DIRECT VAPOR-PRESSURE MEASUREMENTS OF 10 N-ALKANES IN THE C-10-C(28) RANGE

Direct vapor pressure measurements of zone-refined n-alkane samples (decane, 323-588 K; dodecane, 352-588 K; tetradecane, 373-588 K; hexadecane, 393-583 K; octadecane, 413-588 K; nonadecane, 423-588 K; eicosane, 433588 K; docosane, 453-573 K; tetracosane, 453-588 K; and octacosane, 483-588 K) are reported. Most temperature measurements are accurate within +/-0.02 K with a maximum uncertainty estimated at DELTAT(exp) = +/-0.03 K. The maximum uncertainty of the pressure measurements, which range from 0.082 to 1385 kPa, depends on the measured pressure according to DELTAP(exp) = 0.0015P + 0.0048. The vapor pressures are fitted to a ''2.5-5'' Wagner equation and shown to be of high precision. The fits are used to make comparisons with selected literature results. Additional fits are presented which combine literature vapor pressures with the new data. These are based on the two-real fluid Corresponding States Principle (CSP) method used by Ambrose and Patel (Ambrose, D, and Patel, N.C., 1984. J. Chem. Thermodyn., 16: 459-468), which has been applied to extrapolate and smooth vapor pressures. Morgan (Morgan, D.L. and Kobayashi, R., 1994. Extension of Pitzer CSP models for vapor pressures and heats of vaporization to long-chain hydrocarbons. Fluid Phase Equilibria, 94: 51-87.) has incorporated the experimental measurements into Pitzer-type CSP correlations.