The entropies of n-heptane, n-octane, n-nonane, and n-undecane over a wide range of the liquid and gaseous states

The entropies S of C7-C11 normal alkanes over the temperature and pressure ranges 300-620 K and 0.5-60 MPa were obtained by the integration of the experimental isobars of isobaric heat capacity C p . The C p data were obtained using a flow adiabatic calorimeter with calorimetric flow rate measurements. The entropy values were determined up to critical temperatures by extrapolation from the sides of liquid S and gas S phases. The p-T-S thermodynamic surfaces of the alkanes under consideration in the liquid and gas phases were constructed. A generalized temperature dependence of S and S was determined for the homologous series over the temperature range from the triple to critical point within the framework of similarity theory. © 2008 MAIK Nauka.