Oxidation-reduction in solution

This results in the formation of a solution of iron(II) sulfate and leaves little pieces of copper metal in the bottom of the bucket. A hole is eventually eaten through the side or bottom of the bucket as the iron goes into solution. 

The kind of reaction just described is used in a process called cementation to purify some industrial wastewaters that contain dissolved metal ions. The water is allowed to fiow over iron scraps, and so-called heavy metal ions, such as 

Cementation results in the replacement of poisonous heavy metal ions in solution by relatively harmless iron. 

The electrons required for the reduction of Cu + are picked up from the bar of copper. On the right side, Fe is oxidized by the oxidation half-reaction 

Recall that this is the same reaction that occurs when CUSO4 solution contacts iron in a steel bucket (when that reaction was written, 804 was shown as a spectator ion—one that does not take part in the reaction). 

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B. G. Levich, Present state of the theory of oxidation-reduction in solution (bulk and electrode reactions), in Advances in Electrochemistry and Electrochemical Engineering. Vol. 4, P. Delahay, editor, Wiley-Interscience, New York, 1966, pp. 249-372. 

Levich V.G. (1965), Present state of the theory of oxidation-reduction in solution (btrlk and electrode reactiorts) , inDelahay P. and Tobias C. W., eds.,Adv. Electrochem. Electrochem. Eng. 4,249-371. 

One aspect that reflects the electronic configuration of fullerenes relates to the electrochemically induced reduction and oxidation processes in solution. In good agreement with the tlireefold degenerate LUMO, the redox chemistry of [60]fullerene, investigated primarily with cyclic voltammetry and Osteryoung square wave voltammetry, unravels six reversible, one-electron reduction steps with potentials that are equally separated from each other. The separation between any two successive reduction steps is -450 50 mV. The low reduction potential (only -0.44 V versus SCE) of the process, that corresponds to the generation of the rt-radical anion 131,109,110,111 and 1121, deserves special attention. 

Heteropolyacids (HPA) are the unique class of inorganic complexes. They are widely used in different areas of science in biochemistry for the precipitation of albumens and alkaloids, in medicine as anticarcinogenic agents, in industry as catalysts. HPA are well known analytical reagents for determination of phosphoms, silica and arsenic, nitrogen-containing organic compounds, oxidants and reductants in solution etc. 

The underlying theory may be simplified as follows. Polarography is concerned with electrode reactions at the indicator or micro-electrode, i.e. with reactions involving a transfer of electrons between the electrode and the components of the solution. These components are called oxidants when they can accept electrons, and reductants when they can lose electrons. The electrode is a cathode when a reduction can take place at its surface, and an anode when oxidation occurs at its surface. During the reduction of an oxidant at the cathode, electrons leave the electrode with the formation of an equivalent amount of the reductant in solution ... 

S.R. Smith and H.H. Thorp, Application of the electrocatalytic reduction of nitric oxide mediated by ferrioxamine B to the determination of nitric oxide concentrations in solution. Inorg. Chim. Acta 273, 316-319(1998). 

Among the nonnoble metals that can be synthesized by radiation-induced reduction in solution, nickel raises some difficulties because the atom formation and aggregation processes undergo the competition of oxidation reactions of highly reactive transients, such as monovalent Ni ion, Ni atom, and the very first nickel oligomers. Nevertheless, in... 

Again it seems not necessary to discuss the considerations of the chemical versus electrochemical reaction mechanism. It is clear from the extremely negative standard potential of silicon, from Eqs. (2) and (6), that the Si electrode is in all aqueous solutions a dual redox system, characterized by its OCP, which is the resultant of an anodic Si dissolution current and a simultaneous reduction of oxidizing species in solution. The oxidation of silicon gives four electrons that are consumed in the reduction reaction. Experimental results show clearly that the steady value of the OCP is narrowly dependent on the redox potential of the solution components. In solutions containing only HF, alternatively alkaline species, the oxidizing component is simply the proton H+ or the H2O molecule respectively. 

I wish to point out that these reactions were studied in either neutral or acidic solutions where the cyanide cobalt system is really unstable thermodynamically. I raise the question about oxidation-reduction in the iodo complex. This wasn t mentioned in the paper. It seems to me it would provide an alternate path which might increase the reaction rates in the case of the iodide complex. 

In this reaction, oxalate ion may be oxidized intramolecularly by cobalt(III) ion, but it is interesting to compare the three different systems in w hich there are three, two, or one oxalate ions with the cobalt(III) cation. The last one can be boiled in l.OM add for an hour and nothing happens. In the first one, decomposition will occur very readily in aqueous solution at 50°C., so that oxalate exchange can t be measured, for instance. The middle one has not been studied in any detail yet, as far as I know, but there is oxidation-reduction in this too, though much slower than in the first. I wonder if this inhibiting effect of the nonreacting ligand, the diamine, on the oxidation has any simple explanation. 

Joseph J. Jordan Prof. Duke said that one of his motivations for exploring oxidation-reduction in molten salts was his desire to study separately the electron transfer process proper, which in aqueous solutions is invariably complicated and encumbered by overlapping proton transfer. 

An electron is excited from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) when a molecule in solution absorbs light. The excited electron in the LUMO may transfer to a neighboring molecule (oxidant) in solution, leading to the reduction of the oxidant, whereas the electronic hole (electron vacancy) in the HOMO may transfer to another neighboring molecule (reductant) in solution, resulting in the oxidation of the reductant. Quite similar photoinduced reduction-oxidation processes can occur at the semiconductor/solution (semiconductor/liquid) interface when a semiconductor in solution absorbs light. Fig. 4.1 schematically illustrates the... 

If (23) is selected as the dihalosilane, a convenient way of modifying the nickel surface is available.64 The electrochemical properties of the treated nickel electrode are very similar to those of a similarly derivatized platinum electrode for example, both are equally effective in the elec-trocatalytic oxidation-reduction of solution ferrocene. Normally oxidation of the nickel surface would be a competing process ultimately rendering the electrode passive. The surface modification clearly eliminates this problem and opens up the possibility of using surface modified inexpensive metals as electrodes. 

The derivatives in the lower oxidation states Nb(II), Nb(HI), Ta(III) (known mainly for niobium) were obtained by the reduction of M(OR)5 by sodium amalgam [404, 1187], and bimetallic methoxoniobates (IV) by reduction with hydrogen in statu nascendi (Mg + MeOH) or on cathodic reduction in solution (method 7). The alkoxide chlorides ofNb(HI) and Nb(IV) crystallize on alcoholysis ofthe corresponding chlorides at low temperatures (method4) [416, 1731],... 

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