Complexity of Density Dependencies of Thermal- and Internal- Pressure Compared to that of Total Pressure

A simple equation of state (EoS) was recently been introduced [۱]as (…)or(…)where is the compressibility factor,and are thermal and internal contributions to compressibility factor, is molar volume, and , , and are temperature dependent parameters. This EoS has been found to be accurate for all types of nano- and bulk- solids, an ionic liquid model, confined water in the carbon nanotubes with different diameters [۲], and bulk fluids, in the entire temperature and pressure ranges for which experimental data are reported, except for the isotherms within the critical region. The aim of this work is to investigate the validity of a ۳-term expression similar to eq ۱ for both thermal and internal contributions tothe compressibility factor, separately.