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239
To find R
G
, two more steps are needed. Returning to the main equation, we
start by extrapolating the data in the table to zero concentration:
Another set of extrapolated values is then obtained (and different from any of
those in Steps 1 and 2).
Step. 4.
The values for zero concentration obey the equation:
Kc
R
θ
⎛
⎝⎜
⎞
⎠⎟
c
=
0
=
1
+
16
π
2
R
G
2
3
λ
2
sin
2
θ
2
⎛
⎝⎜
⎞
⎠⎟ +
...
⎛
⎝⎜
⎞
⎠⎟
1
M
w
They are therefore a linear function of sin
2
(
θ
/2), and a plot of (Kc/R
θ
)
c=0
versus
sin
2
(
θ
/2) provides the necessary slope:
0.0E+00
5.0E-06
1.0E-05
1.5E-05
2.0E-05
2.5E-05
0.0000
0.0005
0.0010
0.0015
c (g/ml)
Kc/R
!
!
1
!
2
!
3
!
4
!
5