Boynton and Bramley equation of state

The Boynton and Bramley equation of state is given by

$(p+\frac{a}{v^2})(v-b)=\frac{RT}{(1+\frac{{\psi }^2}{T^2})}$

where $\psi$ is a characteristic temperature. and where:

• $p$ is the pressure,
• $v$ is the volume,
• $T$ is the absolute temperature,
• $R$ is the molar gas constant; $R=N_A{k}_B$, with $N_A$ being the Avogadro constant and $k_B$ being the Boltzmann constant.
• $a$ and $b$ are constants that introduce the effects of attraction and volume respectively and depend on the substance in question.

For this equation at the critical point one has

$\frac{R{T}_c}{p_c{v}_c}=\frac{8}{3}(1+\frac{{\psi }^2}{T_c^2})$