Abstract
The thermodynamic tables of ethylene and water were revised in the critical region by using a new isochoric equation of state. The new tables are consistent with the Hall-Eubank formulation and are compatible with recent experimental measurements. It was found that these two chemically dissimilar substances have almost equal critical exponents: [beta] = 0.350 ± 0.006, [theta] = 0.23 ± 0.02, [lamda] = 0.52 ± 0.02, [alpha*] = 0.125 ± 0.005. These values are very close to the exponents determined for other substances. The method is thus a powerful technique for correlation of the thermodynamic properties of any substance in the critical region. A new isochoric equation of state (EOS) was perfected for the single-phase region near the critical point (CP). Starting at the vapor-liquid coexistence curve, the EOS has an initial slope consistent with (1) the power-law behavior for the difference of isochoric slopes issuing from the same point on the vapor pressure curve and (2) the rectilinear behavior of their sum. The initial curvature of the EOS was found to be a sinusoidal function of density with a curvature near zero at the critical isochore. The two-phase isochoric heat capacity was found to diverge with the exponent [alpha*] = 0.125 ± 0.005 along the rectilinear diameter line. The C[subscript]v isotherms in the two-phase region resulted in straight line with slopes which were in good agreement with the value derived from the vapor pressure equation. Single-phase heat capacities were insensitive to density and divergence was not substantiated, either by the new equation of state or by the C[subscript]y data (the latter had too much scatter to allow a meaningful conclusion). Thermodynamic property tables for density, internal energy, enthalpy, entropy, Gibbs function and isochoric heat capacity as functions of pressure and temperature were generated in the critical region for both ethylene and water...
Nehzat, Mohammad Sadegh (1978). Thermodynamic properties of ethylene and water in the critical region. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -324090.