A ground level interpretation of the dielectric behavior of diluted alcohol-in-carbon tetrachloride mixtures

The dielectric behavior at room temperature of alcohol/carbon tetrachloride binary mixtures over the whole composition range is analyzed in the low frequency domain (100 kHz). Methanol, ethanol, 1-, 2-propanol, and 1-pentanol are considered. The results are compared with the ideal case as described in the framework of Onsager theory [J. Am. Chem. Soc. 58, 1486 (1936)]. We find that the observed negative deviation from the ideal dielectric constant at high alcohol dilution is almost independent of the alcohol species. This behavior is interpreted as an effect of the presence of closed chainlike alcohol clusters. Good quantitative agreement is found with a simple lattice model describing the equilibrium distribution of alcohol clusters in the framework of the semigrand canonical ensemble. The observed dielectric behavior is then compared with the results of the calorimetric investigations carried out by Otterstedt and Missen [Trans. Faraday Soc. 57, 879 (1962)]. It is concluded that the dielectric and the calorimetric behaviors of these mixtures at high dilutions can be both interpreted consistently as effects of homogeneous association of the alcohol. (C) 2003 American Institute of Physics.