Oxygen species, thermodynamic data

Manes and Manes-Pozzi have suggested a cluster of the type (Vq 2 Me ), which has been taken as the basis species for a statistical treatment aimed at the interpretation of the thermodynamic data on (Ui yPUy)02 x and Pu02 x. This cluster has later been called by Manes, Sdrensen et al. the tetrahedral defect The reason of this name lies in the fact that the local bond is supposed to occur in a coordination tetrahedron of an oxygen ion in the fluorite structure in this tetrahedron, one oxygen vacancy is formed, and the two electrons are shared with the four surrounding cations, giving rise (formally) to 2(Me ) locally bonded with the vacancy. Manes, Sorensen et al. showed that by... 

Good thermochemical values for halogenated compounds have lagged behind those for hydrocarbons. Until recent years only the crudest estimates were available, even for some of the most common compounds. Now, however, reliable thermodynamic data have become available for some species, though there is still uncertainty for many other species, especially those containing oxygen. 

B is less volatile than Si, however, B may react with oxygen and hydrogen at elevated temperatures to form the volatile species BHO, BO, and BH2. To increase the temperature at the bath surface, plasma heating has been employed in laboratory experiments. The reacting species calculated from thermodynamic data are given by Alemany et al. [11] and shown in Fig. 1.8. One problem is that Si will also be oxidized by the water vapor, giving some loss of Si, both as SiO and Si02. 

Tables 1.11 to 1.13 give the thermodynamic data of elements in the standard state and of hydrocarbon and oxygenated, molecular and radical species, containing at most 2 carbon atoms.

R2O2, R = rare-earth metal, have been observed as minor species in the rare-earth-oxygen systems at high temperatures (Smoes et al. 1965, Piacente et al. 1973, Pupp and Gingerich 1971, Staley and Norman 1969, Kordis and Gingerich 1977). They are about a factor of hundred to a thousand times less abundant than either the monoxide or the metal atom species. As such the thermodynamic data for these polyatomic oxides are very limited. The most extensive study of these polyatomic oxides was by Kordis and Gingerich (1977). The data presented here are taken primarily from this source and are recalculated using more recent data for the reference molecules presented in table 1. 

Electrochemistry of the Al-Oj couple. Figure D.5 shows a general schematic of a typical Al-air system. Tables D.4 and D.5, respectively, contain thermodynamic data for pure species and soluble species involved in the equilibria associated with aluminum, water, and oxygen. Table D.6 contains the chemical and electrochemical reactions possibly occurring in a typical Al-air corrosion cell. 

The oxygen dissociation pressure at temperatures below those where metal containing species are significant have yielded thermodynamic data on the intermediate oxides of praseodymium and terbium as discussed in section 2.3. 

Electrochemical experiments and surface analyses show that the adsorbed oxygen species in solution on most transition metals at 25°C are likely to be hydroxyls. Thermod5mamic data obtained from electrochemical experiments are available only for on copper [49]. Therefore Oads is considered here on Fe, Ni, and Cr and on Cu. The standard Gibbs energies of formation (chemical potentials) for sulfur and oxygen adsorbed on metal surfaces can be calculated [44-46] from literature thermodynamic data for reversible chemisorption at the metal-gas interface. 

Owing to the allotropic forms of oxygen, to its various redox states, and related chemical species that are thermodynamically stable or exist for kinetic reasons, a lot of redox reactions are usually described. However, many of them are not really important for the common works, particularly for those in solutions consequently, only some of them have been described here. The publications cited earlier can be searched for data useful for the calculation of Gibbs energy or potentials of particular reactions. 

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