Equilibrium gas phase composition

GRA/H1R] Grade, M., Hirschwald, W., Equilibrium gas phase composition of IIB/VIA compounds and identification of gaseous MeX(g) molecules, Z. Anorg. Allg. Chem., 460, (1980), 106-114. Cited on page 279. 

The activity coefficients and the equilibrium gas-phase composition have been calculated by using relationships based on Dalton s law. This also applies to Duhem s equation in the form of Eq. (8.22). For the water HP system this approach is approximately valid at T < 520 K. Comparison of activity coefficients and gas-phase composition obtained within the Redlich-Kister approximations and by numerical integration of Eq. (8.22) indicates that the modified approach of Eq. (8.23) agrees well with the solution of Eq. (8.22). With this modification, Eqs. (8.8), (8.9), (8.17), (8.18), and (8.23) provide the explicit and fairly accurate dependencies of activity coefficients on solution composition and temperature. Based on the activity coefficients, gas-phase composition can be readily obtained by using the approximations for the total pressure and Eqs. (8.3) and (8.4). Application of these formulae for estimating activity coefficients and gas-phase concentrations at higher temperatures [T > 520 K) should be considered as extrapolation. The accuracy of this extrapolation can be worse as compared to total pressure calculations. 

The approaches for calculating equilibrium gas-phase composition in a two-phase system containing aqueous solution of HP. air, and JPF are also suggested. The further step in evaluating the performance of the dual-fuel, air-breathing PDE [13] is to incorporate chemical kinetics of HP decomposition and JPF oxidation. Preliminary results on simulation of JPF (or HP) liquid drop ignition and combustion in air with HP (or JPF) vapor have been reported [16]. 

Equilibrium Gas Phase Composition. Having defined optimum proportioning of reformed gas and sulfur dioxide and having specified... 

A COMPARISON OF METHODS OF PREDICTING EQUILIBRIUM GAS PHASE COMPOSITIONS IN PRESSURIZED BINARY SYSTEMS CONTAINING AN ESSENTIALLY PURE CONDENSED PHASE... 

B. S. Kirk, W.T. Ziegler, and J.C. Mullins, "A Comparison of Methods of Predicting Equilibrium Gas Phase Compositions in Pressurized Systems Containing an Essentially Pure Condensed Phase." Advances in Cryogenic Engineering, Vol. 6, K.D. Timmerhaus (ed.), Plenum Press, Inc., New York, 1961. 

Laboratory column experiments were used to investigate the interactions between selected liner materials and the spiked leachate. A schematic of the experimental set-up is presented in Fig. 1. The apparatus supplied freshwater and leachate to the columns under conditions isolated from the atmosphere. The leachate was stored anaerobically under a 50 50 C02 N2 atmosphere in sealed, refrigerated tanks at 4°C to minimize compositional changes (Korte et al. 1976). A gas pressure of 30kPa was used to supply leachate to the experimental columns and the apparatus is designed to transfer leachate out of the active tanks (A and B) only. The passive tanks (P) provide an equilibrium gas phase composition of volatile organic fractions which is transferred to the active tanks. This gas phase... 

Y = Mol fraction of one component (solute) at any point in the gas phase Y = Mol fraction gas phase composition in equilibrium with a liquid composition, X... 

When the standard states for the solid and liquid species correspond to the pure species at 1 atm pressure or at a low equilibrium vapor pressure of the condensed phase, the activities of the pure species at equilibrium are taken as unity at all moderate pressures. Consequently, the gas phase composition at equilibrium will not be... 

Solid-Phase Chemical Equilibrium. For the growth of multicomponent films, the solid film composition must be predicted from the gas-phase composition. In general, this prediction requires detailed information about transport rates and surface incorporation rates of individual species, but the necessary kinetics data are rarely available. On the other hand, the equilibrium analysis only requires thermodynamic data (e.g., phase equilibrium data), which often are available from liquid-phase-epitaxy studies, as discussed by Anderson in Chapter 3. 

Equilibrium measurements of the solid hydrate phase have been previously avoided due to experimental difficulties such as water occlusion, solid phase inhomogeneity, and measurements of solid phase concentrations. Instead, researchers have traditionally measured fluid phase properties (i.e., pressure, temperature, gas phase composition, and aqueous inhibitor concentrations) and predicted hydrate formation conditions of the solid phase using a modified van der Waals and Platteeuw (1959) theory, specified in Chapter 5. 

A value for the reversibility B can easily be found if the equilibrium constant of the brutto-reaction and the gas phase composition are known. 

However, for mixtures of TPP and toluene, a third (liquid) phase forms in the presence of the gas and the solid, at pressures well below the critical pressure of toluene. At higher pressures, gas-liquid and solid-liquid equilibria were observed, rather than gas-solid equilibrium. Thus, phase compositions for gas-liquid equilibrium were measured for this binary mixture to give TPP solubilities in each of the fluid phases. Pressures and temperatures for three-phase, solid-liquid-gas equilibrium were also measured for both binary mixtures. 

Bubble points for gas-liquid equilibrium were measured at constant temperature by observing the pressure at which the equilibrium gas phase disappeared upon injection of small amounts of solvent into the view cell. The equilibrium composition of the liquid phase was obtained from the known composition in the cell. Other pressures and corresponding compositions at this temperature were obtained by repeating the procedure for different porphyrin loadings. 

The problem we are addressing here is what is the gas phase composition of a mixture of gases under specified conditions of pressure and temperature, where as much time as is necessary is allowed for the gases to equilibrate If there is a change of phase as one proceeds from one equilibrium state to another (i.e., solid silicon film forming on the container walls), then this has to be accounted for as well. 

In some liquid-vapour equilibrium experiments with low iodine contents (Larousse, 2009), an unexpected decrease of the pressure with time, especially at elevated temperatures, is observed (Figure 3). A possible, though not proven, explanation would be HI decomposition with condensation of the resulting I2 in the liquid phase, just like what is anticipated to take place in the reactive distillation column. However, the observed kinetics are about 105 faster than what is expected from gas phase composition, which could be an indication of liquid phase decomposition. 

The ratio of the two reactions is determined by the gas-phase composition through the equilibrium... 

Closure of such differential equations requires the definitions of both constitutive relations for hydrodynamical functions and also kinetic relations for the chemistry. These functions are specified by recourse both to theoretical considerations and to rheological measurements of fluidization. We introduce the ideal gas approximation to specify the gas phase pressure and a caloric equation-of-state to relate the gas phase internal energy to both the temperature and the gas phase composition. It is assumed that the gas and solid phases are in local thermodynamic equilibrium so that they have the same local temperature. 

Table II gives the results of thermodynamic calculations of the composition of the equilibrium gas phase in the system C-H-N-O for different ratios of carbon and nitrogen (the inert gases were not taken into account). The following reactions were analyzed ...

A gas containing nitrogen, benzene, and toluene is in equilibrium with a 40 mole% benzene-60 mole% toluene liquid mixture at 100 C and 10 atm. Estimate the gas-phase composition (mole fractions) using Raoult s law. 

Using Raoult s law or Henry s law for each substance (whichever one you think appropriate), calculate the pressure and gas-phase composition (mole fractions) in a system containing a liquid that is 0.3 mole% N2 and 99.7 mole% water in equilibrium with nitrogen gas and water vapor at SOX. 

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