Chemistry Reference
In-Depth Information
0.0
p
sat
-0.5
p
,MPa
50
-1.0
100
-1.5
-2.0
-2.5
200
300
400
500
600
700
800
Temperature, K
FIGURE 9.7
Experimental (symbols) and fitted (lines) results for Henry's constants (
H
21
) for
Hydrogen sulfide (2) in water (1) from Equation 9.37 through Equation 9.41. (Reprinted with
permission from A. Plyasunov, J. P. O'Connell, R. H. Wood, and E. L. Shock, 2000, Infinite
Dilution Partial Molar Properties of Aqueous Solutions of Nonelectrolytes. II. Equations for
the Standard Thermodynamic Functions of Hydration of Volatile Nonelectrolytes over Wide
Ranges of Conditions Including Subcritical Temperatures,
Geochimica Et Cosmochimica
Acta
, 64, 2779, With permission from Elsevier.)
Shock, and O'Connell 2006). Figure 9.7 shows results for H
2
S in water at various
pressures and temperatures.
The alternative route to aqueous solute properties based on FST was to use a
finite pressure reference state where properties could be obtained, and compute
the difference in Gibbs energy between the desired state and the reference state
(Sedlbauer, O'Connell, and Wood 2000). This allows calculations for electrolytes,
which would not have second virial coefficients that could be used at low densities as
in Equation 9.41. The relation here for
A
Kr
is similar to Equation 9.41,
(
)
(
)
+
+
0
A
=−
1
ββ
1
−
C
Kr
1
1
11
(9.42)
{
}
(
+
(
)
−
(
)
ρβ
+
β exp
1500
/
T
+
β
exp
c
ρ
δ
exp
c
ρ
1
2
3
4
1
2
where values of
c
1
and
c
2
are universal constants and β
1
, β
2
, β
3
, and β
4
are solute-
dependent parameters. The value of δ has a specific value for the class of solute:
cation, anion, nonelectrolyte.
Again, analytic expressions for Δ
h
G
2
∞
and
H
21
are found using Equation 9.37
through Equation 9.39 (Sedlbauer, O'Connell, and Wood 2000), though slightly dif-
ferently than by Plyasunov et al. (Plyasunov, O'Connell, and Wood 2000; Plyasunov
et al. 2000). The modification to deal with temperatures below the critical is to add
