A CONTRIBUTION TO THE UNDERSTANDING OF THE EQUATION OF STATE OF GASES AT HIGH TEMPERATURE AND DENSITIES
NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD
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Intermolecular potential functions and certain means by which they can be obtained from experiment were studied as the first step in the evaluation and development of a high density equation of state. The second virial coefficient was found to be a poor method for reduced temperatures on the 12, 6 scale greater than 2.0 while transport coefficients were found to be poor in the range 1.5 T 12,6 5.0. Experimental second virial coefficient data was fitted to 40 intermolecular potential functions for each of 15 substances. That such data taken in the range T 12,6 2.0 cannot serve as a means for determining the potential function is clearly demonstrated. Also indicated is the result that such data in the range T 12,6 2.0 cannot be used for determining more than three potential parameters. The Percus-Yevick theory was investigated and appears to be as applicable to air as it is to argon. The theory was found to be sensitive to the choice of the intermolecular potential function. The effect improving the potential functions has on the NBS tables of equilibrium properties of gases at high temperatures was investigated and found to be generally small although changes of approximately 2 were obtained at the highest densities.