Hidrokarbon sıvıların istatistiki termodinamiği: ultrasonik ses hızının termodinamik niceliklerle ilişkilendirilmesi

Abstract

The estimation of the speed of sound in dense chain molecules is an important subject both from the point of their physical specifications and the interrelation of their thermodynamic quantities. In our treatise the cell model of Lennard-Jones and Devonshire generalized to assemblies of chain molecules due to Prigogine et al. is employed. Simha and Somcynsky (SS) made an arrangement in the model increasing the disorder by introducing the holes in quasi-lattice. Established equation of state was intensively applied to low and high molar mass fluids. Our present interest is to estimate the speed of sound using the latter including other possible degrees of freedom (vibrational, translational and rotational, etc.) into Helmholtz energy for the calculation of the heat capacity of the system. Estimating the speed of sound necessitates the calculation of isentropic compressibility, thermal expansion and heat capacity. The deviation in the outcome is in a good agreement at high pressure for the thermophysical properties and the speed of sound, but at low pressure the errors are apparently high, say %6 maximum deviation observed in the speed of sound for tridecane. The results are promising and promoting for future study.