CHAPTER 9 MIXTURES
9.4 LIQUID ANDSOLIDMIXTURES OFNONELECTROLYTES 251
reference state b
0
0:1
0:2
0:3
0:4
0 0:2 0:4 0:6 0:8 1:0
xB
(a)
.
fB
=bar
kH,B
0
0:1
0:2
0:3
0:4
0 0:2 0:4 0:6 0:8 1:0
xB
(b)
.f
=xB
/=B
bar
Figure 9.7 Liquid solutions of 2,3-dimethylbutane (B) in cyclooctane at298:15K
and 1 bar.a
(a) Fugacity of B in an equilibrated gas phase as a function of solution composition.
The dashed line, tangent to the curve atxBD 0 , is Henry’s law behavior, and its slope
iskH,B.
(b) Fugacity divided by mole fraction as a function of composition; the limiting value
atxBD 0 is the Henry’s law constantkH,B.
aBased on data in Ref. [ 109 ].
is proportional to all three of these composition variables. This leads to three versions of
Henry’s law:
mole fraction basis fBDkH,BxB (9.4.16)
(nonelectrolyte solute
at infinite dilution)
concentration basis fBDkc;BcB (9.4.17)
(nonelectrolyte solute
at infinite dilution)
molality basis fBDkm;BmB (9.4.18)
(nonelectrolyte solute
at infinite dilution)
In these equationskH,B,kc;B, andkm;Bare Henry’s law constants defined by
mole fraction basis kH,B defD lim
xB! 0
fB
xB
(9.4.19)
concentration basis kc;B defD lim
cB! 0
fB
cB
(9.4.20)
molality basis km;B defD lim
mB! 0
fB
mB