Gas phase:

The gas-phase density is determined by the equation of state

(9–8)

Bulk phase:

For non–liquid-bulk phases, the physical-material density of each species in the corresponding bulk phase is specified in the surface/liquid chemistry input file within the specification of the bulk-species data block. It is then taken as constant (fixed). The volume and density for the non-liquid-bulk phase is still computed in the same manner as for an ideal mixture (see Equation 9–11 and Equation 9–12 below).

For species in a liquid-bulk phase, the density is computed using the density model specified by the thermodynamic data. It is thus computed either from a fitting equation (see Liquid Species ),

(9–9)

or from the Rackett density model (see Liquid Species )

(9–10)

Since the volume of an ideal liquid mixture is the sum of the volumes of its components,

(9–11)

the density of an ideal liquid mixture can be computed as

(9–12)