Mixtures, solutions, and alloys

Characterization of mixtures

We consider mixtures, or solutions, or alloys with

v

constituents, which are characterized by a Greek index. Thus

p

α

is the partial pressure of constituent

α

,

ρ

α

its density, and

u

α

or

s

α

are the specific values of the internal energy and entropy, respectively. Pressure, density, internal energy density, and entropy density

of

the

mixture

are additively composed of the corresponding partial quantities

$ p=\sum\limits_{\alpha=1}^{v}p_{\alpha}, \rho = \sum\limits_{\alpha=1}^{v}\rho_{\alpha}, \rho{u} = \sum\limits_{\alpha=1}^{v}\rho_{\alpha}u_{\alpha}, \rho{s} = \sum\limits_{\alpha=1}^{v}\rho_{\alpha}s_{\alpha}. $

(8.1)

This does not mean, however, that

ρ

α

,

u

α

, and

s

α

are given by the constitutive functions of the pure constituent

α

. Indeed,

ρ

α

,

u

α

, and

s

α

will generally depend on

p

α

and

T

,

and on all the other

partial pressures

p

β

.