Partial pressures of gas species

The flux ofthe other species, /, is calculated by solution-diffusion transport through the solvent phase (4). Assuming a partial pressure of gas species, j, to equal zero on the permeate side, one can write the flux for the Henry s transport mode as ... 

Figure 3. Caicuiated tempcratuie depraidencc of partial pressures of gas species formed from a gas mixture of (aj 0.5 vol.% Clf, in Hj, and d>) 53 vol.% and 47 voJ.% O3 at 37,5 torr. The shaded areas represent ttie approximate gas-phase temperature regimes which can be reached in different diamond CVD methods.l i (Reproduced with permission.)...

The ideal gas law PV = nRT is extremely useful in converting partial pressures of gas species (e.g., in units of atmospheres) into concentrations (e.g., in units of moles/vol, mass/vol, atoms/vol). While the ideal gas law is straightforward, units can cause a significant challenge A good recommendation is to always use SI units when evaluating the ideal gas law. Thus, pressures must be evaluated in units of Pa (Pascals), where 1 atm = 101300 Pa. 

The upstream side partial pressure of gas species 1 is given as... 

D. Rectification in vertical wetted wall column with turbulent vapor flow, Johnstone and Pigford correlation =0.0.328(Wi) Wi P>vP 3000 < NL < 40,000, 0.5 < Ns. < 3 N=, v,.gi = gas velocity relative to R. liquid film = — in film -1 2 " [E] Use logarithmic mean driving force at two ends of column. Based on four systems with gas-side resistance only, = logarithmic mean partial pressure of nondiffusing species B in binary mixture. p = total pressure Modified form is used for structured packings (See Table 5-28-H). 

Mass spectrometry techniques are the most usual and versatile methods for analysis of the gas [90], Here the effusing vapour is ionized by an ionization source and the product analyzed with a mass spectrometer. The different vapour species are identified and the partial pressures of all species determined. The partial pressure of species i of a compound or a solution with a specific composition is at a specific temperature ... 

R ardless of the chemistry, there are some physical constraints on aerosol-gas interactions. Particles must be close to or at equilibrium with respect to the surrounding vapor to exist in air for any substantial period. Thus, the partial pressure of condensed species on particles must be less than or equal to the saturation vapor pressure at atmospheric temperature for stability. As shown later in this chapter, the requirement of low vapor pressure is particularly important to the stability of organic aerosols. 

Henry s constant of the gas represents the ratio between the partial pressure of the species in the gaseous phase and the molar fraction of the species in solution ... 

Equations (1.4), (1.5), and (1.6) can be applied only to single component gas systems. Next, we shall derive the corresponding equations for the mixed gas systems. In a phase under consideration there are many gases designated by 1, 2, 3, 4,. with n, n2, n, n, ..., rii,... moles (the mixed gas system is thermodynamically considered to be one phase except for special cases). The partial pressure of gas i , Pi, is defined as the product of the mole fraction of that species and the total pressure (P), namely... 

The partial pressure of a species in an ideal-gas mixture is equivalent to the mole fraction. Thus... 

A gas mixture includes S02, S03 and 02. Partial pressures of these species are given in the following ... 

We will complete our discussion of chemical potential by using Equation IV. 17 to obtain the logarithmic term in concentration that is found for fij in a liquid phase. First, it should be pointed out that Equation IV. 17 has no concentration term per se for the chemical potential of species j in a gas phase. However, the partial pressure of a species in a gas phase is really analogous to the concentration of a species in a liquid e.g., PjV = rijRT for gaseous species/ (Eq. IV.15), and concentration means number/volume and equals n/V, which equals P/RT. 

Adsorption on a solid surface is the process of a species present in a gas or liquid phase adhering to the surface of the solid [46,104,105], This adsorption occurs due to molecular interactions between the adsorbing species and the solid. If adsorption is characterized by relatively weak interactions, such as those typical of van der Waals forces, the process is called physisorption. Because such weak forces occur between all molecules, physisorption is typically reversible and will occur at any surface when the normalized concentration of the adsorbing species is sufficiently high. For a gas-phase species, the normalized concentration is equal to pipa where p is the partial pressure of the species and po is its saturation vapor pressure. The endpoint for physisorption occurs when the concentration of the adsorbing species reaches its saturation value. For a gaseous contacting phase, condensation occurs at this point, (i.e., when p = po). 

If one wishes to calculate the mole fraction of air dissolved in the water, then Raoult s law caimot be applied, because the critical temperature of air is much lower than 298.15 K (25°C). This problem can be solved by Hemy s law, applied here for pressures low enough tliat the vapor phase may be assumed an ideal gas. For a species present as a very dilute solute in the hquid phase, Henry s law then states that the partial pressure of the species in the vapor phase is directly proportional to its liquid-phase mole fraction. Thus,... 

Calculate the equilibrium partial pressures of all species involved in a gas-phase chemical or gas-solid reaction from the initial pressure(s) of the reactants (Section 14.5, Problems 27-32). 

At high temperature, the molecules of dopant are dissociated into different volatile species. The equilibrium partial pressures of these species can be calculated thermodynamically. In the case of diborane, equilibrium partial pressures of gaseous species in the system Si-H-Cl-B have been calculated by Bloem and Giling [8]. The data can provide information on dominant dopant species for a given partial pressure. For example, for low partial pressure of PH3, the dominant species in the gas phase are PH3 and PH2. For high partial pressure PH3, P2 becomes the dominant species. 

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

For the closed system, there is no replenishment, whereas in the open system the partial pressures of all species in the gas phase are maintained constant at their initial values and aqueous-phase concentrations are determined by equilibrium. 

The equations above have been the basis of most atmospheric aqueous-phase chemistry models that include mass transport limitations [e.g., Pandis and Seinfeld (1989)]. These equations simply state that the partial pressure of a species in the cloud interstitial air changes due to mass transport to and from the cloud droplets (incorporating both gas and interfacial mass transport limitations). The aqueous-phase concentrations are changing also due to aqueous-phase reactions that may be limited by aqueous-phase diffusion included in the factor Q. 

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