Chemistry Reference
In-Depth Information
F
ðcÞ
p
The final result for the osmotic coefficient
(on molarity scale) is:
2
1
b
F
ðcÞ
p
¼
for
l
1
(44)
2
l
and:
2
1
þ b
F
ðcÞ
p
¼
for
l >
1
:
(45)
2
l
Figure
10
shows the osmotic coefficient of an aqueous solution of a single
polyelectrolyte as a function of the molarity of the repeating units
c
m
¼nc
p
and
the charge density parameter
l
. In a highly diluted aqueous solution (i.e., when
g
LK
!1
), the final result is:
2
F
ðcÞ
p
¼
1
for
l
1
;
(46)
1
2
l
F
ðcÞ
p
¼
for
l >
1
:
(47)
For the calculation of the osmotic pressure of an aqueous solution of a single
polyelectrolyte where the repeating unit is a 1:1 electrolyte one needs:
For the polyelectrolyte: the radius of the hard polymer rod
a
, the length of the
polymer rod
h
(or the length of a cylindrical monomer
b
and the number of such
monomers in a polyelectrolyte molecule
n
)
Fig. 10 Theory of Lifson and Katchalsky: Osmotic coefficient of an aqueous solution of a single
polyelectrolyte as a function of the charge density parameter
l
