The Interaction Coefficients of Gas Mixtures¹

Abstract

The method of Edwards and Roseveare has been used to study the interaction coefficients of the following gaseous mixtures at 30°: COr-Ni, Or-Ní, CO2-O2. _ An apparatus of improved design is described for making the measurements. The results give proof that the method is satisfactory for evaluation of the quantity [2Ba -(Bu + ¿22)], where 512 is the interaction coefficient and Bu and Ba are the individual second virial coefficients of the constituents of the mixture. Values of the interaction coefficients determined in this way for the CO2-N2 and O2-N2 systems agree satisfactorily with theoretical values based on simple combination rules for the force constants involved. The CO2-O2 results show a disagreement with the theoretical values which may be due to these combination rules.

Ab initio intermolecular potential energy surface for the CO2—N2 system and related thermophysical properties

“…We note that we have reanalyzed the measurements of Martin et al 46 using the more accurate values provided by Hellmann 5,6 for the pure-component virial coefficients, leading to excellent agreement. Several other data sets 39,40,47,50 agree within our stated uncertainty. However, the few available experimental data below ambient temperature often lie significantly outside our uncertainty interval, in particular, the data of Brewer, 43 of Ng, 44 and, at very low temperatures, of Yakimenko et al 45 At ambient and higher temperatures, the data of Cottrell et al 41 and the datum of Edwards and Roseveare 38 deviate quite strongly not only from our calculated values but from the consensus of other experimental data as well.…”

“…To account for quantum effects, the intermolecular pair potential V in Eq. 7was replaced by the quadratic Feynman-Hibbs data sets 39,40,47,50 obtained by experimentalists with a well-established reputation agree within our stated uncertainty. However, the few available experimental data below ambient temperature often lie significantly outside our uncertainty interval, in particular, the data of Brewer, 43 of Ng, 44 and, at very low temperatures, of Yakimenko et al 45 At ambient and higher temperatures, the data of Cottrell et al 41 and the datum of Edwards The transport properties of a dilute gas mixture can be determined using the kinetic theory of molecular gases.…”

“…The precision of the final results is better than 0.004 cm 3 /mol at all temperatures. Figure 4 shows the results for the cross second virial coefficient compared with experimental data from the literature [38][39][40][41][42][43][44][45][46][47][48][49][50] and with the correlation of Dymond et al 51 The figure also displays our estimate of the combined standard uncertainty (i.e., coverage factor k = 1). We based this estimate on the difference in the values for the cross second virial coefficient resulting from using the proposed PES and a PES that we fitted to the interaction energies resulting from the highest computed levels of theory, but without extrapolation of the two correlation energy contributions to the CBS limit.…”

“…Below 300 K, the number of trajectories was gradually reduced down to 800 000 at 60 K because of the increasing computational cost of calculating trajectories with the desired accuracy at lower energies. A weighted integration over the total energy yielded temperature-dependent generalized cross sections in the center-of-mass frame at temperatures from 150 K 12, , of experimental data, [38][39][40][41][42][43][44][45][46][47][48][49][50] the correlation of Dymond et al, 51 and results from the classical statistical treatment (B cl 12 ) for the CO2-N2 cross second virial coefficient from values obtained with Eq. (10).…”

Die zweiten Virialkoeffizienten der Systeme N2–O2und N2–NO von 87 K bzw. 124 K bis 475 K

“…Dunlop[24] bei 290, 300 und 320 K, dem MeBpunkt von Miller[25] bei 303 K und den Tieftemperaturdaten von Friedman[26] keine Virialkoeffizienten vor, obwohl diese Mischung den Hauptanteil der Luft ausmacht. Als Startwert fur unsere Temperaturabhiingigkeits-Messungen benotigen wir den Wertdes Virialkoeffizienten bei Zimmertemperatur.…”