Second virial coefficients of tetrachloromethane from measurements of the excess molar enthalpy ofyN2+ (1−y)CCl4over the temperature range 333.2 K to 413.2 K

Benzene–polar fluid association. An analysis of measurements of the vapour phase excess molar enthalpy of mixtures of (cyclohexane, or benzene + polar and non-polar fluids)

“…The value 1.175 for (cyclohexane + dimethyl ketone) is significantly higher than the figure 1.074 given by equation (30). To see if this was due to the choice of potential parameters for dimethyl ketone we repeated the analysis of the (cyclohexane + dimethyl ketone) H E m measurements using the Stockmayer parameters for acetone ε/k = 380 K, σ = 0.3768 nm, and t * = 1.045 which were determined from Joule-Thomson coefficients.…”

“…It was thought that the apparently low value of 0.88 could be due to the choice of potential parameters for chloromethane, but on investigation no parameters which were consistent with the value 1.013 could be found. We note that the value of (1 − k 12 ) which fit the H E m measurements for the two ketones are greater than the values calculated from equation (30), whereas for the three chloromethanes they are smaller. This might be a consequence of repulsive forces due to the chlorine atoms.…”

“…Before beginning measurements on tetrachloromethane mixtures it was once again necessary to precede the work by measurements on (nitrogen + tetrachloromethane) (30) to improve the quality of the available second virial coefficients. The values of B obtained from these H E m measurements are less negative by about 20 cm 3 · mol −1 than the bulk of the literature values.…”

“…The H E m measurements on (tetrachloromethane + cyclohexane or benzene) (30) were a surprise. First of all, for both mixtures the values of H E m were all between ±2 J · mol −1 , and to make the measurements it was necessary to increase the sensitivity of the apparatus, improve the stability, and be exceedingly painstaking and patient.…”

“…To do this it was necessary to assume a combining rule for the well depth ε 12 , but so long as the gas imperfection of the fluid under investigation was large so that the cross term second virial coefficient was small, this assumption was reasonable. This method was used to obtain second virial coefficients for benzene, (13) cyclohexane, (13) dimethyl ketone, (25) diethyl ketone, (26) dioxane, (27) dichloromethane, (28) chloroform, (29) tetrachloromethane, (30) water, (31) methanol, (32) and ethanol. (33) where…”