3.H.2. The Critical Exponents For Pure PVT Systems
There are 4 critical exponents of interest.
Degree of the Critical Isotherm,
where the subscript 0 denotes properties of
the ideal gas.
Degree of the Coexistence Curve,
is the order parameter. Experimentally,
Critical Exponent of the Heat
Capacity, α, α'
Isothermal Compressibility, γ
the mass density and m is the molar
weight, we can rewrite eq(3.40) as
now denotes specific heat (molar heat capacity /m). Since all terms on the
right are positive, we have
Now, when the critical point is approached
from below, we have
Taking the square of the last gives
On the other hand,
is expected to be regular, [see (3.26)], so
Putting everything into (3.89), we have
where the Aj's are constants.
Thus, the singular part of the logarithm of
which is known as the Rushbrook inequality.