1Department of Chemistry, Sharif University of Technology, P.O.Box 11365-9465, Tehran, I.R. IRAN
2Department of Chemistry, Isfahan University of Technology, Isfahan, I.R. IRAN
In this work, we consider each normal alkane as a hypothetical mixtureof methyland methylene groups, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) is extended for such a hypothetical mixture. Also, three basic compounds, namely, propane, n-butane and cyclohexane, are used to obtain the contribution of each carbonic group in the EOS parameters. Using the calculated EOS parameters along with the modified EOS, the density of n-alkanes and their mixtures at different pressures and temperatures are calculated. The average percentage error in density is found to be less than 1.5% for both the pure normal alkanes and their binary mixtures.