Vaporization Gibbs energy

If such calculations are repeated for a wide range of temperatures and pressures, it is observed that the angle of intersection 6 between the liquid and vapor Gibbs energy curves decreases as the pressure (and temperature) at which the intersection occurs increases (provided P < Pc). At the critical pressure, the two Gibbs energy curves intersect, with 6 = 0 that i.s, the two curves are collinear for some range of T around the critical temperature 77.. Thus, at the critical point,... 

An overview of some basic mathematical techniques for data correlation is to be found herein together with background on several types of physical property correlating techniques and a road map for the use of selected methods. Methods are presented for the correlation of observed experimental data to physical properties such as critical properties, normal boiling point, molar volume, vapor pressure, heats of vaporization and fusion, heat capacity, surface tension, viscosity, thermal conductivity, acentric factor, flammability limits, enthalpy of formation, Gibbs energy, entropy, activity coefficients, Henry s constant, octanol—water partition coefficients, diffusion coefficients, virial coefficients, chemical reactivity, and toxicological parameters. 

The heat of mixing (excess enthalpy) and the excess Gibbs energy are also experimentally accessible, the heat of mixing by direcl measurement and G (or In Yi) indirectly as a prodiicl of the reduction of vapor/hqiiid eqiiihbriiim data. Knowledge of H and G allows calculation of by Eq. (4-13) written for excess properties. 

Since the system is closed, dtij = 0 and, therefore, dGj = 0 this requires the molar (or specific) Gibbs energy of the vapor to be identical with that of the liquid ... 

Gamma/Phi Approach For many XT E systems of interest the pressure is low enough that a relatively simple equation of state, such as the two-term virial equation, is satisfactoiy for the vapor phase. Liquid-phase behavior, on the other hand, may be conveniently described by an equation for the excess Gibbs energy, from which activity coefficients are derived. The fugacity of species i in the liquid phase is then given by Eq. (4-102), written... 

Harris, K.R., Dunlop, P.J. (1970) Vapor pressures and excess Gibbs energies of mixtures of benzene with chlorobenzene, -hexane and -heptane at 25°C. J. Chem. Thermodyn. 2, 801-811. 

Moisture vapor transmission rate (MVTR), for VDC copolymers, 25 709-710 Molality, 15 751 Molar absorptivity, 14 237 Molar flux, 15 678 Molar Gibbs energy, 24 660, 662 Molarity, 15 751... 

Asmanoca, N. and Goral, M. Vapor pressmes and excess Gibbs energies in binary mrxtmes of hydrocarbons at 313.15 K. 1. Methylcyclohexane-benzene, -toluene, -o-xylene, /rxylene, -ethylbenzene, and -propylbenzene, J. Chem. Eng. Data, 25(3) 159-161, 1980. 

The mutual solubility of two liquids A and B depends, in general, on how much the molecules of each liquid tend to attract those of its own kind, relative to their tendency to attract those of the other. This tendency is measured by the excess Gibbs energy of mixing of the two liquids (see section 2.4), Am gL, which is related to the partial vapor pressures p/ and of the two liquids A and B in the mixture. If the composition of the system is given by and Wb moles of the respective components in a given phase, their mole fractions in this phase are... 

R.B. Cundall et al, "Vapor Pressure Measurements on Some Organic High Explosives , J-ChemSoc, Faraday Trans I, 74 (6), 1339—45 (1978) CA 89, 181933 (1978) [Equilibrium vap press were detd for various expls by the Knudson cell technique. The data for HMX follows the Clausius-Clapeyron eqtn. The values detd for the const A and B in the eqtn, log10p = A—(B/T), plus the std enthalpy, entropy and Gibbs energy of sublimation from the authors calcns are presented in Table 7 ... 

Since the drops have a curved surface of radius r the vapor pressure P/f is higher than that of the flat liquid surface. Thus, the difference in the Gibbs energies is... 

The property known as the Gibbs energy G, and defined by Equation 2.17, plays an important role in describing on the one hand the transformation between phases where species stay the same but distribute differently over the phases present, such as vapor and liquid, and on the other hand in transformations where species change identity, the chemical reaction. Chemical reactions and phase transformations both proceed in the directions that fulfill Equations 2.18 and 2.19. 

De Kruif, C.G., Van Generen, A.C.G., Bink, J.C.W.G., Oonk, H.A.J. (1981) Properties of mixed crystalline organic material prepared by zone levelling. II. Vapor pressures and excess Gibbs energies of (p-dichlorobenzene + />-dibromobenzene). J. Chem. Thermodynam. 13, 457 163. 

But the first two terms on the right are the Gibbs energies of pure liquid i pure vapor r at the pure-species equilibrium conditions T and Pf1 accor to Eq. (6.47), they are equal. The preceding equation therefore reduces to... 

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