Calculating critical exponents of the phase-equilibrium curve for liquid-vapor aqueous solutions of aliphatic alcohols

Abstract

Based on previously obtained experimental data corresponding to the points of liquid-vapor phase transformations in aqueous solutions of aliphatic alcohols (methanol, ethanol, n-propanol), we plot the temperature dependence of the density of liquid and vapor phases along the curve of their coexistence and in the critical region. It is established that the power functions $\rho _{1,v} = \rho _c (1 \pm B_0 \tau ^{\beta _0 } + B_1 \tau ^{\beta _1 } \pm B_2 \tau ^{\beta _2 } )$ and $(\rho _1 - \rho _v )/2\rho _c = B_0 \tau ^{\beta _0 } + B_2 \tau ^{\beta _2 }$ adequately describe the dependence of the lower density of solutions ω = (ρ_l,p − ρ_c)/ρ_c on reduced temperature τ = (T _c − T)/T _c, the alcohol concentration, and the number of carbon atoms (in a molecule of alcohol) in the two-phase region and in the vicinity of the critical point at critical index β₀ = 0.365 ± 0.002 and B ₀ = (2.471–2.803) ± 0.005.