October 28, 2021, 04:15:13 PM
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Topic: problem on polymers i can't solve  (Read 245 times)

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LucaZombini

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problem on polymers i can't solve
« on: September 07, 2021, 11:55:43 AM »
983,98g of a polymer C2n+2H4n+6On+1 solid are brought to gas form at 442,71K. the volume occupied by the gas at 0,416546 bar is 12,4 dm3. calculate the number of monomers which are part of the polymer.

by using the ideal gas formula i get the n = 0,14 mol, then i've calculated the monomer's weight putting n = 0 and i obtained 46 g*mol-1. dividing the polymer's weight per the mole number i found i get MP = 7028,42 gmol-1. by dividing the polymer's molecular mass with the monomer's molecular mass i get n=152,8 but the result should be 158.

Borek

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Re: problem on polymers i can't solve
« Reply #1 on: September 07, 2021, 01:00:32 PM »
Question doesn't make any physical sense (gas with molar mass of 7kg/mol? no way, the only gaseous product could be that of the decomposition). Using numbers with so many digits looks off as well.

But the only thing that looks wrong in logic of your calculation is n=0 - nope, monomer means n=1.

Not that it makes the result closer to 158, quite the opposite.
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