If they ask about the production of polyethylene (1 Viewer)

[vds700]

Do we talk about the older gas phase process (LDPE) or the Zeigler Natta process (HDPE)?

I have seen a question about this, but success one didnt talk specifically about either, just how an initiator activavates an ethylene molecule and other molecules join onto this. But the conditions are slightly different for the 2, so just wondering which you should talk about.

 

[pooja_107]

i think we should talk about both...cause they are for the production of LDPE and HDPE..unless they speciacilly ask us...just know both processes well

 

[eddy11]

i think only one is generally necessary to know well, just be aware of how the different processes produce different chain lengths affecting properties

 

[JasonNg1025]

Different chemical conditions produce different chain structures. For LDPE, the chain structures involve heavy branching, meaning there's more space between the chains accounting for its low density. For HDPE, the chain structures have very little branching, meaning they pack together closer and have a higher density

EDIT: Ok, I got the conditions

LDPE - Peroxide catalyst with an O-O bond that breaks the double bond open allowing for initiation / propagation, high pressure.

HDPE - transition metal catalysts and low pressure enabled more ordered orientation of chains

 

[danz90]

i think only one is generally necessary to know well, just be aware of how the different processes produce different chain lengths affecting properties

Yeah, I thought the same.

For example, high gas pressures and higher temperatures produces HDPE ? (not 100% sure on this, have to read over notes again later on). And they use different transition metal catalysts to produce HDPE, and LDPE.

Although all of the addition polymerisation begins with a peroxide radical for initiation, to produce an activated monomer. Then the propagation, and then finally termination.

 

[Zippora]

Yeah, I thought the same.

For example, high gas pressures and higher temperatures produces HDPE ? (not 100% sure on this, have to read over notes again later on). And they use different transition metal catalysts to produce HDPE, and LDPE.

Although all of the addition polymerisation begins with a peroxide radical for initiation, to produce an activated monomer. Then the propagation, and then finally termination.

no, high gas pressure and higher temps produces LDPE

 

[JasonNg1025]

Yeah I agree with Zippora
High pressure is LDPE
Hey, doesn't high temperature mean low pressure due to that ideal gas law thing?

 

[fyoun123]

^^

You did 4u maths in year 9??

 

[JasonNg1025]

Yeah........

 

[danz90]

no, high gas pressure and higher temps produces LDPE

yeh most likely.. I ALWAYS get them mixed up lol

 

[axlenatore]

no, high gas pressure and higher temps produces LDPE

yup chains branch and cant pack therefore it has low density but the catalyst in HDPE allows linear chains to form with dispersion forces cause to pack together into HDPE

 

[danz90]

I reckon this topic area will be in MC this year, not short answer responses, considering there was a 5 or 6 marker on this stuff in last year's paper.

 

[axlenatore]

I reckon this topic area will be in MC this year, not short answer responses, considering there was a 5 or 6 marker on this stuff in last year's paper.

Meh prepare for anything

 

[JasonNg1025]

I like that philosophy.
I'm not sure if I'm gonna make money this year, my teacher betted, any money that they're gonna give a long answer question on comparing dry cell/lead acid cell with one of that huge list. If she's wrong, I won't go hard on her, because she just gave birth xD

 

[danz90]

Meh prepare for anything

haha true ay.

I like that philosophy.
I'm not sure if I'm gonna make money this year, my teacher betted, any money that they're gonna give a long answer question on comparing dry cell/lead acid cell with one of that huge list. If she's wrong, I won't go hard on her, because she just gave birth xD

lol yeh its quite a possibility.. since the last time I saw one was in like 2001 or 2002. They haven't had a longer response on batteries for quite a while ay?

 

[axlenatore]

haha true ay.



lol yeh its quite a possibility.. since the last time I saw one was in like 2001 or 2002. They haven't had a longer response on batteries for quite a while ay?

Yer ive only seen sort ones, like the oxidation equation from one of them

 

[danz90]

Yer ive only seen sort ones, like the oxidation equation from one of them

I would love to have an ordinary 6 marker, comprised up of separate parts, including:

- Draw a galvanic cell (3 marks)
- Calculate the cell potential (2 marks)
- Explain why..... (1 mark)

Would be awesome. But then again, stupid BOS chooses the questions. Then again, we could be loving the BOS for slipping us a nice and straightforward exam (with hopefully not too many extended responses :burn: )

 

[SkimDawg]

I like that philosophy.
I'm not sure if I'm gonna make money this year, my teacher betted, any money that they're gonna give a long answer question on comparing dry cell/lead acid cell with one of that huge list. If she's wrong, I won't go hard on her, because she just gave birth xD

They had it in the 2007 paper, but then again, bos can be lame and repeat qu's that everyone went bad on the previous year

 

[JasonNg1025]

I don't think they had that 7marker though
I can't remember doing that in the 2007 :O
Oh well

 

[eddy11]

i want a big haber process question, or one about drinking water