DIELECTRIC-PROPERTIES OF BINARY-LIQUID SYSTEMS AT VERY DILUTE CONCENTRATIONS DETERMINED BY USING A STEPWISE DILUTION METHOD

A stepwise dilution method to determine the dielectric constant at a f requency of 1 MHz has been developed and the dielectric properties of benzene, ethanol, 1-butanol, chlorobenzene, dioctyl succinate, and sod ium bis(2-ethylhexyl) sulfosuccinate (AOT) in cyclohexane were determi ned at 298.15 K. From the precise measurements carried out for very di lute concentrations, it was found that there is a critical concentrati on for the threshold of solute-solute interactions at a mole fraction lower than 10(-3). Apparent dipole moments for polar liquids were calc ulated as a function of mole fraction. The limiting dipole moments mu( infinity) for polar molecules were determined from the dielectric cons tants at mole fractions lower than the critical concentration of the s olute-solute interactions by using the Debye and Frohlich equations, T he value of mu(infinity) for chlorobenzene calculated by the Frohlich equation agreed very well with literature values determined for the va por phase.