Refractive Indices Measurement and Correlation for Selected Binary Systems of Various Polarities at 25 degree C

New refractive indices at 25 degree C were measured and are reported here for 19 binary mixtures of pentan-3-one+1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane, +trichloromethane, +1,1,1-trichloroethane, +1,1,2,2-tetrachloroethane; cyclopentanone+1-chlorobutane, +1,1,2,2-tetrachloroethane; cyclohexanone+1,1,2,2-tetrachloroethane; 5-chloro-2-pentanone+n-hexane, +toluene, +ethylbenzene; nitromethane+trichloromethane; and nitromethane or nitroethane, +1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane. The experimental refractive index deviations from linear mixing behavior have been evaluated and correlated consistently with the 3-parameter RedlichaKister equation with good results. The molar refraction was also examined for the systems including pentan-3-one, cyclopentanone, cyclohexanone and 5-chloro-2-pentanone for which densities and excess molar volumes are available from previous works. Different theoretical (n, I) mixing rules were tested for these systems. The excess Gibbs energy G E and excess enthalpy H E values were considered together with the excess molar volumes V E, excess refractive indexes $ n_{\text{D}}\text{E}} $ , molar refraction R and excess molar refractions R E on mixing in the discussion of the influence of the alkyl chain length or of the nature of the second component in the mixture in terms of molecular interactions.