Gas mole fraction

The vapor pressure of a volatile liquid determines the maximum mole fraction of that substance in a gas phase in contact with that volatile liquid. Remember that with gases, mole fraction is the same as volume fraction and pressure fraction. This is the principle that guides an anesthetic vaporizer (Figure 7.34). 

So iar in our energy calculations, we have been considering each substance to be a completely pure and separate material. The physical properties of an ideal solution or mixture may be computed from the sum of the properties in question for the individual components. For gases, mole fractions can be used as weighting values, or, alternatively, each component can be considered to be independent of the others. In most instances so far in this book we have used the latter procedure. Using the former technique, as we did in a few instances, we could write down, for the heat capacity of an ideal mixture,... 

For ideal gases, mole fraction is the same as volume fraction. From Table 17.1 of the text, CO2 is 0.033% of the composition of dry air, by volume. The value 0.033% means 0.033 volumes (or moles, in this case) out of 100 or... 

Fig. 14. Coiielation of effective average slope m of equilibrium line (dilute part of absorber) equilibrium line concave upward. gas mole fraction at...

Table III gives values of the changes in Gibbs energy, enthalpy, entropy, and heat capacity of the solution process as calculated from the equations of Table I. Figure 1 shows the recommended noble gas mole fraction solubilities at unit gas partial pressure (atm) as a function of temperature. The temperature of minimum solubility is marked.

Component Composition, separator gas, mole fraction Composition, stock-tank gas, mole fraction Composition, stock-tank liquid, mole fraction... 

Component Composition, separator gas, mole fraction lb mole j SP gas 1b mole j SP gas Composition, stock-tank gas, mole fraction lb mole j ST gas lb mole j ST gas Composition, stock-tank oil mole fraction lb mole j STO lb mole j res gas Composition, recombined gas, mole fraction lb mole j res gas... 

Component Separator gas, mole fraction lb mole i SP gas lb mole SP gas yi lb mole i SP gas lb mole SP liq 50.99y, Separator liquid, mole fraction lb mole i SP lia lb mole SP liq Xi lb mole j in well stream lb mole SP liq Xj+50.99yj Recombined gas, mole fraction lb mole j in well stream lb mole well stream Zj... 

The units of mole fraction are pound moles of component j per pound mole of gas. Mole fraction can be converted into gal/Mscf as follows. 

Component Composition of mixture, mole fraction zl Vapor pressure at 150°F, P i Composition of gas, mole fraction yi=zjf1 +ndp/t>v -1) Composition of liquid, mole fraction xi=yi(p/pvj)... 

Species Number of Moles per Second Gas Mole Fraction, y ... 

The unknowns in this equation are L u, G u, and x. The limiting operating line is that which just touches the equilibrium line at the conditions corresponding to the bottom of the tower. From Fig. 11.4, Xi is determined to be 0.177 from the equilibrium curve at Vi = 0.30. Equation (11.29) is then solved for and the values for the liquid and gas mole fractions are entered to give... 

If the system comes to equilibrium at 3000 K and 1 atm, the product gas mole fractions satisfy the... 

The second mechanism, called exchange or partial trapping describes the process of bubble transfer caused by larger bubbles, 50-500 (xm in diameter, that do not collapse but exchange gases across the bubble-water interface and then rejoin the atmosphere. In this case the flux depends on a different empirical constant. Vex (mol m d atm ), the atmospheric gas mole fraction, X, and the degree of overpressure of the gas in the bubble, W, caused by hydrostatic pressure and surface tension compared with the atmospheric pressure, P. The entire bubble flux can now be written as... 

Determination of gas pressures in expired air or blood depends on the application of certain physical principles (Table 27-4). The partial pressure of a gas dissolved in blood is by definition equal to the partial pressure of the gas in an imaginary ideal gas phase in equilibrium with the blood. At equilibrium, the partial pressure (tension) of a gas is the same in erythrocytes and plasma, so that the partial pressure of a gas is the same in whole blood and plasma. The partial pressure of a gas in a gas mixture is defined as the substance fraction of gas (mole fraction) times the total pressure. The tension of a gas in a liquid is, in fact, a measure of the chemical activity of the gas in the liquid. In the physicochemical literature, it is called the fugacity. 

Of course, it is not usually known what type of average to use, but for the present purpose, the precise value is not important. The integral can be thought of as the total change in gas mole fraction divided by the average driving force. 

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