Thermodynamical considerations

Tolman [21] concluded from thermodynamic considerations that with sufficiently curved surfaces, the value of the surface tension itsc//should be affected. In reviewing the subject, Melrose [22] gives the equation... 

One can distinguish between a tliennodynamic and kinetic stability to corrosion. C2.8.2.1 THERMODYNAMIC CONSIDERATIONS... 

Reaction (5. EE) is particularly useful for the discussion of thermodynamic considerations because of the way differences in thermodynamic state variables are independent of path. Accordingly, if we know the value of AG for reaction (5. EE), we have characterized the following ... 

Thermochemistry. Thermodynamic considerations ate of utmost importance in fluorinations. Table 1 is based on JANAF data (25) for CH, which indicate an average carbon-hydrogen bond strength of 410.0 kj/mol (98 kcal/mol) based on the atomization energy of CH. ... 

Reaction with Metals. Thermodynamic considerations for the reaction... 

Thermodynamic data are available only for the lower alkylamines, mainly estimates based on a few experimental deterrninations (3,4). Many manufacturing processes appear to be limited by thermodynamic equiUbria. The lack of accurate free energy data for these amines limits the appHcation of thermodynamic considerations, in contrast to the situation in hydrocarbon technology. 

Thermodynamic considerations demand that the energy necessary for biosynthesis of any substance exceed the energy available from its catabolism. Otherwise, organisms could achieve the status of perpetual motion machines A few molecules of substrate whose catabolism yielded more ATP than required for its resynthesis would allow the cell to cycle this substance and harvest an endless supply of energy. 

An important part of the optimization process is the stabilization of the monomer-template assemblies by thermodynamic considerations (Fig. 6-11). The enthalpic and entropic contributions to the association will determine how the association will respond to changes in the polymerization temperature [18]. The change in free volume of interaction will determine how the association will respond to changes in polymerization pressure [82]. Finally, the solvent s interaction with the monomer-template assemblies relative to the free species indicates how well it will stabilize the monomer-template assemblies in solution [16]. Here each system must be optimized individually. Another option is simply to increase the concentration of the monomer or the template. In the former case, a problem is that the crosslinking as well as the potentially nonselective binding will increase simultaneously. In the... 

However, it was found that the effect on the equilibrium formation of aromatics is not substantial due to thermodynamic considerations. A more favorable effect was found for the reaction between ethylene (formed via cracking during aromatization of propane) and hydrogen. The reverse shift reaction consumes hydrogen and decreases the chances for the reduction of ethylene to ethane byproduct. 

It follows from the electrochemical mechanism of corrosion that the rates of the anodic and cathodic reactions are interdependent, and that either or both may control the rate of the corrosion reaction. It is also evident from thermodynamic considerations (Tables 1.9 and 1.10) that for a species in solution to act as an electron acceptor its redox potential must be more positive than that of the M /M equilibrium or of any other equilibrium involving an oxidised form of the metal. 

In the electrochemical series of elements, copper is near the noble end and will not normally displace hydrogen, even from acid solutions. Indeed, if hydrogen is bubbled through a solution of copper salts, copper is slowly deposited (more rapidly if the process is carried out under pressure). (See Section 1.2 for thermodynamic considerations.)... 

The close molecular packing makes diffusion more difficult than with amorphous polymers compared in similar circumstances, i.e. both below Tg or both above (but below of the crystalline polymer). Thermodynamic considerations lead to considerable restriction in the range of solvents available for such polymers. 

It is possible to indicate by thermodynamic considerations 24,25,27>, by spectroscopic methods (IR28), Raman29 , NMR30,31 ), by dielectric 32> and viscosimetric measurements 26), that the mobility of water molecules in the hydration shell differs from the mobility in pure water, so justifying the classification of solutes in the water structure breaker and maker, as mentioned above. 

In addition to the questions of the potentials and capacities of electrodes, which are essentially thermodynamic considerations, practical utilization of alloys as electrodes also requires attractive kinetic properties. 

For example, disproportionation of but-2-yl radicals produces a mixture of butenes as shown (Scheme 1.1 I).138 Thermodynamic considerations suggest thai but-l-ene and but-2-enes should be formed in a ratio of ca 2 98. However, the observed 5 4 ratio of but-1-ene but-2-enes is little different from the 3 2 ratio that is expected on statistical grounds (i.e. ratio of f5-hydrogens in the I- and 3-positions). 

Continuous transition of state is possible only between isotropic states it may thus occur between amorphous glass (i.e., supercooled liquid of great viscosity) and liquid ( sealing-wax type of fusion ), or between liquid and vapour, but probably never between anisotropic forms, or between these and isotropic states. This conclusion, derived from purely thermodynamic considerations, is also supported by molecular theory. 

The investigation above is due initially to Gibbs (Scient. Papers, I., 43—46 100—134), although in many parts we have followed the exposition of P. Saurel Joum. Phys. diem., 1902, 6, 474—491). It is chiefly noteworthy on account of the ease with which it permits of the deduction, from purely thermodynamic considerations, of all the principal properties of the critical point, many of which were rediscovered by van der Waals on the basis of molecular hypotheses. A different treatment is given by Duhem (Traite de Mecanique chimique, II., 129—191), who makes use of the thermodynamic potential. Although this has been introduced in equation (11) a the condition for equilibrium, we could have deduced the second part of that equation directly from the properties of the tangent plane, as was done by Gibbs (cf. 53). 

Basic thermodynamic considerations may be used to establish the phase diagram of a ternary system consisting of liquid components 1 and 3 and supercritical gas 2. In the subsequent discussion we follow the simplified treatment given by Balder (Bl). 

When m < mc, product assemblages are unstable and thermodynamic considerations predict that the product (B) will tend to revert to the reactant unless the local statistical fluctuations of energy are sufficient to achieve... 

Pyrolyses of formates, oxalates and mellitates yield CO and C02 (H2, H20 etc.) as the predominant volatile products and metal or oxide as residue. It is sometimes possible to predict the initial compositions from thermodynamic considerations [94], though secondary reactions, perhaps catalyzed by the solids present, may result in a final product mixture that is very different. The complex mixtures of products (hydrocarbons, aldehydes, ketones, acids and acid anhydrides) given [1109] by reactants containing larger organic groupings makes the collection of meaningful kinetic data more difficult, and this is one reason why there are relatively few rate studies available for the decompositions of these substances. 

It will now be shown from purely thermodynamic considerations that for, adiabatic conditions, supersonic flow cannot develop in a pipe of constant cross-sectional area because the fluid is in a condition of maximum entropy when flowing at the sonic velocity. The condition of the gas at any point in the pipe where the pressure is P is given by the equations ... 

The Feasibility of the Desolvation Hypothesis Can Be Examined with Clear Thermodynamic Considerations... 

I. Metcalfe, Electrochemical Promotion of Catalysis I Thermodynamic considerations, J. Catal. 199,247-258 (2001). 

Hoffman, M. R. (1981). Thermodynamic, kinetic and extra-thermodynamic considerations in the development of equilibrium models for aquatic systems. Environ. Sci. Technol. 15,345-353. 

Hastings, D. and Emerson, S. (1986). Oxidation of manganese by spores of a marine Bacillus Kinetics and thermodynamic considerations. Geochem. Cosmochim. Acta 50,1819-1824. 

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