Binary Components

Diffusion is the molecular transport of mass without flow. The diffu-sivity (D) or diffusion coefficient is the proportionality constant between the diffusion and the concentration gradient causing diffusion. It is usually defined by Fick s first law for one-dimensional, binary component diffusion for molecular transport without turbulence shown by Eq. (2-149)... 

Due to the high heats of formation of the binary components, these small values seem to be representative for most of the chalcogenide halides discussed in this article. 

Chapter Eight Binary Components ALCOHOL - AMINE MIXTURE... 

Chapter Eight Binary Components BINARY COMPONENT - QL... 

Binary component Does not apply Methylphosphonic difluoride [676-99-3]... 

EDMP - O, O -ethyl (2-diisopropy-laminoethyl) methylphosphonite, one of the binary components of VX. 

The components, by-products of the reaction or solvents used to facilitate mixing the components may have their own toxic properties and could present additional hazards. They may also change the rate that the binary nerve agent volatilizes or penetrates the skin. Residual components may react with common materials, such as alcohols, to produce other nerve agents. For data on binary components, see the Component Section (C01-C) following information on the individual agents. 

This idea of adapting and using components to produce other components should apply at all levels of development, from business models to components that encapsulate generic problem specifications to assembling binary components to produce a running system. 

Within the two metastable ranges one of the binary components can have an apparent thermodynamic activity larger than 1. The maximum will be reached at x = xgp. In this study x p was derived as a function of W/2.303 RT by iterative procedures using the relevant equations given by Meyering (6 1 ). Subsequently, the thermodynamic activities of the two components were calculated at the extremes which can be reached for variable xsp (Figure 9). Apparently, such high values as log a= 2 are reached only for x > 0.93. 

Since the system is binary (components A and B), we could write another component continuity equation for component B. Let be the concentration of B in moles of B per unit volume. 

Identify three-phase reactions in binary component systems. 

Equation (2.30) shows that the entropy of mixing in a binary component solution is dependent only on the composition (relative number of moles of components) in the solution and is independent of temperature. 

Figure 2.3 Free energy of mixing curves for solid and liquid phases at various temperatures (a-e) and resulting temperature-composition phase diagram for a completely soluble binary component system (f). From O. F. Devereux, Topics in Metallurgical Thermodynamics. Copyright 1983 by John Wiley Sons, hic. This material is used by permission of John Wiley Sons, Inc.

For the unary diagram, we only had one component, so that composition was fixed. For the binary diagram, we have three intensive variables (temperature, pressure, and composition), so to make an x-y diagram, we must fix one of the variables. Pressure is normally selected as the fixed variable. Moreover, pressure is typically fixed at 1 atm. This allows us to plot the most commonly manipulated variables in a binary component system temperature and composition. 

Close examination of a variety of binary component phase diagrams allows us to draw a number of generalizations regarding the spatial relationship between phases in a diagram. These are summarized in Table 2.2. 

Equations (2.40) and (2.41) are the lever rule and can be used to determine the relative amounts of each phase in any two-phase region of a binary component phase diagram. For the example under consideration, the amount of liquid present mrns out to be... 

Three-Phase Transformations in Binary Systems. Although this chapter focuses on the equilibrium between phases in binary component systems, we have already seen that in the case of a entectic point, phase transformations that occur over minute temperature fluctuations can be represented on phase diagrams as well. These transformations are known as three-phase transformations, becanse they involve three distinct phases that coexist at the transformation temperature. Then-characteristic shapes as they occnr in binary component phase diagrams are summarized in Table 2.3. Here, the Greek letters a, f), y, and so on, designate solid phases, and L designates the liquid phase. Subscripts differentiate between immiscible phases of different compositions. For example, Lj and Ljj are immiscible liquids, and a and a are allotropic solid phases (different crystal structures). 

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