Chemical potential of compound

As we have seen before, COSMO-RS is able to describe the chemical potentials of compounds in almost any pure or mixed liquid phase, as long as the chemical composition of the liquid is known and as long as it can be considered as a chemically homogeneous phase. While this has opened an enormously broad range of applications in chemical engineering, these limitations exclude COSMO-RS from a number of important application areas in environmental simulations, life-science modeling, and product development. 

The combinatorial contribution p comb to the chemical potential of compound i is... 

The discussed chemical transfomiations can be visualized in the coordi nates of current chemical potential values (see Figure 2.4a), where chemi cal potentials of components R, Pj, and P2 are the external parameters. While this is the case of the absence of common intermediates, an indirect influence of the second reaction on the first reaction is possible only when chemical potential iTp2 of compound P2 (its thermodynamic rush P2) is higher than the chemical potential of compound R (its thermodynamic rush R). When so, the consecutive reaction P2 — R Pi becomes pos sible, and this compound P2 can be involved as an additional substrate into the main reaction R — Pi. In the considered example, the phenomenon of conjugation of chemical processes is not observed. The conjuga tion takes place only in the presence of common intermediates for both channels of the transformations. 

The Gibbs free energies of formation, AG = p(po) T o), of compounds are tabulated. We shall consider the use of AG in more detail in Chapter 9 devoted to the thermodynamics of chemical reactions. From these values the chemical potentials of compounds can be calculated as explained above. We conclude this section by noting that substitution of (5.3.3) into (5.3.4) gives us a general... 

Because only differences in chemical potential can be measured, the chemical or electrochemical potential of each species is broken down as in equation 3. An arbitrary secondary reference state is defined for each compound. For instance, the chemical potential of chlorine gas is expressed as... 

The chemical potential diagram for this ternaty system (Figure 3.3) shows that the reaction with the elements would reduce the iodine pressure to a very low value, which is not suitable for CVD, whereas tire compound Ta5Si3, in which the chemical potentials of the two elements are about 40kJgram-atom would be suitable for CVD at about 1300 K. 

The chemical potential of one half-cell depends on the concentration ct of the compounds which react at the electrode ... 

As a result of Eq. (11) we are able to calculate the chemical potential of any molecule X in any liquid system S, relative to the chemical potential in a conductor, i.e. at the North Pole. Hence, COSMO-RS provides us with a vehicle that allows us to bring any molecule from its Uquid state island to the North Pole and from there to any other liquid state, e.g. to aqueous solution. Thus, given a liquid, or a reasonable estimate of AGjis of a soUd, COSMO-RS is able to predict the solubility of the compound in any solvent, not only in water. The accuracy of the predicted AG of transfer of molecules between different Uquid states is roughly 0.3 log units (RMSE) [19, 22] with the exception of amine systems, for which larger errors occur [16, 19]. Quantitative comparisons with other methods will be presented later in this article. 

Most commercial Fischer-Tropsch refinery designs (Figures 18.1 to 18.9) included the co-production of chemicals with transportation fuels. The chemicals potential of Fischer-Tropsch syncrude has been pointed out repeatedly.38,47,65 66 This is a natural consequence of the properties of Fischer-Tropsch syncrude, that is, richness in linear hydrocarbons, olefins (especially linear a-olefins), and oxygenates. Furthermore, it is sulfur-free and nitrogen-free, which enables access to synthetic routes sensitive to such compounds. 

Figure 1.1 (a) Chemical potential diagrams for systems forming a complete range of solid solutions. The tangent shows at its terminal points, X, Y the chemical potentials of the elements x and y which are in equilibrium with the solid solution of composition M (b) Potentials for the system A-B, which forms the two stable compounds the stoichiometric A2B and the non-stoichiometric AB2. The graph shows that there are many pairs of potentials A, B in equilibrium with A2B and only one pair for a particular composition of AB2 AB is metastable with respect to decomposition to A2B and AB2... 

The chemical potential of a solute in equilibrium with its solid or liquid phase is equal to the chemical potential of the neat compound. It is therefore hardly surprising that some papers claiming to report on on water chemistry merely report reactivity comparable to reactivity of the neat reactants. In the author s opinion, the term on water chemistry would preferably be reserved for those processes for which additional rate-enhancing effects are found. 

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