Physical properties of {Fe2(SO4)3 + PEG 4000 + H2O} solutions at high temperatures

•Physical properties of the Fe2(SO4)3 + PEG 4000 + H2O system were measured.•The properties at 323.15, 333.15 and 343.15 K were correlated by the Othmer’s rule.•The isentropic compressibility and excess molar volumes were determined.•Lorentz-Lorenz approximation was applied to predict density and refractive index.•Good results were obtained by Othmer’s rule and Lorentz-Lorenz approximation.