Phase transitions and critical properties of $\rm C_3\rm H_7\rm OH$–$\rm C_5\rm H_{12}$ system

Using experimental data on the $(p{,}~T{,}~x)$ and $(p{,}~\rho{,}~T{,}~x)$ dependences of mixtures of $1$-propanol with $0.2{,}~0.5{,}~0.8$, and $0.9$ mole fractions of $n$-pentane in the two-phase (liquid–vapor) and single-phase (liquid and vapor) near-critical and supercritical regions, we determined the parameters of the points of the liquid–vapor phase transitions by the kink in the isochores $p = f(T)_{\rho{,}x}$ and the critical point parameters by the semigraphical method, taking the scaling behavior into consideration. The dependence of pressure on temperature, density, and composition along the phase coexistence curve is described by a three-parameter polynomial equation of state, which is the expansion of the compressibility factor $Z = p/(RT\rho)$ into series in powers of reduced density, reduced temperature, and composition. The average relative error of the deviations of the calculated pressure values from the experimental ones does not exceed $1\%$. The temperature dependence of the system density along the liquid–vapor coexistence curve is described by two power functions at the critical exponent $\beta_0 = 0.338 \pm 0.002$: far from the critical point and in the symmetrical part of the equilibrium curve. The average relative error was $1.41\%$.