Analytical Representation of the Curves of Liquid–Vapor Phase Equilibrium for Saturated Hydrocarbons

A unified two-parameter approximation formula is used to derive analytical dependences for $P(T)$ curves of liquid-vapor phase equilibrium of saturated hydrocarbons $\text{C}_n\text{H}_{2n + 2}$ (alkanes) with numbers $1 \le n \le 20$ from methane $(n = 1)$ to eicosane $(n = 20)$. Two approximation options are given, namely, that involving the use of individual values of parameters for each alkane, and that in the form of a unified formula in which the only parameter characterizing an individual component is the number $n$.