Density, Speed of Sound, Compressibility, and Excess Properties of Carbon Dioxide plus n-Dodecane Binary Mixtures from 10 to 70 MPa

Density and speed of sound of carbon dioxide + n-dodecane binary mixtures were measured at pressures from 10 to 70 MPa and at two temperatures around the critical temperature of carbon dioxide (303 and 313 K). The measurements were carried out in pure n-dodecane and five different mixtures with CO2 molar percentage ranging from 20 to 85%. A vibrating U-tube densimeter was used to measure density, whereas speed of sound measurements were carried out by a pulse-echo technique using a double path length sensor working at 3 MHz. Isothermal and isentropic compressibilities were determined from both measurements. Finally, excess volume, excess isothermal compressibility as well as excess speed of sound and excess isentropic compressibility were estimated in the same p,T range and represented as a function of CO2 content.