Oxidation state diagrams

Figure 12.16 Oxidation state diagram for phosphorus. (Note that all the oxoacids have a phosphorus covalency of 5.)...

Figure 13.16 Oxidation state diagram for As, Sb and Bi in acid and alkaline solutions, together with selected data on N and P for comparison.

Disproportionation of X2 in hot alkaline solution has long been used to synthesize chlorates and bromates (see oxidation state diagrams, p. 855) ... 

Figure 5. An oxidation state diagram for Mo, Cr, Fe and Mn. For Mo and Cr, N = III for Fe and Mn, N = II. Potentials are given at standard states in acid solution relative to the hydrogen electrode. On such a diagram, die slope between any two points equals the redox potential. In conh ast to most other metals, multiple Mo oxidation states are accessible over a small range of potentials. Note also that Mo is oxidized to Mo(VI) at relatively low potential (similar to Fe(III). Figure modified after Frausto da Silva and Williams (2001).

Fig. 2.9. Construction of an oxidation state diagram. The zero oxidation state has a volt-equivalent of zero (arbitrary). The slopes of the lines have values corresponding to...

Fig. 2.10. Oxidation state diagrams for (a) proportionation—C is below straight line linking A and B (b) disproportionation—C is above the straight...

Fig. 2.11. The oxidation state diagram for oxygen (from Ref. 8 with permissio...

Fig. 2. Oxidation state diagram of oxygen at pH 7 at otherwise standard conditions (lmolal concentrations, 1 atm for gases). The x-axis gives the oxidation state, the y-axis the product of reduction potential and oxidation state. As such the slope represents the reduction potential. Adapted from ref. [4]. A compound that lies above a line joining its neighbours is unstable with respect to disproportionation, as is the case for superoxide and hydrogen peroxide. The line from hydrogen peroxide to the middle of the water-hydroxyl line represents the one-electron reduction potential of the couple H202/ 0H, H2O.

The oxidation state diagrams in Figure 1 give a perspective on the relative stability of manga-nese(II) for OH2, OH and O2 ligands. 

In order to avoid this difficulty and give a more graphical description of a given system, Frost devised a free energy vs oxidation state diagram as shown below. From eq. 2.58 one has ... 

Friedel, A. Murray, R. Using Oxidation State Diagrams to Teach Thermodynamics and Inorganic Chemistry, /. Chem. Educ. 1977, 54, 485+87. 

Fig. 2. Oxidation state diagram 285) for copper. (Data from Ref. 207.)...

Equation (3) can be used to calculate the standard electrode potentials. Calculations based on the Bom-Haber cycle to obtain the relative stabilities of oxidation states are known as Oxidation State Diagrams . These diagrams have been found useful in clarifying inorganic chemistry (69), even though their accuracy is sometimes low. 

In a Frost or oxidation state diagram (see Fig. 2) each oxidation state (n) is assigned a volt... 

The oxoacids of P are clearly very different structurally from those of N (p. 459) and this difference is accentuated when the standard reduction potentials (p. 434) and oxidation-state diagrams (p. 437) for the two sets of compounds are compared. Some reduction potentials (E°fV in acid solution are in Table 12.8 - (p. 513) and these are shown schematically below, together with the corresponding data for alkaline solutions. 

The alternative presentation as an oxidation State diagram is in Fig. 12.16 which shows the dramatic difference to N (p. 438). 

Useful and illustrative thermodynamic data in the form of an oxidation state diagram and reduction potential vs. pH diagram have been reported by Koppenol [22]. 

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