The second virial coefficient of carbon dioxide

Abstract

In an earlier paper some determinations of the virial coefficients of carbon dioxide and ethylene, planned as part of a continuing investigation of the (p,v,t) properties of gases and gaseous mixtures, were described. These measurements utilized the `series-expansion' technique which it was intended to use consistently throughout the series. In view, however, of the aims of the work and the consequent demands on accuracy, it was decided, as a precaution against the possible intrusion of undetected systematic error, to carry out a limited series of measurements on one gas - carbon dioxide - by an independent method. For this the `piezometer' technique developed by Michels and his collaborators was chosen. This paper compares the values of the second virial coefficients obtained over the temperature range -10 to 200?C in the two series. These proved to be in very precise agreement, the discrepancies at corresponding temperatures being nowhere greater than 0.03 ? 10-3 amagat (0 7 cm3 mole-1) and on the average of the order of only 0 01 ? 10-3 amagat (0.2 cm3 mole-1). The significance of these results is discussed.