Chemistry Reference
In-Depth Information
by extrapolation:
π
C
2
Using the given data, plot
π
/
C
2
against
C
2
and find lim
C
2
-0
4
3
π
cm toluene
C
2
×
10
-2
2
g/cm
3
1.77
1
0
0
1
2
3 4
C
2
× 10
3
(g/cm
3
)
5
6
7
8
From the plot,
51:77310
2
π
C
2
cm toluene=ðg=cm
3
lim
c
2
-0
Þ
To convert the above value to SI units,
ρ
toluene
50:8610 g=cm
3
and ρ
Hg
513:53 g=cm
3
1 cm of toluene5 ð10Þð0:8610Þ=13:5350:6364 mm Hg
In addition; 1mmHg5133:3 Pa and 1 g=cm
3
51310
3
kg=m
3
0
@
1
A
5
ð
10
2
π
C
2
1
:
77
3
Þð
0
:
6364
Þð
133
:
3
Þ
lim
c
2
-0
1310
3
51:5310
1
Pa m
3
kg
21
Therefore,
M
N
5
ð
8
:
314
Þð
298
:
2
Þ
1
10
1
:
5
3
51:65310
2
kg=mol
The second virial coefficient follows from the slope of the straight-line portion
of the (
c
plot essentially by dropping the
c
2
(3-26)
.
It is to be expected that measurements of the osmotic pressures of the same poly-
mer in different solvents should yield a common intercept. The slopes will differ
π
/c
)
terms in
Eqs. (3-24)
