Partitioning temperature dependence

LFERs Relating Partition Constants in Different Air-Solvent Systems Model for Description of Air-Solvent Partitioning Temperature Dependence of Air-Organic Solvent Partition Constants Applications... 

Thermodynamics of complex formation, discussed in detail by Schmidtchen in the present volume, hold many surprises.[32] In comparing enthalpic with entropic parameters one should not forget that AG and AS depend on the chosen units for relative concentration, which can be either mol/1, or can be given in dimensionless mole fractions in consequence the usual partition of absolute numbers for AH and AS becomes to some degree arbitrary (see e.g. ref. 2d, p. 24, p. 106). In addition, complexation is usually characterized by sizeable changes of heat capacity, making the thermodynamic partitions temperature-dependent. 

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)). 

Thus, A is apparently temperature dependent, but not highly so, because the partition functions are not very sensitive functions of temperature. 

The model [39] was developed using three assumptions the conformers are in thermodynamic equilibrium, the peak intensities of the T-shaped and linear features are proportional to the populations of the T-shaped and linear ground-state conformers, and the internal energy of the complexes is adequately represented by the monomer rotational temperature. By using these assumptions, the temperature dependence of the ratio of the intensities of the features were equated to the ratio of the quantum mechanical partition functions for the T-shaped and linear conformers (Eq. (7) of Ref. [39]). The ratio of the He l Cl T-shaped linear intensity ratios were observed to decay single exponentially. Fits of the decays yielded an approximate ground-state binding... 

Table 3.5. The number of degrees of freedom in translation, rotation and vibrations of the reacting molecules and the transition state in the gas phase reaction of CO and O2 and the temperature dependence these modes contribute to the partition function. Note that one of the modes of the transition state complex is the reaction coordinate, so that only six vibrational modes are listed.

Note that if the ratio of partition functions in Eq. (189) leaves a nonvanishing temperature dependence, it generates the additional terms ksTin a and factors e in hv. Consequently, the prefactor hv strongly depends on the nature of the transition state. 

Especially for temperature-dependent partition processes, besides temperature-influenced humidity of the vapor phase, a thermostat device is recommended for development. The Baron TEC thermobox 200 and Desaga TEC thermobox respectively (Figure 5.25) can be adapted to suit current development chambers using a variable covering mask. A Peltier element with integrated temperatnre control... 

Stannite is the most common tin sulfide mineral in the ore deposits associated with tin mineralization. This mineral sometimes contains appreciable amounts of zinc, together with iron. Several workers have suggested that the zinc and iron contents of stannite are related to temperature. With respect to the study of the phase relationships in the pseudobinary stannite-kesterite system. Springer (1972) proposed zincic stannite as a possible geothermometer mainly based on the chemical compositions of the two exsolved phases (stannite and kesterite). Nekrasov et al. (1979) and Nakamura and Shima (1982) experimentally determined the temperature dependency of iron and zinc partitioning between stannite and sphalerite. 

Nekrasov et al. (1979) and Nakamura and Shima (1982) reported a temperature dependency of iron and zinc partitioning between stannite and sphalerite (Fig. 1.177)... 

Bercovici D, Lin J (1996) A gravity current model of cooling mantle plume heads with temperature dependent buoyancy and viscosity. J Geophys Res 101 3291-3309 Blundy J, Wood B (1994) Prediction of crystal-melt partition coefficients from elastic moduh. Nature 372 452-454... 

Kaufman, J. J. Semo, N. M. Koski, W. S., Microelectrometric titration measurement of the pKa s and partition and drug distribution coefficients of narcotics and narcotic antagonists andtheirpH and temperature dependence, 7. Med. Chem. 18,647-655 (1975). 

In the second line, we have carried the integral over the ideal gas part, which results in the temperature-dependent de Broglie wavelength, A. The final expression is similar to the familiar casting of the canonical partition function,... 

A useful feature of the multiple-temperature dependence of the partition function Qf / i. 7 j. Tm) in the equation above is that it can be subsequently manipulated... 

All partitioning properties change with temperature. The partition coefficients, vapor pressure, KAW and KqA, are more sensitive to temperature variation because of the large enthalpy change associated with transfer to the vapor phase. The simplest general expression theoretically based temperature dependence correlation is derived from the integrated Clausius-Clapeyron equation, or van t Hoff form expressing the effect of temperature on an equilibrium constant Kp,... 

Reported Henry s law constants and octanol-air partition coefficients of n-pentane at various temperatures and temperature dependence equations... 

Dewulf, J., van Langenhove, H., Grare, S. (1999) Sediment/water and octanol/water equilibrium partitioning of volatile organic compounds temperature dependence in the 2-25°C range. Water Res. 33, 2424—2436. 

Finizio, A., Di Guardo, A. (2001) Estimating temperature dependence of solubility and octanol-water partition coefficient for organic... 

Octanol/Air Partition Coefficient, log KqA at 25°C or as indicated and reported temperature dependence equation. Additional data at other temperatures designated are compiled at the end of this section ... 

Octanol/Water Partition Coefficient, log KqW at 25°C and reported temperature dependence equations ... 

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