Handbook of Solvents - George Wypych - ChemTech - Ventech!

522 Y. Y. Fialkov, V. L. Chumak
Figure 9.4. Classification of isotherms of molar volume deviation from additivity for binary solvents.
then Δθ position of maximum is between xA values of 0.5 and 0.33 molar fractions. This
type of Δθ isotherm is most common for interacting binary liquid systems, for example, diethyl
aniline-halogen acetic acids.
Type III includes Δθ isotherms with a singular maximum. According to metrical analysis,
3 dependencies of this type are typical of systems where adduct formation constant,
K f →∞. Mustard oil-amine is an example of this behavior.
Relative extent of the interaction increases from systems with Δθisotherms of type I to
systems of type III isotherms. This conclusion comes from analysis of metrical molar volume
equations and comparison of binary systems composed of one fixed component and a
number of components, having reactivity towards fixed component changing in well-defined
direction.
9.3.2.4 Conductivity
The shape of specific conductivity relation on composition of the binary mixed solvent depends
on conductivity of the components and some other parameters discussed below. Because
of molar conductivity calculation of binary mixed solvent system, the ion associate
concentration should be taken into account (eq. [9.7]). This quantity is known in very rare
instances, 13,14 therefore, the conductivity of interacting mixed solvent is most often expressed
in specific conductivity terms.
Classification of conductivity shapes for binary liquid systems may be based on the
initial conductivity of components. Principal geometrical types of the conductivity isotherms
are presented in Figure 9.5.
The type I isotherm includes the concentration dependence of conductivity of the systems
(Figure 9.5).
These systems are not often encountered in research and technology practice. The type
I can be subdivided into subtype Ia - isotherms with a minimum (for example, selenic acidorthophosphoric
acid) and subtype Ib - isotherms with a maximum (for instance,
orthophosphoric acid-nitric acid).
The type II isotherms describe the concentration dependence of conductivity for binary
systems containing only one conductive component. In this case also, two geometric
subtypes may be distinguished. Subtype IIa - has monotonically convex shape (i.e., without
extreme) in the direction of the composition axis. The binary system, selenic acid-acetic
acid, can serve as an example of this kind of dependency. Subtype IIb includes isotherms
with a maximum (minimum) - most widespread kind of isotherms (for example: perchloric