Abstract
Most binary vapor–liquid data are reported as P–x–y data sets. Barker’s method, the conventional procedure for extracting the adjustable parameters of an activity coefficient model, utilizes just the P–x data component. An alternative but analogous procedure relies on experimental y–x information and is based on the dimensionless group Ψ = αP2*/P1*. In this approach data points at the composition limits are more heavily weighed than those in the mid-range. It is found that Ψ = Ψ(x1) is nearly temperature invariant for non-ideal systems that contain an associating component. This suggests the utility of temperature-independent model parameters and facilitates their estimation.
