How Many Moles of Polymer Are Formed?

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Discussion Overview

The discussion revolves around the calculation of moles of polymer formed from monomers, exploring various scenarios and interpretations of the problem. Participants engage in reasoning about molecular weights, reactions, and the implications of polymer formation, with a focus on theoretical and practical aspects of chemistry.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • Some participants express confusion about how to derive the number of moles of polymer from given data, particularly regarding the relationship between moles and the number of atoms in a mole.
  • There are discussions about the minimum number of monomers required to form a polymer, with some suggesting at least two monomers are necessary.
  • Participants propose hypothetical scenarios where all monomers react to form a single large molecule, leading to questions about how many moles this represents.
  • One participant suggests that if a reaction involves two monomers forming a polymer, starting with one mole of monomers would yield half a mole of polymer.
  • Another participant calculates the length of DNA if one mole of base pairs were unwound, leading to discussions about the astronomical lengths involved.
  • Some participants question the implications of crosslinking in polymers and how it affects the definition of a single molecule.

Areas of Agreement / Disagreement

Participants generally do not reach a consensus, as multiple competing views remain regarding the calculations and interpretations of polymer formation. There is ongoing debate about the implications of different scenarios and the definitions involved.

Contextual Notes

Limitations include assumptions about the reactions and the definitions of moles and polymers, as well as unresolved mathematical steps in the calculations presented by participants.

Who May Find This Useful

This discussion may be of interest to students and educators in chemistry, particularly those focused on polymer chemistry and stoichiometry, as well as individuals curious about theoretical implications of molecular interactions.

Janiceleong26
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  • Homework Statement

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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?
 
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Imagine you have two A. Can you make two pairs (AA) of the two A you have?
 
Choose a molecular weight for the monomer (say 100 g/mol) and play with the numbers.
 
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Borek said:
Imagine you have two A. Can you make two pairs (AA) of the two A you have?
No..
 
Janiceleong26 said:
No..

Do you see how it is related to the problem? And to the 1st answer?
 
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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?
 
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Borek said:
Do you see how it is related to the problem? And to the 1st answer?
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?
 
Chestermiller said:
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?
Erm, 1/ (no. of monomers joined) ?
 
Janiceleong26 said:
Erm.. Is it like for one polymer to form, we need at least two monomers?

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?
 
  • #10
Borek said:
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?
Chestermiller said:
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?
I'm not sure.. 1/(no. of moles of monomers) ?
 
  • #11
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.
 
  • #12
Borek said:
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.
1/(6.02x10^23)
 
  • #13
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?
 
  • #14
Borek said:
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?

1/2 mole of AA
 
  • #15
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?
 
  • #16
Borek said:
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?
Yup true. Thanks for the help
But what about option2? :biggrin:
 
  • #17
Reread what I wrote, the answer is there. Start with the word "everything".
 
  • #18
Borek said:
Reread what I wrote, the answer is there. Start with the word "everything".
OHHH... I see I see :woot:
Between 0.5 mole to 1/(6.02x10^23) mole , 10^-6 is within the range
Thanks !
 
  • #19
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:
  • #20
epenguin said:
...if it were extended in a line now far would a mole go...
Might it be on the order of light-days?
 
  • #21
Hm, question never said polymer can't undergo crosslinking. I have no problems assuming a huge object made of a crosslinked polymer is actually a single molecule.
 
  • #22
insightful said:
Might it be on the order of light-days?

Don't guess, this is trivial to estimate.
 
  • #23
Borek said:
Don't guess, this is trivial to estimate.
That wasn't a guess.
 
  • #24
I hoped Januce could discover and surprise herself. :oldsmile:
And pick up a useful habit.
 
  • #25
epenguin said:
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?
Sorry for the really late reply as i was busy with exams.

I'm not too sure if my working is right.. but this is what I did:

1 basepair has a length of 0.034nm
1 molecule of DNA has 220x10^6 base pairs, in 1 mol there would be 220x10^6 x 6.02 x10^23 =1.324 x 10^32 base pairs.
Length of 1 mol of DNA would be 1.324 x 10^32 x 0.034 nm = 4.50 x 10^21 m

I'm sorry, I am not too sure what you mean by how long is 1 mole if it's 1 molecule.. I thought 1 mole has 6.02 x 10^23 molecules?
 
  • #26
That is truly astrononomical. What I had actually meant was one mole of nucleotide or of basepairs.

When I worked that out (a single human chromosome unwound if it could be straightened but still the double-helical structure) this was already fairly astronomical, a large fraction of a light year. 1mole of DNA as you have calculated is a large mass and a huger length of zillions of light years.

The single human chromosome unwound if it could be straightened in this way is reckoned to be a few centimeters. The chromosome you see photos of in your genetics texts is of order, if I remember, a micron. Very condensed. (Though remember those pictures where they are seen and counted etc. are in a cell-cycle phase where they are most highly condensed.)
 

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