Benedict, Webb and Rubin equation of state

The Benedict, Webb and Rubin equation of state is an empirical equation of state, based on the Beattie-Bridgeman equation of state, which has the following functional form (Eq. A10 of ):

$P=RT\rho +\left(B_{0}RT-A_{0}-{\frac {C_{0}}{T^{2}}}\right)\rho ^{2}+(bRT-a)\rho ^{3}+a\alpha \rho ^{6}+{\frac {c\rho ^{3}(1+\gamma \rho ^{2})\exp(-\gamma \rho ^{2})}{T^{2}}}$

where $P$ is the pressure, $T$ is the temperature, $\rho$ is the density, and $R$ is the molar gas constant. $B_{0}$, $A_{0}$, $C_{0}$, $b$, $a$, $c$, $\gamma$ and $\alpha$ are adjustable parameters.

References

Related reading

• Manson Benedict, George B. Webb, and Louis C. Rubin "An Empirical Equation for Thermodynamic Properties of Light Hydrocarbons and Their Mixtures II. Mixtures of Methane, Ethane, Propane, and n-Butane", Journal of Chemical Physics 10 pp. 747-758 (1942)
• Giorgio S. Soave "An effective modification of the Benedict–Webb–Rubin equation of state",Fluid Phase Equilibria 164 pp. 157-172 (1999)