Orthobaric volumetric properties of liquid (propane plus cyclopropane) between T = (158 and 201) K

A recently described differential densimeter was used to measure the densit ies of Liquid mixtures of propane and cyclopropane at three different compo sitions, and several temperatures between T = 158 K and T = 201 K. The dens imeter cell was calibrated with propane and ethane at T = 121.902 K. The differences in density between pure propane and pure cyclopropane were measured along the saturation line between T = 152 K and T = 176 K with an estimated precision of +/- 0.1% per cent. The liquid cyclopropane density w as obtained, relative to the propane literature density data, in the same t emperature range and with an estimated precision of +/- 0.02 per cent. The differences in liquid density between pure propane and three mixtures o f propane and cyclopropane were measured between T = 158 K and T = 201 K. T he compositions studied had the following approximate propane mole fraction s: 0.3, 0.5, and 0.8, respectively. The excess molar volumes calculated fro m the experimental data decrease with temperature, and a maximum value of V -m(E) = 0.18 cm(3) mol(-1) is found for the mixture with x(C3H8) = 0.5 at T = 159 K. The estimated precision in the excess molar volumes is +/- 0.02 c m(3) mol(-l). The results for the excess molar volume are compared with the predictions o f the Deiters equation of state. (C) 1999 Academic Press.