Chemistry Reference
In-Depth Information
30
250
T
= 643 K
CsBr
25
200
T
= 673 K
T
= 703 K
Exp. data
20
150
15
10
100
5
50
0
0
-5
-10
-50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Solvent Density (g/cm
3
)
FIGURE 8.11
Behavior of
N
2,ex
(SR) and ρ
-1
(
C
12
-
C
11
) for an infinitely dilute CsBr aqueous
solution as a function of the solvent density along three supercritical isotherms in comparison
with experimental data. (Data from J. Sedlbauer, E. M. Yezdimer, and R. H. Wood, 1998,
Partial Molar Volumes at Infinite Dilution in Aqueous Solutions of NaCl, LiCl, NaBr, and
CsBr at Temperatures from 550 K to 725 K,
Journal of Chemical Thermodynamics
, 30, 3.)
Vertical arrow indicates the estimated critical density of the model solvent.
(
)
∞
o
o
o
∞
DD VC C
=+
ν
−
21
11
1
11
12
o
o
∞
=−
DVN
ex
SR)
(
11
12
,
(8.26)
(
)
∞
o
IG
o
=+
DV
κ
∂∂
px
11
T
1
2
T
,
ρ
o
∞
o
=+
DV
()
SR
−
ν
V
11
2
1
with
(
)
o
o
IG
DV
T
=
κκ
(8.27)
11
1
T
Note that
D
11
can be thought of as the (Lewis-Randall) ideal solution counterpart
of
D
21
, that is, when all 22, and 12 interactions are identically the same as those of
the pure solvent, 11. A closer look at Equations 8.26 and 8.27 in the context of the
observed behavior for the density dependence of the solvation quantities
N
2,ex
(SR)
and ρ
-1
(
C
12
-
C
11
) suggests that a more appropriate regression quantity than
D
21
(
T
,ρ)
would be Δ
D
21
≡
D
21
-
D
11
, since this quantity depends exclusively on the solute-sol-
vent molecular asymmetries, that is,
(
)
∞
o
o
11
∞
∆
DVCC
21
=
ν
−
(8.28)
1
12
