Equation of state of gases at low temperatures. Part 1.—Second virial coefficient of argon and krypton

Abstract

An apparatus of the Burnett type has been built with which to measure accurately the second virial coefficients of gases at low temperatures. The principal feature is a mercury manometer with which pressures up to 1 bar can be measured with an accuracy of 2 × 10^–6 bar. The second virial coefficients B of argon (80–190°K) and of krypton (110-225°K) have been measured with absolute accuracies of from 0.001 to 0.01 m³ kmol^–1, and are discussed in relation to the pair potential of the intermolecular forces. The rapid fall of B at low temperatures implies, in each case, a deeper well in the potential than has been proposed heretofore.