Saturated liquid densities of n-butane-isobutane, n-butane-propane, isobutane-propane, and n-butane-isobutane-propane mixtures

In a study on the saturated liquid densities of LPGs, the liquid densities of n-butane-isobutane, n-butane-propane, isobutane-propane, and n-butane-isobutane-propane mixtures were measured at 273.15-323.15 K using a pressurized pycnometer, the maximum error of estimation being 0.2%. With the exception of n-butane-isobutane mixtures, the experimentally determined densities were higher than the densities calculated additively from the mole fractions, but were almost the same as the densities calculated additively from the weight fractions, within the bounds of experimental error. Hankinson and Thomson's and Teja's methods gave estimates of almost equal precision with an absolute average error of < 0.1%, but the MRK equation gave rather less precise estimates.