TEMPERATURE-DEPENDENCE OF THE SURFACE-TENSION FOR BINARY-MIXTURES OF N-BUTANENITRILE PLUS N-ALKANES

The differential capillary-rise method was used to determine the ortho baric surface tension of binary liquid mixtures of n-butanenitrile mix ed with n-pentane, n-hexane, and n-heptane, throughout the composition range, at 293.15, 303.15, 313.15, 323.15, 333.15, and 343.15 K. Furth ermore, the system with n-hexane was also studied at 263.15 K, i.e., 1 9 K above its upper critical solution temperature, over the whole comp osition range. For each binary system the surface tension changes regu larly with both temperature and composition between the values of the pure components. The results are discussed in terms of deviations from surface ideality and related to the large positive deviations observe d for bulk properties of the same systems.