Mixing ideal gases

Note that this has resulted in the separation of pressure and composition contributions to chemical potentials in the ideal-gas mixture. Moreover, the themiodynamic fiinctions for ideal-gas mixing at constant pressure can now be obtained ... 

Ideal Gas Mixing Properties at Constant Temperature and Partial Pressure of Each Species... 

Ideal Gas Mixing. When C species are mixed at constant pressure and temperature, as illustrated in Figure 9.9. the change in the entropy flow rate is given by Eg. 19.10). applied separately for each species j ... 

A third case arises when a mixed gas is in equilibrium with immiscible pure liquid or solid phases. The vapor pressure of each condensed phase is then unaffected by the existence of the mixed vapor phase. Each pure condensed phase communicates only with its own partial pressure. This results in a total pressure that is the sum of the two vapor pressures, as illustrated above for ideal gas mixing pi = njRTA t, and... 

Density, thermal conductivity and dynamic viscosity properties for gas mixtures are calculated with the assumption of ideal gas mixing, expressed as follows ... 

The foregoing discussion has dealt with nonideahties in the Hquid phase under conditions where the vapor phase mixes ideally and where pressure-temperature effects do not result in deviations from the ideal gas law. Such conditions are by far the most common in commercial distillation practice. However, it is appropriate here to set forth the completely rigorous thermodynamic expression for the Rvalue ... 

Witlox, H. W. M., 1993, Thermodynamics Model for Mixing of Moist Air with Pollutant Consisting of HF, Ideal Gas, and Water, Shell Research Limited, Thornton Research Center, TNER.93.021,. 

Also of importance is the effect of temperature on the gas solubility. From this information it is possible to determine the enthalpy and entropy change experienced by the gas when it changes from the ideal gas state (/z and ) to the mixed liquid state ( andT,). 

Figure 2.13 Mixing of ideal gas A with ideal gas B at constant temperature and constant total pressure. The entropy change AS is given by equation (2.78).

The entropy changes ASa and ASB can be calculated from equation (2.69), which applies to the isothermal reversible expansion of ideal gas, since AS is independent of the path and the same result is obtained for the expansion during the spontaneous mixing process as during the controlled reversible expansion. Equation (2.69) gives... 

E2.12 Calculate ASmiX for the mixing of 0.25 moles of D2 (deuterium gas) with 0.75 moles of H2 at a total constant pressure of 100 kPa. Assume ideal gas behavior. 

Obtain m> expression for the concentration of gas A in that half of she pipe in which it is increasing, as a (unction of distance y from the valve and time t after opening. The whole system is at a constant pressure and the ideal gas law is applicable to both gases. It may be assumed that the rate of mixing in the vessels is high so that the gas concentration at the two ends of the pipe do not change. 

The volume of an ideal gas mixture is given by eq. (3.6). Let us now consider only solid or liquid mixtures. Our starting point is an arbitrary mixture of nA mole of pure A and ng mole of pure B. The mixing process is illustrated in Figure 3.1. We... 

In this equation x, is the liquid perfume concentration, Mt the molecular weight, R the ideal gas constant, and T the absolute temperature. Equation 2 relates the liquid perfume composition, x, with the human sensory reaction of the evaporated perfume. A key factor of Equation 2 is the activity coefficient, y, because it represents the affinity of a molecule to its neighboring medium. High value of y means an increased inclination for a given substance to be released from the mixture and low value of y means a low concentration in the headspace. This means that the OV values of a particular component can change if it is diluted in different solvents or mixed with different fragrance components. 

Similarly, we obtained the chemical potential of a component of an ideal gas mixture as [Equation (10.17)] from an analysis of the van t Hoff mixing experiment, using the same integral. 

The atmospheric composition information in Table 6.1 is presented as the volume mixing ratio for each gas (1a/ r)- At a constant temperature and pressure, the ideal gas law can be used to show that... 

Mass and energy transport occur throughout all of the various sandwich layers. These processes, along with electrochemical kinetics, are key in describing how fuel cells function. In this section, thermal transport is not considered, and all of the models discussed are isothermal and at steady state. Some other assumptions include local equilibrium, well-mixed gas channels, and ideal-gas behavior. The section is outlined as follows. First, the general fundamental equations are presented. This is followed by an examination of the various models for the fuel-cell sandwich in terms of the layers shown in Figure 5. Finally, the interplay between the various layers and the results of sandwich models are discussed. 

Other common ways of expressing abundances, particularly of solid or liquid particles, is to express them as concentrations in units of micrograms per cubic meter or nanomoles per cubic meter. For purposes of consistency, concentrations expressed in these units should be normalized to standard conditions of temperature and pressure. Because there is some confusion as to what constitutes standard conditions in atmospheric chemistry (273 K and 1.013 bar are commonly used in chemistry and physics and 293 K and 1.013 bar are used in engineering), it is important to define the standard conditions that are assumed when reporting data. This explicit definition is frequently not done. Concentrations expressed in these units can be easily converted to mixing ratios by use of the ideal gas law ... 

A tank contains methane at 1000 psia and MOT. Another tank of equal volume contains ethane at 500 psia and MOT. The two tanks are connected, the gases are allowed to mix, and the temperature is restored to MOT. Calculate the final pressure, the composition of the mixture, and the partial pressures of the components at final conditions. Do not assume that ideal gas equations apply. 

There are no ideal liquid solutions, just as there are no ideal gas mixtures. However, when liquids of similar chemical and physical characteristics are mixed, the behavior of the resulting solution is very much like the behavior of an ideal solution. Fortunately, most of the liquid mixtures encountered by petroleum engineers are mixtures of hydrocarbons with similar characteristics. Thus, ideal-solution principles can be applied to the calculation of the densities of these liquids. 

---