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ChemE 178:
Homework #5
Due Friday, October 17
1.) Consider a freelyjointed chain with a distance between joints of 0.6 nm.
.
a.) Compute the root mean square endtoend distance of such a chain that has 10000 links.
b.) Compute the radius of gyration of the chain in part a.)
c.) Suppose that the links in the chain can be completed aligned in a straight line, by
applying a force to the end of the chain, for example.
What is the endtoend distance of
this (stretched or aligned) chain?
2.)(similar to Y&L 3.5):
For the linear molecule of polyethylene with molecular weight 119,980
g/mol calculate
a.) The contour length
b.) The RMS end to end distance using a
freely jointed chain (FJC) model and a freely
rotating chain model.
c.) Calculate the radius of gyration for the FJC model.
d.) Compare the RMS endtoend distance and radius of gyration with the contour length
e.) The characteristic ratio (C
∞
) for polyethylene from the Polymer Handbook is 6.9.
What
RMS end to end distance does this imply?
What does this imply about
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This note was uploaded on 12/09/2011 for the course CHEM ENG 178 taught by Professor Segalman during the Fall '08 term at University of California, Berkeley.
 Fall '08
 SEGALMAN

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