Handbook of Solvents - George Wypych - ChemTech - Ventech!

518 Y. Y. Fialkov, V. L. Chumak
Figure 9.2. Classification of permittivity isotherms for binary solvents: 1 and 2 - isotherms for systems with interaction
and without interaction, respectively.
associates can be found in a specialized monograph. 3
In theory, if composition of the mixture is known, then calculation of any characteristic
property of the multi-component mixture can be performed by the classical physical and
chemical analysis methods. 3 For binary liquid system, it is possible only if all chemical
forms (including all possible associates), their stoichiometry, stability constants, and their
individual physical and chemical properties are well determined. A large volume of correct
quantitative thermodynamic data required for these calculations is not available. Due to
these obstacles, data on permittivity, viscosity and other macro-properties of mixed solvents
with interacting components are obtained by empirical means. Data on empirical
physical properties of liquid systems can be found in published handbooks. 1,2,10 Principles
of characteristic changes due to the compositional change of liquid mixtures with interacting
components are discussed here. Assessment of nature of such interactions can only be
made after evaluation of the equilibrium constant (energy) of such interactions between solvents.
9.3.2.1 Permittivity
Permittivity, ε, is the only property of the mixed liquid systems with chemical interaction
between components that has not been studied as extensively as for systems without chemical
interaction. 10 When interaction between components is similar to a given in equation
[9.8], formation of conductive solutions occurs. Determination of ε for these solutions is
difficult, and sometimes impossible. Although, more or less successful attempts to develop
such methods of permittivity determination are published from time to time, the problem
until now has not been solved.
Classification of the isotherms ε vs. composition of liquid systems 3 is based on deviations
of the experimental isotherms, which are then compared with isotherms of the system