Oxidation potential calculation

CuCi(s) + AgCi(s) - CuCi2(aq) + Ag(s) reads K - 1.86xl0-8. Using appropriate standard oxidation potentials, calculate the standard oxidation potentials for the Cu, CuCi(s) Ci" half cell. 

Fig. 5 Oxidation potentials calculated at the HF/6-31 + G (d, p) level for three solvation models isodensity polarizable continuum model (IPCM), polarizable continuum model (PCM), and solvation model based on density (SMD). Experimental oxidation potentials (EXP) are from the literature. Reproduced with permission [91]. Copyright 2011 American Chemical Society...

Thus electrode potentials may be calculated from oxidation potentials, and vice versa. 

A knowledge of the concentrations of all reactants and products is necessary for a description of the equilibrium state. However, calculation of the concentrations can be a complex task because many compounds may be Imked by chemical reactions. Changes in a variable such as pH or oxidation potential or light intensity can cause large shifts in the concentrations of these linked species. Aggregate variables may provide a means of simplifying the description of these complex systems. Here we look at two cases that involve acid-base reactions. 

Ce(IV) + Fe(II) system, as calculated by Dulz and Sutin, on the grounds that the rate of the Fe(III)+Fe(II) exchange (/ci,i) and the corresponding oxidation potential relate to HCIO4 media, whereas the rate (A 2,2) and oxidation potentia of the Ce(IV)+Ce(III) system are for H2SO4 media. Adamson et arrive at a calculated value of 1.3 x 10 l.mole sec for the rate coefficient (A i,2) of the Ce(lV)+Fe(II) reaction in 0.5 M HCIO4 at 0 °C. Since this value is very much at variance with the observed value (700 l.mole sec" ), they conclude that this oxidation takes place by an atom-transfer mechanism, to which the theoretical treatment of Marcus is not appropriate. 

Related Polymer Systems and Synthetic Methods. Figure 12A shows a hypothetical synthesis of poly (p-phenylene methide) (PPM) from polybenzyl by redox-induced elimination. In principle, it should be possible to accomplish this experimentally under similar chemical and electrochemical redox conditions as those used here for the related polythiophenes. The electronic properties of PPM have recently been theoretically calculated by Boudreaux et al (16), including bandgap (1.17 eV) bandwidth (0.44 eV) ionization potential (4.2 eV) electron affinity (3.03 eV) oxidation potential (-0.20 vs SCE) reduction potential (-1.37 eV vs SCE). PPM has recently been synthesized and doped to a semiconductor (24). 

The interatomic distances for such an intermediate were calculated,288 and, using the resulting data in conjunction with certain steric and oxidizing-potential considerations, it was successfully predicted that sodium bis-muthate and trivalent silver ion would also specifically oxidize 1,2-glycols. These reactions have since been studied.287 288... 

Bors et al. [175] determined the rate constants and equilibrium constants for the reactions of flavonoids with ascorbate (Reaction (18)) by a pulse-radiolysis method and on their basis calculated the one-electron oxidation potentials of flavonoids (Table 29.9). 

The results of MO calculations are consistent with the oxidation potentials of silyl-substituted ethers in which the rotation around the C -O bond is... 

Boberski and Allred reported that oxidation potentials of permethylpoly-silanes determined by a.c. polarography decrease with increasing chain length, and that the oxidation potentials are correlated almost linearly with the energies of the HOMO as determined by MO calculations (Table 7) [63]. 

To summarize, the standard cell potential can also be calculated as the sum of a standard reduction potential and a standard oxidation potential. 

A standard cell potential depends only on the identities of the reactants and products in their standard states. As you will see in the next Sample Problem, you do not need to consider the amounts of reactants or products present, or the reaction stoichiometry, when calculating a standard cell potential. Since you have just completed a similar Sample Problem, only a brief solution using the subtraction method is given here. Check that you can solve this problem by adding a reduction potential and an oxidation potential. 

In this section, you learned that you can calculate cell potentials by using tables of half-cell potentials. The half-cell potential for a reduction half-reaction is called a reduction potential. The half-cell potential for an oxidation half-reaction is called an oxidation potential. Standard half-cell potentials are written as reduction potentials. The values of standard reduction potentials for half-reactions are relative to the reduction potential of the standard hydrogen electrode. You used standard reduction potentials to calculate standard cell potentials for galvanic cells. You learned two methods of calculating standard cell potentials. One method is to subtract the standard reduction potential of the anode from the standard reduction potential of the cathode. The other method is to add the standard reduction potential of the cathode and the standard oxidation potential of the anode. In the next section, you will learn about a different type of cell, called an electrolytic cell. 

Bordwell (Bordwell and Bausch, 1986) has developed a method to determine C—H BDEs from a combination of p ha values and oxidation potentials (E ) of the corresponding anions in dimethyl sulphoxide solution. These acidity-oxidation potentials (AOP) are taken as measures for BDEs and are related to the stabilization of the radicals formed. This procedure has been recently applied to the subject of captodative stabilization (Bord-well and Lynch, 1989). Values of ABZ) relative to the C—H BDE in methane are calculated according to (13). These values are set equal to the... 

The potential calculated using above reaction is -0.27 V at pH= 11 at dissolved species 10 " mol/L corresponding to the potential of the cathodic current rise, further indicating the elemental sulphur as the oxidation product. 

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