Temperature dependences constant

Furthermore, most physicochemical properties are related to interactions between a molecule and its environment. For instance, the partitioning between two phases is a temperature-dependent constant of a substance with respect to the solvent system. Equation (1) therefore has to be rewritten as a function of the molecular structure, C, the solvent, S, the temperature, X etc. (Eq. (2)). 

In this expression / is the ionic strength of the. solution and A is a temperature-dependent constant (0.5112 mol 2 at... 

A = temperature-dependent constant characteristic for a homologous series... 

The product of the molar concentrations (or, more accurately, the activities) of the species produced as a result of autoprotolysis. The autoprotolysis constant for water is K, equal to [H30+][0H ], or 1.0 x IQ i at 25°C. It is a temperature-dependent constant, increasing with... 

The term A is a temperature-dependent constant. Values of A between 0 and 60 °C are given in Table 7.3. 

Here the pre-exponential factor At is the product of a temperature-dependent constant (ksT/h) = 2 X 10 °Ts where ke and h are the Boltzmann and Planck constants, and a solvent-specific coefficient that relates to both the solvent viscosity and to its orientational relaxation rate. This coefficient may be near unity for very mobile solvent molecules but may be considerably less than unity for viscous or orientationally hindered highly stractured solvents. The exponential factor involves the activation Gibbs energy that describes the height of the barrier to the formation of the activated complex from the reactants. It also describes temperature and pressure dependencies of the reaction rate. It is assumed that the activated complex is in equilibrium with the reactants, but that its change to form the products is rapid and independent of its environment in the solution (de Sainte Claire et al., 1997). 

To applying Eq. (2.47) to non-isothermal problems, it is necessary to generalize it by introducing temperature-dependent constants. The basic approach was proposed by Ziabicki94,95 who developed a quasi-static model of non-isothermal crystallization in the form of a kinetic rate equation ... 

Ion product — A temperature-dependent constant related to pure substances that can dissociate forming ions and remain in equilibrium with them. It is the product of the ion activities raised to the stoichiometric coefficients of such ionic species in former pure substance. Since the concentration of the pure substance is practically a constant, it is not included in this equilibrium expression. Common pure substances characterized by an ion-product constant are -> amphiprotic solvents, and those salts that are partially dissolved in a given solvent. In the latter case, the ion product is synonymous with solubility product. The following table (Table 1) summarizes self-ionization ionic products and - autoprotolysis constants of some - amphiprotic solvents [i]. 

Rate of electron transfer in energy yielding reactions is a temperature-dependent constant for all microorganisms. 

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