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Homework Help: Materials/Chemistry Question - Weight % fractions

  1. Sep 24, 2007 #1
    Heres a question Im stuck with

    Crosslinked polymers consisting of 62 wt% ethylene and 38 wt% propylene may have elastic properties similar those for natural rubber. For a copolymer of this composition, determine the fraction of the ethylene mer.

    Express your answer with three decimal points.

    I honestly am lost with how to do this question...

    What I did was....

    Found the weight of ethylene (28.052) and the weight of propylene (42.078)...then multipled by the percentages and got...

    28.052*0.62 = 17.39
    42.078*0.38 = 15.98


    fraction = 17.39/(15.98+17.39)

    I doubt this is right...any help would be much appreciated.

    Thanks in advance!
    Last edited: Sep 24, 2007
  2. jcsd
  3. Sep 24, 2007 #2
    Sorry I think I posted this in the wrong section.

    My apologies
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