Experimental and VTPR-predicted volumetric properties of branched hexanes

Densities of the four branched isomeric hexanes: 2,2,-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane and 3-methylpentane have been measured using a high-pressure, high-temperature vibrating tube densimeter system over a temperature range from 283.15 to 328.15 K and a pressure range from 0.1 to 65.0 MPa. The experimental densities have been satisfactorily correlated with the temperature and pressure using the Tait equation. Furthermore, using this equation and thermodynamic relations, isobaric expansibilities and isothermal compressibilities have been calculated. Finally, the volume translated Peng–Robinson group contribution equation of state (VTPR model) has been used to predict the densities of the compounds studied in the whole temperature and pressure ranges, the deviations between experimental and calculated densities in terms of relative root-mean square deviations are comprised between 0.40 and 0.55% for the liquids studied, so the predictions can be considered as satisfactory.