Chemistry Reference
In-Depth Information
The ionic strength is:
2
X
k
1
m
k
m
z
k
:
I
m
¼
(162)
¼
CI
;
F
The contribution from short-range interactions to the activity coefficient of
solute species (i.e., groups)
i
,
vdW
i
G
;
is taken from the VERS model:
X
2
M
w
q
i
q
w
Y
L
Y
w
a
ð
0
Þ
i;L
a
ð
1
Þ
i;L
vdW
i
ln
G
¼
þ
f
1
ð
I
m
Þ
all groups L
2
X
X
z
i
M
w
Y
L
Y
w
Y
k
Y
w
a
ð
1
Þ
f
2
ð
I
m
Þ
(163)
L;K
all groups L
all groups k
X
X
3
q
i
q
w
Y
L
Y
w
Y
k
þ
Y
w
b
i;L;K
2
ð
M
w
Þ
all groups L
all groups k
with:
p
exp
p
and
1
2
I
m
f
1
ð
I
m
Þ¼
1
1
þ
2
I
m
2
I
m
(164)
exp
p
p
1
4
I
m
f
2
ð
I
m
Þ¼
1
1
þ
2
I
m
þ
2
I
m
2
I
m
(165)
The sum in (
163
) is over all solute species, i.e., nondissociated repeating units
C
,
nondissociated repeating units
D
, dissociated repeating units
F
and counterions CI.
M
w
is the relative molar mass of water divided by 1,000 (
M
w
¼
0.018016). Sub-
script
w
stands for water and
q
i
is the surface parameter of species
i
. The surface
fraction of a group
L
is abbreviated by
Y
L
. As the mixture consists of species
C
,
D
,
F
, CI and water, the following relative surface ratios are required:
Y
C
Y
w
¼
M
w
nk
m
p
q
rp
m
q
w
;
(166)
Y
D
Y
w
¼
m
p
q
rp
m
q
w
;
M
w
nð
k
aÞ
1
(167)
Y
F
Y
w
¼
m
p
q
rp
m
q
w
;
M
w
na
(168)
Y
CI
Y
w
¼
m
p
q
CI
m
q
w
:
M
w
na
(169)
