Measurement and Correlation of Some Interaction Second Virial Coefficients from − 125° to 50°C. I

Interaction second virial coefficients have been measured from − 125° to 50°C in 25° increments for the following systems: N₂–Ar, Ar–H₂, Ar–He, Ne–Ar, N₂–H₂, N₂–He, Ne–N₂, H₂–He, Ne–H₂, and Ne–He. The excess second virial coefficients were reproduced usually within 0.1 cc/mole by measuring the pressure change of mixing two pure gases at constant temperature and volume. With these excess quantities and literature values of $B_{11}$ , the interaction second virial coefficients were calculated. The comparison between experimental interaction second virial coefficients and those calculated by the Kihara potential was considered good at the higher temperatures and fair to poor at the lower temperatures where the deviation was sometimes as much as 8 cc/mole. This deviation is probably mainly due to the assumption of the geometric‐mean mixing rule for the characteristic energy between the dissimilar molecules. In the temperature range of − 125°–50°C, the excess quantity $E$ was empirically correlated to the absolute temperature by the relation, ${\mathrm{E\hspace{0.17em}=\hspace{0.17em}\alpha T}}^{\beta }$ where the value of $\beta$ was essentially the same for most of the binary mixtures studied.