Reduction equilibrium

RL Cutler, AM Davies, S Creighton, A Warshel, GR Moore, M Smith, AG Mauk. Role of arginine-38 in regulation of the cytochrome c oxidation-reduction equilibrium. Biochemistry 28 3188-3197, 1989. 

It can react only when E -E > 0. In other words, sulphide minerals are corrupted only when the reduction equilibrium potential for an oxidant is higher than the oxidation equilibrium potential in sulphide mineral solution. Generally speaking, the oxidant is oxygen. Oxygen is the essential condition for the electrochemistry flotation of sulphide mineral. 

When the methyl viologen reached its reductive equilibrium, noted by the start of hydrogen evolution, the enzyme in the side arm was tipped into the main compartment, and the reaction stopped after 10 min. The solution in the main compartment of the flasks were analyzed for ferrous ion concentration, which is a measurement for metal corrosion. 

Sturgis MB. 1936. Changes in the oxidation-reduction equilibrium in soils as related to the physical properties of the soil and the growth of rice. Louisiana Bulletin No 271. Baton Rouge, LA Ix)uisiana State University and A M College. 

Evaluation of the contribution made by the proximal ligand to the oxidation-reduction equilibrium of Mb (H93 in the wild-type protein (Fig. 2)) has been more difficult because substitution of the proximal residue results in expression of apo-Mb without heme incorporation. All of the available data for these variants (Table I), therefore, derive from proteins prepared by reconstitution of purified recombinant apoprotein with exogenous heme 69, 70, 72). In those cases where trace quantities of native Mb are produced (73), heme extraction followed by reconstitution was undertaken to eliminate complications from suIfMb... 

One mechanism postulates a rapid preliminary equilibrium between the reactants which, in effect, would be a mutual oxidation-reduction equilibrium... 

TT heoretical equilibrium models can be established for oxidation-reduc-- tion systems in natural waters in much the same way that acid-base or solubility models have been developed and found useful in interpreting observed concentrations of ions and other materials. To relate the theoretical models for redox processes to observed conditions and processes in the aquatic environment is, however, much more difficult and cannot be done as rigorously. Primarily this situation occurs because true oxidation-reduction equilibrium is not observed in any natural aquatic system this is partly because of the extreme slowness of most oxidation-... 

The application of the law of mass action is straightforward. For example in the case of the oxidation-reduction equilibrium 2Fe3+ +Sn2+ 2Fe2+ +Sn +... 

The tritium label (at the C-14 position) was found to be only about 50% retained, and in fact the actual amount varied from one feeding experiment to the next (130). An oxidation-reduction equilibrium... 

Oxidation/reduction equilibrium redox Mn04 + 5Fe2+ + 8H+ Mn- -f- 5Fe- + -f dHjO V redox... 

With iron it appears certain that the pure reduced metal is not the phase of highest activity when the metal is exposed to synthesis gas at reaction temperatures, the activity slowly increases, indicating that the active phase is still being formed. Indeed, Pichler (5) reported that a pseudohexagonal carbide FcjC is the active phase. Besides carbide formation the oxidation of the catalyst surface is of importance. As Eqs. (1)—(3) show, hydrogen is consumed and H2O formed. With respect to the oxidation-reduction equilibrium of the catalyst metal M,... 

Reid LS, Taniguchi VT, Gray HB, Mauk AG (1982) Oxidation reduction equilibrium of cytochrome-B5. J Am Chem Soc 104 7516—7519... 

Oxidation-reduction equilibrium also implies that the electrode potentials of all redox couples in the system are equal. Because of irreversibili ty, this condition is rare in mixtures of redox couples, especially in mixtures containing organic and nitrogen compounds such as the soil solution. 

The reduction equilibrium of nickel(Il) chloride was studied by a flow method. The results were probably flawed by vaporisation of NiCb, thus they were not subjected to a third law analysis. The experimental data depicted in Figure V-16 are listed in... 

Many chemical reactions in wine are characterized by electron transfers, leading to the oxidation and reduction phenomena. These reactions occur simultaneously and continue until an oxidation-reduction equilibrium is reached. The oxidation-reduction potential of a wine is an observation of the oxidation and reduction levels of the medium at a certain equilibrium. This value is quite comparable to pH as a measurement of a wine s acidity. Its value is linked to the quantity of dissolved oxygen, just as pH depends on the quantity of (H+) protons. Furthermore, it is possible to define the normal potential Eq of a given oxidiz-ing/reducing couple when half the component is oxidized and half is reduced. This characterizes the wine s oxidation capacity in the same way as p indicates the strength of an acid. 

The oxidation-reduction equilibrium in soils is usually expressed in terms of Eh, but just as pH that measures proton activity on the basis of moles per liter. Eh can be expressed as pe (negative logarithm of the electron activity). 

Several other methods for controlled radical polymerization have been developed and should be applicable to elastomer synthesis (Matyjaszewski, 1998, 2000). One of the other most important systems for controlled radical polymerization is atom transfer radical polymerization (ATRP) (Matyjaszewski and Xia, 2001). A transition metal (Mt) catalyst participates in an oxidation-reduction equilibrium by reversibly transferring an atom, often a halogen, from a dormant species (initiator or polymer chain) as shown below. 

Funk WD, Lo TP, Mauk MR, Brayer GD, MacGil-livray RT, Mauk AG (1990) Mutagenic, electrochemical, and crystallographic investigation of the cytochrome b5 oxidation-reduction equilibrium involvement of asparagine-57, serine-64, and heme propionate-7. Biochemistry 29 5500-5508... 

The equilibrium conditions for each reaction may be expressed in terms of the partial pressure ratios of CO to CO2 and are illustrated in Eigure 5.1. As a simplification this assumes solid-gas reactions with unit activity of the solid oxide reactants. If in the molten phase, such as PbO dissolved in slag, the activity will be much lower and the eqnihbrinm ratios for COiCOj will be correspondingly higher. For partial pressure ratios of one or above, covering the bulk of the reactions zones of the shaft. Figure 5.1 indicates that PbO reduction should proceed readily, ZnO can be reduced to zinc vapour above 800°C, and iron oxides will be reduced primarily to FeO. In Figure 5.1 the ZnO reduction equilibrium is shown for a zinc vapour partial pressure of 0.01 atmospheres or one per cent in the gas stream. Zinc partial pressure will vary widely however, this serves only to illustrate that zinc vapour will be present at partial pressures of this order. 

As the number of gas molecules does not change before and after reduction, so the pressure does not affect the movement of reduction equilibrium. However, because the reduction process is not in equilibrium, the effect of pressure on the oxide reduction process is very complicated, which is related to reduction conditions and reductant. If hydrogen is used as a reductant, then, to a large extent, the effect of pressure on the reduction process is related with the relevance of which stage are the controlling steps. 

In a typical ATRP, the dormant chain is terminated as an alkyl halide. The dormant chain interacts with a transition metal in an oxidation/reduction equilibrium (one electron oxidation of the transition metal) to generate the polymer radical which can react with monomer and propagate. The propagating radical reacts with the oxidized transition metal to form a new dormant chain terminated as an alkyl halide. Because the propagating radical exists mainly in the dormant state, there is a relatively low concentration of the active radical and therefore fewer opportunities for termination due to chain coupling or disproportionation. 

Calculating the value 1.73 V from the value 1.51 V is achieved according to the principles given in Chap. 2, that is, through the calculation of free enthalpies. It is sufficient to note that the reduction equilibrium of the hypochlorite ion is the sum of the reduction equilibrium of hypochlorous acid and the protonation equilibrium of the hypochlorite ion ... 

The standard potential of the couple corresponds to the half-reduction equilibrium... 

In this section are grouped a variety of what are termed chemical properties of fused salts which do not properly fit into earlier sections. These are subdivided into oxidation-reduction equilibrium and kinetic studies in melts and some of the promising prospects for synthesis using fused salts. 

In some cases examined, diacylated compounds were isolated in yields up to 23% and a thermal oxidation-reduction equilibrium between the monoacylated product and the initial quinone, followed by a rapid, secondary acylation of the intermediary generated acylated quinone was suggested to explain their formation. Secondary acylation was indeed demonstrated with acetyl-1,4-benzoquinone (54), and acetaldehyde and the corresponding diacylated products 58 and 59 were isolated in 20% total yield (Scheme 16). ... 

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