Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. Includes bibliographical references (leaves 213-218).

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 135-137).

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Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 15, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering and Medical Sciences, Departments of Chemical and Materials Engineering and Medical Sciences - Laboratory Medicine and Pathology, University of Alberta. Includes bibliographical references.

Many bulk properties of gases depend linearly on the gas density at lower densities, but as the density increases departures from linearity are observed. The density dependence of a bulk property Q may often be discussed systematically by expanding Q as a power series in l/Vm, to yield: Q=Aq+Bq/Vm+Cq/V2m+..., where Bq is known as the second virial coefficient of the property Q. Aq is the ideal gas value of Q, and Bq describes the contribution of molecular pair interactions to Q. Theories of Q may be regarded as having two main components, one describing how the presence of a neighbour of a given molecule can enhance or detract from its contribution to Q, and the other the molecular interaction energy which determines the average geometry of a pair encounter. The latter component is common to all theories, and the former requires detailed derivations for each specific bulk property Q. In this work we consider the second virial coefficients of five effects, namely the second pressure virial coefficient B(T), and also the second dielectric, refractivity, Kerr-effect and light-scattering virial coefficients, Be, Br, Bk, and Bp, respectively. Using a powerful computer algebraic manipulation package we have extended the existing dipole-induced-dipole (DID) theories of the second dielectric, refractivity and Kerr-effect virial coefficients to sufficiently high order to establish convergence in the treatment of both linear and non-linear gases. Together with the established linear theory of the second pressure virial coefficient, the extended theory of the second light- scattering virial coefficient developed by Couling and Graham, and their new non-linear theory of the second pressure and light-scattering virial coefficients, our new theories provide a comprehensive base from which to calculate numerical values for the various effects for comparison with experiment. We have collected as much experimental data of the various second virial coefficients as possible, for a wide range of gases. The ten gases chosen for detailed study comprise a selection of polar and non-polar, linear and non-linear gases: the linear polar gases fluoromethane, trifluoromethane, chloromethane and hydrogen chloride; the non-polar linear gases nitrogen, carbon dioxide and ethane; the non-linear polar gases sulphur dioxide and dimethyl ether; and the non-linear non-polar gas ethene. Using the best available measured or calculated molecular parameter data for these gases, together with the complete theories for the second virial coefficients, we have attempted to find unique sets of molecular parameters for each gas which explain all the available experimental data. In general, reliable measured or calculated molecular properties are regarded as fixed, and only the Lennard-Jones and shape parameters in the molecular interaction energy are treated as best-fit parameters within the constraints of being physically reasonable. Many of the apparent failures of second virial coefficient theories have been due to the lack of convergence in the series of terms evaluated. It is essential to work to sufficiently high orders in the polarizabilities and various multipole moments to ensure convergence for meaningful comparison with experiment. This often requires the manipulation of extremely long and complicated expressions, not possible by the manual methods of our recent past. The advent of computer manipulation packages and fast processors for numerical integration have now enabled calculation to high orders, where the degree of convergence can be sensibly followed. Our efforts to describe all of the effects for which data is available met with mixed success. For four of the gases, fluoromethane, chloromethane, dimethyl ether and ethene, a unique parameter set was found for each which described all of the available effects reasonably well. For the three gases, trifluoromethane, nitrogen and sulphur dioxide, one interaction parameter set explained all but one of the effects for which data was available to within experimental uncertainty. For trifluoromethane the parameter set which yielded good agreement for B(T), Be, and Bk could not explain the observed values of Br, while for nitrogen one parameter set produced reasonable agreement for all of the effects except Bp and a different set, which yielded good agreement for Bp, did not explain the remaining four effects as well as the first set. The parameter set which explained B(T), Bk and Bp very well for sulphur dioxide, yielded a value for Be, which was much larger than the experimental value, although of the correct sign and order of magnitude. Hydrogen chloride posed a special problem as data was only available for two of the effects, B(T) and Be. It was possible to find a set of interaction parameters in good agreement with the measured values of B(T), but the experimental data for Be was an order of magnitude larger than the largest calculated values. Since the remaining effects have not been measured for this gas it was not possible to test the theory more rigorously. For the remaining gases carbon dioxide and ethane, it was impossible, based on the existing measured values, to select a unique parameter set which explained all of the effects. In many of the cases where definite conclusions could not be drawn, it was not possible to decide whether the disagreement between theory and experiment was due to the large scatter and uncertainty of the experimental data or failure of the theory. However, there were very few instances of complete failure of the theory to explain experiment, and no one effect showed consistent disagreement, so that in general it may be said that the mechanisms of the second virial coefficients under study are reasonably well understood. It would require more precise measurements of the various effects, as well as more measured or calculated molecular property tensor components, such as the hyperpolarizability and the A- and C-tensors , to test the DID molecular interaction model more stringently. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1997.

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Orientador: Adalberto Bono Maurizio Sacci Bassi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T03:59:51Z (GMT). No. of bitstreams: 1 Guerrero_AndredeOliveira_M.pdf: 4353295 bytes, checksum: a8e573ea1fa805457349a7a1d9c37925 (MD5) Previous issue date: 2010 / Resumo: A equação original de van der Waals é alterada de modo a aprimorar sua aderência a dados experimentais para o Argônio, desde as baixas densidades dos estados gasosos até as altas densidades dos líquidos e dos vidros. Isto permite a obtenção de uma curva spinodal (fronteira termodinâmica entre os estados não acessíveis pela matéria e os estados possíveis, estáveis ou não) mais precisa do que a atualmente disponível, além de fornecer subsídios para estudos de líquidos e gases não estáveis. A pressão repulsiva original é substituída pela pressão de um sistema de esferas rígidas, enquanto que a pressão atrativa original é substituída pela pressão de um campo médio isotrópico descrito por três parâmetros. A realização destas alterações propicia a discussão de diversos aspectos da interpretação física da equação de van der Waals. Como os estados considerados são homogêneos, mas não necessariamente estados de equilíbrio, a temporal termodinâmica dos meios homogêneos é uma teoria adequada à descrição dos estados representados pela equação alterada. / Abstract: The original van der Waals equation is altered to improve its quantitative description of argon experimental values, including those of low density gaseous states and high density liquids and glasses. A spinodal curve is obtained (the limit between thermodynamically forbidden and permitted states of matter, either stable or unstable) that is more precise than the one actually available and reveals more information for studying unstable gases and liquids. The pressure of a rigid spheres system substitutes the original repulsive pressure, while the pressure of an isotropic mean field defined by three parameters substitutes the original attractive pressure. Implementing these substitutions provokes the discussion of several aspects, related to the physical meaning of van der Waals equation. Since only homogeneous states are considered, although they are not necessarily equilibrium states, time dependent thermodynamics of homogeneous media is an adequate theory to describe the states represented by the altered equation. / Mestrado / Físico-Química / Mestre em Química

Orientador: Adalberto Bono Maurizio Sacchi Bassi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T13:03:52Z (GMT). No. of bitstreams: 1 Florindo_CaioCesarFerreira_M.pdf: 1544899 bytes, checksum: 0eba46471eda7b3f002b978841cb2411 (MD5) Previous issue date: 2012 / Resumo: O presente trabalho tem três metas principais: (1) usar as transformações de Levin para estimar coeficientes viriais e avaliar a qualidade das estimativas; (2) inserir adaptações, coerentes com as transformações de Levin, na equação original de van der Waals, de modo a aprimorar sua capacidade de se aproximar de dados experimentais para estados estáveis; (3) extrapolar a equação adaptada, para possibilitar o estudo de estados não estáveis. Os resultados indicam que as transformações de Levin podem ser usadas como uma forma aproximada de representar a série virial, porque os coeficientes viriais de alta ordem, por elas estimados, estão em boa concordância com os valores obtidos na literatura. A utilização das representações de Levin para a adaptação do termo repulsivo da equação de van der Waals, juntamente com uma alteração proposta para o termo atrativo, produz isotermas subcríticas e supercríticas em boa concordância com os dados experimentais e proporciona aprimoramento da previsão do comportamento do sistema. As novas equações podem ser aplicadas tanto em densidades referentes à região de fase gasosa, como de fase líquida. Devido às boas previsões de resultados produzidas pelas equações desenvolvidas neste trabalho, são obtidas curvas spinodais com um nível de exatidão muito superior àquele encontrado na literatura. Portanto, o presente trabalho descreve equações aprimoradas que representam estados estáveis tão bem que podem ser extrapoladas para estados não estáveis / Abstract: This work aims at three main goals: (1) to use Levin's sequence transformations for estimating virial coefficients, and to assess the quality of the estimates; (2) to insert in the van der Waals equation some modifications consistent with the Levin's sequence transformations, enhancing its ability to approximate experimental data for stable states; (3) to extrapolate the modified equation for studying unstable states. The results indicate that the Levin's sequence transformations can be used as an approximate way to represent the virial series, because the high order estimated virial coefficients are in good agreement with values reported in literature. The use of the Levin's sequence transformations for modifying the repulsive term of van der Waals equation, together with a proposed attractive term improvement, yields subcritical and supercritical isotherms in good agreement with experimental data and provides better predictions of the behavior of the system. The new equations can be applied both at densities corresponding to gaseous and liquid phases. According to the good predictions of experimental results produced by the equations developed in this work, spinodal curves which are much more accurate than those found in literature are obtained. Therefore, this work describes improved equations that represent stable states well enough to accept extrapolation to unstable states / Mestrado / Físico-Química / Mestre em Química