Second virial coefficient for real gases at high temperature

Abstract

We study the second virial coefficient, $B(T)$, for simple real gases at high temperature. Theoretical arguments imply that there exists a certain temperature, $T_i$, for each gas, for which this coefficient is a maximum. However, the experimental data clearly exhibits this maximum only for the Helium gas. We argue that this is so because few experimental data are known in the region where these maxima should appear for other gases. We make different assumptions to estimate $T_i$. First, we adopt an empirical formulae for $B(T)$. Secondly, we assume that the intermolecular potential is the Lennard-Jones one and later we interpolate the known experimental data of $B(T)$ for Ar, He, Kr, H_2, N_2, O_2, Ne and Xe with simple polynomials of arbitrary powers, combined or not with exponentials. With these assumptions we estimate the values of $T_i$ for these gases and compare them.