Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The (p,p, T,x) properties for {x propane + (1 - x) isobutane} with x = (1.0000,0.2765,0.5052, and 0.7468) in the compressed liquid phase were measured by means of a metal-bellows variable volumometer in the temperature range from (280 to 440) K at pressures from (1 to 200) MPa. The mole fraction purities of the propane and isobutane used in the measurements were 0.9999 and 0.9999, respectively. The expanded uncertainties (k = 2) in temperature, pressure, density, and composition measurements have been estimated to be less than +-3 mK; 1.4 kPa (p (7 MPa), 0.06% (7 MPa less thanp (50 MPa), 0.1% (50 MPa less thanp ( 150 MPa), and 0.2% (pgreater than 150 MPa); 0.09%; and 1.3* 10-4 , respectively. In the region above 100 MPa at T (280 and 440) K, the uncertainty in density measurements increases from 0.09% to 0.13% and 0.22%, respectively. Comparisons of the available equation of state with the present measurements are reported. On the basis of the present results, the excess molar volume V:;' of the mixtures was calculated and illustrated as a function of temperature and pressure.