ρ and T as state variables
In some cases the molar density ρ is used instead of v. In this case V is readily replaced by ρ:
(79)
And:
(80)
As in Equation (64)
(81)
and make it molar by dividing by the total number of moles nT
(82)
Because x as well as ρ are again functions of n:
(83)
