/wiki/Dicopper_chloride_trihydroxide ).

So NaCl (or KCl) could contribute to the solubility of cuprous, which supports the Fe/Cu redox couple equilibrium that promotes a Fe(ll)/O2 redox reaction.

[Edited on 1-11-2017 by AJKOER]


Link: http://www.sciencemadness.org/talk/viewthread.php?tid=77903

On the topic of photo-fenton, see equation (4) at: http://cdn.intechopen.com/pdfs/29377.pdf . Namely:

Fe(lll) (aq) + H2O + hv ---> Fe(ll) + .OH + H+

Now, unionised comment: "To exactly the same extent that sunshine destroys rust" has merit as there is a high variance with respect to the ability of iron species capable of promoting photo activity. Note, I would not rule out CO2 presence in the system, but still I only prefer this photo causation argument over the explanation "(ii) generation of oxygen vacancies on the surface of catalyst, resulted from adjustments of unequal charge replacements", noted above, as my knowledge of physical chemistry is weak. However, I did say a precipitate 'may' form in an unspecified time frame.

If there are still questions, I may be able to further add detail (however, I did originally wanted to avoid this extensive exposition).

[Edited on 4-3-2018 by AJKOER]
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[*] posted on 4-3-2018 at 09:36


It's true that (fairly high energy) uv can convert Fe(III) to Fe(II).

The reaction also generates reactive oxygen species in exactly the right quantities to convert the Fe(II) back to Fe(III) so there's no net production of Fe(II).

And if we assume there's air present...
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