A Ghotbi - Department of Chemistry, Payme Noor University, Urmia, Iran
S.A Razavizadeh - Department of Chemistry, Payme Noor University, Shiraz, Iran
M Azadpour - Department of Chemistry, Payme Noor University, Shiraz, Iran

Equation of state (EoS) is a thermodynamic equation, which explains state of substances indifferent physical condition. Equation establishes relation between two or more variablessuch as density, volume, temperature and pressure and describes the properties of fluids,solids and mixtures. Redlich–Kwong equation of state is a two parameters cubic equation,which predicts the thermophysical properties of fluids. [1, 2].