# Redlich-Kwong Equation of State

Written by Jerry Ratzlaff on . Posted in Thermodynamics

Redlich-Kwong equation of state derives from the Van der Waals equation and generally more accurate.  It is not used as much becaused the overall difficulty to use.

## Redlich-Kwong Equation of State Formula

 $$\large{ p = \frac{R \; T}{ V_m \;-\; b } - \frac{ a }{ \sqrt{T} \; V_m \; \left( V_m \;+\; b \right)' } }$$

### Where:

 Units English Metric $$\large{ p }$$ = pressure of gas $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$\large{ a }$$ = correction for the intermolecular forces $$\large{dimensionless}$$ $$\large{ b }$$ = adjusts for the volume occupied by the gas particles $$\large{in^3}$$ $$\large{mm^3}$$ $$\large{ V_m }$$ = molar volume of gas $$\left( \frac{V}{n} \right)$$ $$\large{\frac{ft^3}{mol}}$$ $$\large{\frac{m^3}{mol}}$$ $$\large{ n }$$ = number of moles of gas $$\large{dimensionless}$$ $$\large{ R }$$ = specific gas constant (gas constant) $$\large{\frac{lbf-ft}{lbm-R}}$$ $$\large{\frac{J}{kg-K}}$$ $$\large{ T }$$ = temperature of gas $$\large{R}$$ $$\large{K}$$