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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: bar0029 on April 19, 2011, 08:16:09 pm

Title: can anyone explain how to do this question..
Post by: bar0029 on April 19, 2011, 08:16:09 pm
Calculate the volume of ethene required to produce 100kg of polyethene at 25 degrees C and 250 atm pressure.

we haven't done this at school yet, i'm just working ahead, so this may be a relatively simple question, but i have yet to come across one like this and so i just need some assistance, please


:)
Title: Re: can anyone explain how to do this question..
Post by: m@tty on April 19, 2011, 08:21:38 pm
Use pV=nRT

convert 100kg of polyethylene into a molar quantity, 25 degrees C into K etc
Title: Re: can anyone explain how to do this question..
Post by: bar0029 on April 19, 2011, 08:23:00 pm
how would you convert it into a molar quantity, what is it's molar mass?
how do you relate the amount of polyethene to the amount of ethene
Title: Re: can anyone explain how to do this question..
Post by: Mao on April 19, 2011, 08:23:57 pm
The reaction of ethene --> polyethene has no by-products. The atomic efficiency is 100%, implying 100kg of polyethene = 100kg of ethene. The rest is just the gas equation.

@m@tty, GL finding a molar mass for polyethene :P
Title: Re: can anyone explain how to do this question..
Post by: m@tty on April 19, 2011, 08:25:23 pm
I didn't mean that Mao.. ::)

how would you convert it into a molar quantity, what is it's molar mass?
how do you relate the amount of polyethene to the amount of ethene

Well polyethene is just a bunch of ethene stuck together. So you can just consider it as ethene as no mass is lost due to the double bond (this is how it joins - no loss of hydrogen like other polymerisation reactions). So, use the molar mass of ethene.
Title: Re: can anyone explain how to do this question..
Post by: bar0029 on April 19, 2011, 08:43:25 pm
Thank-you so much!!!!!!
=)