QUASI-ISOCHORIC P-P-T-MEASUREMENTS AND 2ND VIRIAL-COEFFICIENT OF N-HEPTANE

Quasi-isochoric p rho T measurements on n-heptane vapor were carried o ut in the low density region using an improved apparatus that was orig inally proposed by Opel and Schaffenger (Wiss. Z. Univ. Rostock N18:87 1, 1969). The experimental results extend over the temperature range b etween 350 and 600 K and the density range between 11.5 and 52.2 mol m (-3). Above 473 K a small but significant influence of decomposition w as found. Accordingly, a correction scheme assuming a trace of decompo sition products was applied to these data. Second virial coefficients were derived with an assumed maximum uncertainty of +/-3%. The results are compared with others in the literature and used to develop an imp roved correlation function for the temperature dependence of B(T).