Mixtures in Gravitational and Centrifugal Fields

Substance i in a liquid or solid Pi = exp ( / dp exp mixture, or the pure liquid or solid 

In principle, we can specify any convenient value for the standard pressure p°. For a chemist making measurements at high pressures, it would be convenient to specify a value of within the range of the experimental pressures, for example p° = 1 kbar, in order that the value of each pressure factor be close to unity. 

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In this volume, we will apply the principles developed in Principles and Applications to the description of topics of interest to chemists, such as effects of surfaces and gravitational and centrifugal fields phase equilibria of pure substances (first order and continuous transitions) (vapor + liquid), (liquid 4-liquid), (solid + liquid), and (fluid -f fluid) phase equilibria of mixtures chemical equilibria and properties of both nonelectrolyte and electrolyte mixtures. But do not expect a detailed survey of these topics. This, of course, would require a volume of immense breadth and depth. Instead, representative examples are presented to develop general principles that can then be applied to a wide variety of systems. 

Consider then a mixture of A and B which are being subjected to a uniform gravitational acceleration or centrifugal acceleration g in the — z direction. It should be noted that there is no mass flux due to forced diffusion according to Eq. (35) inasmuch as jt(F) vanishes when we replace t by —g. The effect of the gravitational field is to produce a pressure gradient, the latter being determined by Eq. (25), which for the case under consideration becomes ... 

A tall column of a gas mixture in a gravitational field, and a liquid solution in the cell of a spinning centrifuge rotor, are systems with equilibrium states that are nonuniform in pressure and composition. This section derives the ways in which pressure and composition vary spatially within these kinds of systems at equilibrium. 

Section 7.3 covers separation operations/processes/ techniques in which an external force field is applied perpendicular to the direction of bulk flow of a singlephase solution or a dispersed/particulate multiphase mixture (Figures 7.0.1(i)-(p)). The external force fields considered are electrical, centrifugal, gravitational and magnetic. Specific processes treated include, among others, electrophoresis (Figure 7.0.1(i)), dielectrophoresis. 

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