Experimental research of thermodynamic properties of water + aliphatic alcohol mixtures in the wide range of parameters of state

Experimental data of p, r, T, x - relations for water+aliphatic alcohol binary systems (methanol, ethanol, n-propanol) for values of composition x (0.2, 0.5, 0.8 mole fraction of alcohol) among the phase equilibrium line in one phase (liquid, vapor) and in supercritical regions are described by polynomial polynomial equation of state, represented by expansion of the compressibility factor Z = p/RTρ into a power series of density and temperature: $Z=\frac{p}{RT{\rho }_m}=1+{\sum }_{i=1}^m{\sum }_{j=0}^n{\sum }_{k=0}^s{a}_{ijk}{\omega }^i{x}^k/{\tau }^j$, and $p=RT{\rho }_m=[1+{\sum }_{i=1}^m{\sum }_{j=0}^n{\sum }_{k=0}^s{a}_{ijk}{\omega }^i{x}^k/{\tau }^j]$, where ω = ρ/ρ_c and temperature τ = T/T_c – is reduced density and reduced temperature; ρ_c, T_c – critical density and critical temperature; R = 8.314 J/(mol⋅K) is the universal (molar) gas constant.

The average relative deviation of calculated values of pressure from experimental ones is 1.1%. By using this equation and expressions thermodynamic properties: coefficient of isothermal compressibility K_T, coefficient of volume thermal expansion, pressure coefficient, internal pressure p_i, isochoric heat capacity C_v, isobaric heat capacity C_p, speed of sound, adiabatic index k, Helmholtz free energy F, Gibbs energy G, entropy S, enthalpy H, internal energy U, differential isothermal throttling effect d^is, differential adiabatic throttling effect d^ad. (paper)