Homework 3
Due Tuesday, 9/28/10
1. Calculate molecular weight from the following viscosity data for polystyrene.
You
should provide a table showing your calculations of the different viscosities, a plot of the
data to determine molecular weight, and the value for the molecular weight that you
calculate.
The values for K and a are: K=0.000113 dL/g, a=0.73
Some hints: The calculations will go quicker if you use a spreadsheet to calculate all the
viscosities.
You should also use an appropriate graphing program or calculator which
will do linear regression in order to calculate the molecular weight.
"Eyeballing" a line
through a set of data points is not an acceptable means of finding the slope and intercept.
c
(g/dL)
time
(sec)
0.000
24.74
0.080
30.00
0.120
32.95
0.160
35.98
0.200
39.18
2.
a. In analyzing a solution of poly(ethylene terephthalate), you find that all chains have
one end which is an acid group, and that the total concentration of acid groups in the
solution is
1.00x10
3
mol/L.
If the solution contains 25.0 g/L of polymer, what is the number
average molecular weight of the polymer?
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 Fall '10
 Douglass
 Polymer, Entropy, Copolymer

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