SURFACE-TENSION OF NITRIC-OXIDE AND ITS BINARY-MIXTURES WITH KRYPTON,METHANE, AND ETHENE

The surface tension of three binary liquid mixtures of NO with Kr, CH4 , and C2H4 has been determined as a function of composition in the tem perature range 102.0 to 119.0 K. These measurements are a contribution to the study of binary liquid mixtures in which one component is unas sociated while the molecules of the other can associate between themse lves. Nitric oxide is the simplest molecule capable of forming dimers, but not larger aggregates. This results in the surface tension of liq uid nitric oxide having a strong temperature dependence: when the temp erature increases the degree of dimerization decreases, contributing t o a larger decrease of the surface tension, The surface tension of NO mixtures shows strong deviations from ideality. The mixtures containin g Kr and CH4 exhibit negative deviations, while for the NO + C2H4 syst em the surface tension shows a complex dependence on the composition, This strong departure from ideality had already been found for the bul k properties of these three systems, The surface tension of the CH4 Kr system, already well characterized in the literature, was also meas ured to test our equipment. (C) 1997 Academic Press.