Density aqueous phase, calculations

The E, N, and P terms are then obtained from the density matrix P of the aqueous-phase SCF calculation as... 

In a research laboratory, fractal aggregation of emulsion droplets is studied. An O-W emulsion is made with a buffer containing /i-lactoglobulin as the continuous phase. To prevent sedimentation of the droplets, part of the oil is brominated to match the density of the oil phase and the aqueous phase. The droplet diameter obtained is 2 pm, (p = 0.1. To prevent convection currents, the emulsion is stored at precisely 20°C in a thermostat. The emulsion then forms a gel after 2.5 hours. By use of Eq. (13.20), assuming RCI — Rg and Z) = 2, it is calculated that W 10. In order to check the assumptions, it is decided to dilute the emulsion with an equal amount of water it is expected that the gel time will then be 23 times as long, i.e., 20 h. However, this proves incorrect after a month, the emulsion is still liquid. What can be the explanation ... 

The adsorption of the anionic surfactant sodium dodecyl sulphate (SDS), probably the most frequently studied surfactant and often used as model substance at the air/water and at the decane /interface is given in Fig. 1.5. The surface and interfacial tension have been plotted as a function of SDS concentration in the aqueous phase. From the slope of the tangents to the curves in Fig. 1.5 the interfacial excess concentration (adsorption density) F at different interfacial tensions can be calculated directly using Gibbs fundamental adsorption isotherm (see section 2.4.1),... 

This type of layer structure, with a compact inner region and a dilute outer region, was also predicted by self-consistent field theory and by computer simulations. For instance, Monte Carlo simulations show that a dense layer (1-2 nm thick) is present close to the planar interface (74). This layer contained about 70% of the segments. Further out a region of mu eh lower density was found to extent about 10 nm into the aqueous phase. Similar results were obtained by self-consistent field calculations (75), which also showed that the most hydrophilic segments reside predominantly in the outer layer. 

The experiments were carried out following the outlined procedure and yielded a 1-BuOH concentration in water (g/mL). By using the reported density of 1.00 g/mL for the aqueous phase, the weight fraction of 1-BuOH has been calculated. According to Table 14.4 the results of these experiments agree with literature data. The overall composition of the system has been carefully chosen to lie close to the four-phase region of the system in such a way that the volumetric phase ratio is approximately 5 1 1 3 in order of decreasing density. This means that approximately 50% of the system consists of a water-rich phase and... 

Illustration 1. Acetic acid is to be extracted from water by isopropyl ether in a tower packed with carbon Raschig rings, ether dispersed. Flow rates are to be 30 cu. ft./hr. ether, 45 cu. ft./hr. water. Average physical properties are aqueous phase density pc = 63.0 Ib./cu. ft., viscosity mc = 3.1 centipoises ether phase density pD = 45.6 Ib./cu. ft. interfacial tension [Pg.308]

The dipole moment of liquid water was investigated by several authors [92-94]. Silvestrelli and Parrinello calculated dipole moments of a single water molecule (1.87 D), a dimer (2.1 D), a trimer (2.4 D), as well as liquid water (2.95 D) [92]. In a subsequent study with refined methods they obtained a dipole moment of 3.0 D for liquid water from AIMD simulations [93]. In 2004, Kuo and Mundy reported a study of the aqueous liquid-vapor interface where water was simulated in such a fashion that in one simulations box the water molecules moved freely from the dense bulk phase into the low density vapor phase, i.e., the number of molecules surrounding a water molecule changed smoothly [94]. In this study, Kuo and Mundy found a molecular dipole moment at the vapor/liquid interphase of approximately 2.4 D which changed smoothly to a value of 3.0 D in the bulk phase. 

Although styrene monotier condensed with water in the condensing liquid, it was assumed that the contribution of styrene was negligible to calculate z in (1). Also, it was assumed that densities of the SBR particles, aqueous phase and condensate were all equal to 1 gr/ml. 

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