Stable equilibrium, conditions relation between

The relation between the potential-composition data for these two systems under equilibrium conditions is shown in Fig. 13. It is seen that the phase Li2hSn (Lil3Sn5) is stable over a potential range that includes the upper two-phase reconstitution reaction plateau in the lithium-silicon system. Therefore, lithium can react with Si to form the phase Li, 7 S i... 

Related compounds, cyclo[2.2.3]azine and l,2,3,4-dibenzocyclo[2.2.3]azine, also give ion radicals with peripheral 77-clcctron conjugate systems (Gerson et al. 1973 Mat-sumoto et al. 1996). The difference in conjugation between neutral molecules and their ion radicals can be additionally traced in the case of keto-enol tautomerizm. As a rule, enols are usually less stable than ketones. Under equilibrium conditions, enols exist only at very low concentration. However, the situation is different in the corresponding cation radicals, where gas-phase experiments have shown that enol cation radicals are usually more stable than their keto tautomers. This is due to the fact that enol cation radicals profit from allylic resonance stabilization that is not available to ketones (see Bednarek et al. 2001 and references therein) see Scheme 3-58 ... 

Reversible processes are those processes that take place under conditions of equilibrium that is, the forces operating within the system are balanced. Therefore, the thermodynamics associated with reversible processes are closely related to equilibrium conditions. In this chapter we investigate those conditions that must be satisfied when a system is in equilibrium. In particular, we are interested in the relations that must exist between the various thermodynamic functions for both phase and chemical equilibrium. We are also interested in the conditions that must be satisfied when a system is stable. 

The time of relaxation in this case constitutes 16 s, and therefore the equilibrium between NO, N02, and 03 in the atmosphere can be considered stable. However, the equilibrium N2 + 02v 2N0 under anthropogenic conditions relates to NO transforming into N02 over several hours. Therefore, from the viewpoint of global modeling, the separate consideration of the components NO and N02 is unnecessary here as well. In other words, we shall consider atmospheric nitrogen as a generalized component of the global model. 

Uranium Sulphate, U(S0j)3.nH20.—The anhydrous uranous sulphate has not been prepared, but an extraordinarily large number of hydrates is known. Salts containing 1, 2, 3, 4, 5, 6, 7, 8, and 9 molecules of w-ater have been described, and of these the di-, tetra-, octa-, and nona-hydrates are stable. The actual relation of these hydrates to one another is difficult to determine, as they undergo hydrolysis to a considerable extent when in solution, and the tetra-and octa-hydrates, at least, show a marked tendency to remain in a metastable condition at temperatures far removed from the transition-point between the two phases. Solubility determinations indicate that this transition-point is in the neighbourhood of 20° C., but it has been shown that the octahydrate wffien heated in absence of air changes into the tetrahydrate at 68° to 87° C. w hen the former hydrate is in a state of metastable equilibrium. 

Chemical equilibrium appears to be the most helpful model concept initially to facilitate identification of key variables relevant in determining water-mineral relations and water-atmosphere relations, thereby establishing the chemical boundaries of aquatic environments. Molar Gibbs free energies (chemical potentials) describe the thermodynamically stable state and characterize the direction and extent of processes approaching equilibrium. Discrepancies between predicted equilibrium composition and the data for the actual system provide valuable insight into those cases in which important chemical reactions have not been identified, in which non-equilibrium conditions prevail, or where analytical data for the system are not sufficiently accurate or specific. Such discrepancies are incentive for research and the improvement of existing models. 

Apparently, the microwave conditions are suitable to drive the equilibrium between the two diastereomers toward the thermodynamically more stable syn-syn isomer, which was confirmed in a separate control experiment [382]. Similar results were obtained by Holzgrabe and coworkers for related systems using chloroform as solvent under microwave conditions [383]. 

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