Relative permittivity of dipolar liquids and their mixtures. Comparison oftheory and experiment

An empirical extension, based on the Kirkwood-Frohlich equation, of a molec ular based second- order perturbation theory is proposed to calculate the r elative permittivity of dipolar liquids and mixtures in terms of the molecu lar dipole moment, the refractive index, density and temperature. Using the resulting equation, and giving an estimation for the dipole moments of the pure components, good agreement is obtained between the theoretical and ex perimental results for the relative permittivity of mixtures of carbonyl co mpounds with aprotic liquids. We show that our extension of the Kirkwood-Fr ohlich equation describes the dielectric properties of mixtures more accura tely than the original equation.