1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Number of moles of polymer formed

  1. Nov 4, 2015 #1
    • 1. The problem statement, all variables and given/known data
    image.jpg

    2. The attempt at a solution

    I chose no. 1 only, but the answer is 2&3, I can't seem to see how 10^-6 came about. And for C, I'm not clear how it came about too.. Is it because 1 mole consists of 6x10^23 atoms, so no. of moles of the polymer is 1/(6x10^23) ? And why is 1 mole wrong?
     
  2. jcsd
  3. Nov 4, 2015 #2

    Borek

    User Avatar

    Staff: Mentor

    Imagine you have two A. Can you make two pairs (AA) of the two A you have?
     
  4. Nov 4, 2015 #3
    Choose a molecular weight for the monomer (say 100 g/mol) and play with the numbers.
     
  5. Nov 4, 2015 #4
    No..
     
  6. Nov 4, 2015 #5

    Borek

    User Avatar

    Staff: Mentor

    Do you see how it is related to the problem? And to the 1st answer?
     
  7. Nov 4, 2015 #6
    What would happen if the all the monomer reacted with itself to form one long gigantic molecule of enormous molecular weight. How many moles does 1 molecule represent?
     
  8. Nov 5, 2015 #7
    Erm.. Is it like for one polymer to form, we need at least two monomers? So it should be at least two moles till infinite? What about option 2?
     
  9. Nov 5, 2015 #8
    Erm, 1/ (no. of monomers joined) ?
     
  10. Nov 5, 2015 #9

    Borek

    User Avatar

    Staff: Mentor

    So, how many moles of the product you will get?

    Now try to answer Chester's question. Basically he is asking - 1 molecule, how many moles is it?
     
  11. Nov 5, 2015 #10
    I'm not sure.. 1/(no. of moles of monomers) ?
     
  12. Nov 5, 2015 #11

    Borek

    User Avatar

    Staff: Mentor

    1 molecule of anything - how many moles of that substance? Don't think about monomers and polymers for a while, this is a simple, basic question about moles as such.
     
  13. Nov 5, 2015 #12
    1/(6.02x10^23)
     
  14. Nov 5, 2015 #13

    Borek

    User Avatar

    Staff: Mentor

    OK, so, if everything reacted, you will get a single polymer molecule, or 1/6.02×1023 moles of product, yes?

    Now, if the reaction were exactly 2A→AA, and you started with 1 mole of A, how many moles of the AA polymer would be produced?
     
  15. Nov 5, 2015 #14
    1/2 mole of AA
     
  16. Nov 5, 2015 #15

    Borek

    User Avatar

    Staff: Mentor

    So, if there was a simplest reaction, there is no way 1 mole of polymer could be produced, right? But depending on the product everything between 1/2 mole of 1/6.02×1023 is possible, isn't it?
     
  17. Nov 5, 2015 #16
    Yup true. Thanks for the help
    But what about option2? :biggrin:
     
  18. Nov 5, 2015 #17

    Borek

    User Avatar

    Staff: Mentor

    Reread what I wrote, the answer is there. Start with the word "everything".
     
  19. Nov 5, 2015 #18
    OHHH... I see I see :woot:
    Between 0.5 mole to 1/(6.02x10^23) mole , 10^-6 is within the range
    Thanks !!
     
  20. Nov 7, 2015 #19

    epenguin

    User Avatar
    Homework Helper
    Gold Member

    OK 2 and 3 are both correct answers. But I think this is a case of "when you've got the answer it's not finished."
    2 is a typical possible figure I think for a polymer.
    For 3 I think the operative word in the question is theoretically.

    Would you care to work out how long is 1 mole if it's one molecule?
    I think macromolecules don't come longer than DNA. One fairly avverage human chromosome has 220X106 base pairs in a DNA molecule thought to be continuous. In the ordinary double-helical structure contains about 10 basepairs per turn and each turn is about 0.34 nm long. It normally folds back on itself, but if it were extended in a line now far would a mole go, would you care to work out and tell us?
     
    Last edited: Nov 7, 2015
  21. Nov 7, 2015 #20
    Might it be on the order of light-days?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Number of moles of polymer formed
Loading...