Thermodynamic activation functions of viscous flow of non-polar liquids

The thermodynamic activation function of viscous flow may be determined from the expression for the pre-exponential factor in the Eyring relationship (the viscosity coefficient), which is a function of density and relative permittivity, together with the thermal dependence of the viscosity coefficient. This method of determination is demonstrated for a series of n-alkanes C₆–C₂₀.List of symbols A, B, C parameters in empirical viscosity-temperature dependence - E molecular bond energies of liquid calculated from heat of evaporation in vacuum - E_v viscous flow activation energy - G activation Gibbs function of viscous flow - H_v heat of evaporation - H_vb heat of evaporation at boiling point - H viscous flow activation enthalpy - k Boltzmann constant - m weight of molecule - M relative molecular weight - N_A Avogadro constant - q total number of bonds in one mole of liquid - R gas constant - S_id entropy of one mole of compound in ideal gas state - S_sat entropy of one mole of compound in saturated vapour state - S activation entropy of viscous flow - T absolute temperature - T_c critical temperature - T_r reduced temperature - T_c critical volume - T_f free volume of liquid per molecule - V₀ molar volume of molecules - V_m molar volume of liquid - relative permittivity - viscosity - density - _r reduced density