Properties of Binary Aqueous Cosolvent Mixtures

Mixtures of water with cosolvents are often used as solvents for electrolytes and ions so that those properties of the mixtures that are related to the (possibly preferential) solvation of the ions by the components of such mixtures need to be known. As for the neat solvents dealt with in the previous sections of this chapter, the discussion concerning those solvents marked as miscible with water in Table 3.10 involves physical and chemical properties, to be dealt with in turn. Much of the information below is adapted from the book by Marcus [56]. 

1 Physical Properties of Binary Aqueous Mixtures with Cosolvents 

The composition of binary aqueous mixtures with cosolvents S is usually expressed in terms of the mole fractions of the cosolvent and = 1 - Xj of the water. In some cases, because of the convenience of preparing mixtures by volume rather than by mass, where the mass fractions are and the volume fractions and are employed instead. The relationships between these measures of the composition are  

The physical properties of the binary mixtures are expressed by the general symbol Y that may represent extensive thermodynamic quantities such as molar 

Gibbs energies, enthalpies, entropies, heat capacities, and volumes, as well as intensive properties, such as permitlivities or viscosities. The excess functions of extensive properties over those for ideal mixtures of the components, symbolized by y (or the respective increments for intensive quantities, symbolized by AT), are usually defined in terms of the mole fraction composition with respect to the pure components  

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