Reaction between copper sulfate and ferric chloride

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...

Quote: Originally posted by AJKOER

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

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]

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]