Ethylene second virial coefficients

The effects of systematic errors are best studied by analyses of accurate Burnett data with superimposed simulated errors. For a relative pressure offset of 0.003%, which is comparable with the accuracy of piston gauges, the ethylene second virial coefficient of —167 cm3/mol changes only by 0.02 cm3/mol. Thus, this type of error is largely cancelled in the Burnett method. An offset in N of 11 ppm, which is comparable with the N variation we expect, changes the same second virial coefficient by 0.1 cm3/mol. Errors resulting from truncation of the series... 

In Figure 5, we present a comparison of our preferred values for the ethylene second virial coefficient with comparable state of the art results obtained by Douslin and Harrison (2). The experimental method and data analysis used by Douslin are independent from ours. In Douslin s experiment, all of the variables required for the calculation of the compressibility factor are measured, whereas in the Burnett method only two variables are measured. Aslo, in this experiment the same sample of gas is retained for the entire experiment in the Burnett isothermal method, the sample is changed for each sequence of measurements. Furthermore,... 

Figure 5. Ethylene second virial coefficient comparison. AB2=B2 (Dous-lin) — B2 (this chapter) (%), Douslins graphical value (O), least-squares value from Douslins data.

State-of-the-Art Determination of the Second Virial Coefficient of Ethylene for Temperatures from 0° to 175 °C... 

Values of the second virial coefficient of ethylene for temperatures between 0° and 175°C have been determined to an estimated accuracy of 0.2 cm3/mol or less from low-pressure Burnett PVT measurements. Our values, from —167 to —52 cm3/mol, agree within an average of 0.2 cm3/mol with those recently obtained by Douslin and Harrison from a distinctly different experiment. This close agreement reflects the current state of the art for the determination of second virial coefficient values. The data and error analysis of the Burnett method are discussed. 

A container with a volume of V = 0.1 is filled with m = 10 kg ethylene at a temperature of T = 300 K. What will be the pressure and compressibility factor of the gas. Use the virial equation truncated after the second virial coefficient and the Peng-Robinson equation of state to describe the PVT-behavior. (virial coefficient B = -138 cm /mol, all other properties are given in Appendix A). 

As the core of an ethylene molecule C2H4 we choose a thin rod connecting two carbon atoms with length I = 1.33 A. The choice of a rod core may be reasonable because of the it electrons and because of the fact that each molecule in an ethylene crystal can rotate about the CC bond. The values of po nd Uq determined from the second virial coefficient are... 

Second virial coefficient of poly(butylene oxide-b-ethylene oxide-b-butylene oxide)... 

Table 1. Second virial coefficient of poly(dimethylsiloxane-b-ethylene oxide).

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