HSC Chemistry€¦ · HSC Chemistry Production of Materials ! Lesson!2:!!...

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HSC Chemistry

Production of Materials !Lesson!2:!!Polymerisation!of!Ethylene!

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! ! !0466 342 939 [email protected] www.synergyhsc.com

!Name: _____________________

LESSON!2:!Production!of!Materials!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!HSC!CHEMISTRY!!

Copyright!© HSC Synergy Education 2016! 2!

Summary!of!Key!Words!

Account!Account!for:!state!reasons!for,!report!on.!Give!an!account!of:!narrate!a!series!of!events!or!transactions!

Analyse!Identify!components!and!the!relationship!between!them;!draw!out!and!relate!implications!

Apply!Use,!utilise,!employ!in!a!particular!situation!

Assess!Make!a!judgement!of!value,!quality,!outcomes,!results!or!size!

Calculate!Ascertain/determine!from!given!facts,!figures!or!information!

Clarify!Make!clear!or!plain!

Classify!Arrange!or!include!in!classes/categories!

Compare!Show!how!things!are!similar!or!different!

Construct!Make;!build;!put!together!items!or!arguments!

Contrast!Show!how!things!are!different!or!opposite!

Deduce!Draw!conclusions!

Define!State!meaning!and!identify!essential!qualities!

Demonstrate!Show!by!example!

Describe!Provide!characteristics!and!features!

Discuss!Identify!issues!and!provide!points!for!and/or!against!

Distinguish!Recognise!or!note/indicate!as!being!distinct!or!different!from;!to!note!differences!between!



! Lesson!Dotpoints!By!the!end!of!the!lesson,!you!should!understand!the!following!concepts:!!Producing!Ethylene!!•! Identify!that!ethylene!serves!as!a!monomer!from!which!polymers!are!made!•! Identify!polyethylene!as!an!addition!polymer!and!explain!the!meaning!of!this!

term!!Polymerisation!!•! Identify!polyethylene!as!an!addition!polymer!and!explain!the!meaning!of!this!

term!•! Outline!the!steps!in!the!production!of!polyethylene!as!an!example!of!a!

commercially!and!industrially!important!polymer!!!

Properties!of!Polymers!!•! Describe!the!uses!of!the!polymers!made!from!the!monomers!(vinyl!chloride!

and!styrene)!in!terms!of!their!properties!!!!!!!!!!!!!!!!!!!!!!!



1.!Producing!Ethylene!!

CHECKPOINT:!

!! Monomers!!•! A!monomer!is!a!molecule!that!forms!the!basic!unit!for!________________!

!•! Monomers!bind!together!to!other!_______________________!to!form!a!_________________!

chain!molecule!called!a!polymer!!

•! Provide!an!example!of!a!monomer.!!!!!!•! There!are!two!types!of!monomers!that!you!learn!about!in!year!12:!!Type!A!–!Doubled!Bonded!Monomers!!•! The!first!type!are!monomers!with!double!bonds!!

!•! Below!are!some!examples!of!double!bonded!monomers.!Name!them.!!!

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• Identify!that!ethylene!serves!as!a!monomer!from!which!polymers!are!made!• Identify!polyethylene!as!an!addition!polymer!and!explain!the!meaning!of!this!term!!

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•! Other!than!the!double!bond!what!other!distinctive!feature!is!there?!!!!!

!!Type!B!–!Functional!Group!Monomers!!•! The!second!type!are!monomers!with!functional!groups!!

!•! Below!are!some!examples!of!monomers!with!functional!groups.!Name!them.!!

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!! Polymers!

!•! Polymers!are!long!chain!molecules!made!up!of!repeating!units!of!________________!

!•! Polymers!are!sometimes!called!macromolecules.!Explain!why.!!!!!!•! Examples!of!polymers!include:!

!Y! Polyethylene!Y! Polyvinyl!chloride!Y! Cellulose!

!•! There!are!TWO!TYPES!of!polymers!and!are!called:!

!Y! Addition!polymers!!Y! Condensation!polymers!

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2.!Polymerisation!!

CHECKPOINT:!

!! Addition!Polymers!!

!•! An!addition!polymer!is!made!when!________________________!molecules!are!_________!

together!!

•! Addition!polymers!are!also!known!to!be!called!synthetic!polymers.!Explain!why.!!!

!!!!•! Name!a!type!of!addition!polymer.!

!!!!!•! Another!way!to!look!at!addition!polymerisation!is!when!___________________!

carbon!(organic)!molecules!form!a!long!chain!polymer!molecule!!!

•! There!are!two!main!ways!in!which!addition!polymers!are!formed:!!

1.! Using!an!___________________!!!

2.! Using!a!____________________!!!!!!!!!!!

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• Identify!polyethylene!as!an!addition!polymer!and!explain!the!meaning!of!this!term!• Outline!the!steps!in!the!production!of!polyethylene!as!an!example!of!a!

commercially!and!industrially!important!polymer!!!



•! Below!is!an!example!of!the!addition!polymersation!process!to!produce!polyethylene.!!

!!!!!!!!!!!!!!!!!!!!•! A!catalyst!or!initiator!is!needed!to!produce!polyethylene.!Label!in!which!part!

of!the!process!is!this!needed.!!!Y! Explain!the!use!of!the!catalyst!in!the!process.!!

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Applications!2.1!!Question!1!!a)! Explain!the!concept!of!monomers.!(1!mark)!

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!!b)! Explain!the!concept!of!polymers.!(1!mark)!!!!!

!!Question!2!!!a)! Briefly!compare!two!types!of!monomers.!(2!marks)!!!!!

!!b)! Identify!two!types!of!polymers.!(1!mark)!!!!Question!3!!a)! Describe!the!addition!polymerisation!process.!(2!marks)!!!!!!!!!b)! Name!one!monomer!and!the!polymer!it!becomes!through!addition!

polymerisation.!(1!mark)!!

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! LDPE!and!HDPE!!•! There!are!two!main!types!of!polyethylene:!

!Y! Low!density!polyethylene!(LDPE)!Y! High!density!polyethylene!(HDPE)!!

•! Both!of!these!polymers!have!different!properties!allowing!them!to!have!different!properties!and!are!also!made!slightly!differently!!

!Low!Density!Polyethylene!!!•! LDPE!occurs!when!there!are!small!chains!that!branch!off!from!the!main!chain!!

!•! Below!is!a!diagram!of!LDPE:!

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!!•! Label!the!branching!on!LDPE!in!the!diagram!above.!!

!•! Simplify!the!diagram!above!to!show!how!LDPE!interacts!with!other!LDPE!

polymers.!!

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•! Identify!the!types!of!intermolecular!forces!that!interact!between!LDPE!chains.!!

!!!!•! The!branches!for!LDPE!can!be!short!or!long!and!their!presence!means!that!

LDPE!is!_________________!to!closely!pack!together!!!

•! LDPE!is!known!to!be!amorphous.!Explain!what!this!term!means.!!

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Y! Since!LDPE!is!amorphous!it!has!low!_____________________!!!

Y! Only!about!40!–!55%!of!LDPE!has!crystalline!regions!!!•! Since!LDPE!has!a!low!crystallinity!it!is!much!more!softer!and!flexible!!

!•! LDPE!has!a!relatively!low!melting!point!of!approximately!80℃.!Explain.!!!!!!!•! Based!on!each!of!the!properties!LDPE!has!its!uses.!Fill!in!the!rest!of!the!table.!!

!! Properties! Significance! Uses!

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!Low!

crystallinity!!

!Low!density,!flexible!

and!soft!

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!Low!Melting!Point!

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!Waterpoof!

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!Chemically!inert!

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High!Density!Polyethylene!!!•! HDPE!occurs!when!there!is!very!small!amounts!or!no!side!branching!

occurring!!•! Below!is!a!diagram!of!HDPE:!

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•! Simplify!the!diagram!above!to!show!how!HDPE!interacts!with!other!HDPE!polymers.!

!!!!!!!!!!!!!•! Identify!the!types!of!intermolecular!forces!that!interact!between!HDPE!chains.!

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•! HDPE!has!a!crystallinity!of!80!–!95%.!Explain!why.!!

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!!•! Since!HDPE!has!a!high!crystallinity!it!is!much!more!_____________!!

!•! HDPE!has!a!relatively!high!melting!point!of!approximately!135℃.!Explain.!!

!!!!!•! Based!on!each!of!the!properties!HDPE!has!its!uses.!Fill!in!the!rest!of!the!table.!!

!! Properties! Significance! Uses!

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!High!

crystallinity!!

!Rigid!

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!High!Melting!Point!

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!Chemically!inert!

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Applications!2.2!!Question!1!!Explain!why!low!density!polyethylene!can!be!used!to!make!cling!wrap.!(3!marks)!!!!!!!!!Question!2!!Explain!why!high!density!polyethylene!can!be!used!for!water!pipes.!(3!marks)!!!!!!!!!Question!3!(HSC!2006!–!Qu!20!Modified)!!Analyse!why!ethylene!is!such!an!important!starting!material!for!the!chemical!industry.!In!your!answer,!include!relevant!chemical!equations,!and!a!description!of!two!types!of!polymers!that!can!be!prepared!from!ethylene.!Link!the!polymers!uses!with!their!properties.!!!!

Marking!Criteria! Marks!!

•! Provides!characteristics!and!features!of!the!use!of!ethylene!as!a!starting!material!for!addition!reactions!

•! Relates!the!reactivity!of!the!double!bond!of!ethylene!to!its!widespread!use!in!the!chemical!industry!for!production!of!new!materials!and!fuels!

•! Provide!characteristics!and!features!of!the!use!of!ethylene!as!starting!material!for!production!of!polyethylene!

•! Explain!how!the!properties!of!LDPE!and!HDPE!are!derived!•! Relates!the!properties!of!the!polymers!to!its!uses!!

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! Production!of!HDPE!and!LDPE!!•! The!production!process!of!HDPE!and!LDPE!are!slightly!different!

!•! One!process!uses!an!initiator!while!the!other!uses!a!catalyst!

!•! However,!both!follow!a!similar!general!process.!For!each!of!the!steps!below!

explain!what!is!occurring.!!

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Initiation!

Chain!Propagation!

1!

2!

Termination!3!



Production!of!LDPE!!•! LDPE!is!produced!through!a!process!called!the!Higher!Pressure!Process!!

!•! The!parameters!for!producing!LDPE!include:!

!Y! Temperatures!of!about!200℃!!Y! Pressures!of!about!2000!atmospheres!Y! An!oxygen!based!initiator!!

!•! An!example!of!an!oxygen!initiator!is!tert!Y!butyl!peroxide!as!shown!below!(not!

examinable):!!!

!!!!!!!!!•! Using!the!oxygen!initiator!show!how!LDPE!is!formed.!!

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!!!!!!!!!!!!Production!of!HDPE!!•! HDPE!is!produced!through!a!process!called!the!Ziegler!–!Natta!process!!

!•! The!parameters!for!producing!HDPE!include:!

!Y! Temperatures!of!about!60!–!80!℃!!Y! Pressures!of!about!20!atmospheres!Y! Uses!a!Zielger!–!Natta!Catalyst!called!ionic!titanium!chloride/triethyl!

aluminum!!!•! The!example!below!shows!the!Ziegler!–!Natta!catalyst!used!in!production!of!

HDPE:!!!!!

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Applications!2.3!!Question!1!(HSC!2003!–!Qu!17!Modified)!!The!flowchart!shows!the!production!of!polyethylene.!!!!!!!!!!!!!!!!!

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a)! Describe!Process!Y.!!!

Marking!Criteria! Marks!•! Provides!a!thorough!description!of!the!three!key!steps!in!free!radical!addition!polymerisation!or!the!steps!in!Ziegler/Natta!polymerisation!

!3!

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A!sample!of!polyethylene!was!produced!by!Process!Y.!The!following!graph!shows!the!distribution!of!molecular!weights!of!polymer!molecules!in!the!sample.!

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b)! Why!is!a!range!of!molecular!weights!observed?!(1!mark)!!

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3.!Properties!of!Polymers!!

CHECKPOINT:!

!! Selecting!Polymers!

!•! When!selecting!a!polymer!it!is!important!to!consider!not!only!its!chemical!or!

physical!properties!but!also!its!cost!!

•! Polymers!are!a!multi!–!billion!dollar!industry!and!so!therefore!we!want!the!lowest!cost!one!!

•! However,!apart!from!cost!the!structure!of!the!polymers!are!very!important!as!it!directly!impacts!the!physical/chemical!properties.!These!include:!

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• Describe!the!uses!of!the!polymers!made!from!the!monomers!(vinyl!chloride!and!styrene)!in!terms!of!their!properties!!

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!Molecular!Weight!

!Crystallinity!

!Chain!Stiffening!!

!Cross!–!linking!!

!Melting!Point!

!Stability!to!Heat!&!Light!

!Mechanical!Strength!

!Flexibility/Rigidity!

!Chemical!Stability!



! Molecular!Weight!!•! The!molecular!weight!of!a!polymer!is!defined!by!its!__________________!!

!•! The!_________________!the!chain!length!the!___________________!the!molecular!

weight!!!•! The!higher!the!molecular!weight!the!more!___________________!forces!between!

chains!!!

•! How!does!a!high!molecular!weight!affect!the!melting!point!and!rigidity?!!

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•! Fill!in!the!following!flowchart.!!!!!!

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Higher!MW!

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! Chain!Branching!!•! Chain!branching!occurs!polyethylene,!in!which:!

!Y! High!branching!gives!us!___________!

!Y! Low/no!branching!gives!us!___________!

!Little!or!No!Branching!!•! Little!or!no!branching!allows!polyethylene!to:!

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Y! Leading!to!an!orderly!arrangement!allowing!substance!to!be!_________________!!

•! A!high!crystallinity!leads!to!several!things!including:!!Y! High!density!Y! High!melting!point!Y! Relatively!hard!substance!!

•! Draw!what!little!or!no!branching!looks!like.!!!!!!!!!!!!!!!!!!!!!!



Branching!!•! Branching!causes!polyethylene!to:!

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Y! Leading!the!substance!to!be!______________________!!

•! A!low!crystallinity!leads!to!several!things!including:!!Y! Low!density!Y! Low!melting!point!Y! Relatively!soft!substance!

!•! Draw!what!branching!looks!like.!!

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•! Fill!in!the!following!flowcharts.!!!!!!

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No!Branching!

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Branching!

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! Chain!Stiffening!!•! Chain!stiffening!occurs!when!a!larger!side!group!is!introduced!into!a!linear!

chain!resulting!in!the!reduction!of!___________________!!Y! What!happens!to!the!crystallinity!when!a!side!group!is!introduced?!

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Y! How!about!the!rigidity?!!

!!!•! Polystyrene!is!an!example!of!a!substance!that!has!side!groups!!

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!!•! What!is!the!side!–!groups!of!polystyrene!called?!!!!!•! Below!shows!what!the!side!group!actually!looks!like:!

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•! Are!the!side!groups!polar!or!non!–!polar?!!

!!•! Side!groups!increase!the!dispersion!forces!of!the!polymer.!Show!this!on!the!

first!diagram!on!this!page.!!!

•! Side!groups!are!what!we!call!BULKY!!

•! Fill!in!the!following!flowchart.!!!!!!

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Side!Groups!

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! Cross!–!Linking!!!•! Cross!–!linking!mostly!only!affect!________________________!!

!•! These!types!of!polymers!are!able!to!align!themselves!together!allowing!them!

to!interact!based!on!hydrogen!bonding!!!

•! Show!how!cross!–!linking!occurs!in!the!diagram!below.!!!!!!!!!!!!!!!!

•! Cross!–!linking!increases!the!rigidity!of!the!polymer!!!

!! Solubility!of!Addition!Polymers!!

!•! What!are!the!types!of!intermolecular!forces!that!occur!between!addition!

polymers?!!!!!!•! Consequently,!these!types!of!polymers!are!_______________!in!water!and!are!

water!–!repelling!!!Y! They!are!_____________________!

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4.!Properties!of!Polymers!!

CHECKPOINT:!

!! Polyvinyl!Chloride!(PVC)!

!•! Vinyl!chloride!is!the!common!name!given!to!a!monomer!that!makes!up!a!

polymer!called!PVC!!

•! Draw!the!vinyl!chloride!molecule.!!

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•! What!is!the!systematic!name!for!vinyl!chloride?!!

!!!!•! The!formation!of!PVC!is!similar!to!polyethylene!in!which!the!vinyl!chloride!

molecule!undergoes!an!addition!reaction!!!!

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• Identify!the!following!as!commercially!significant!monomers:!Y Vinyl!chloride!Y Styrene!!!By!both!their!systematic!and!common!names!

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•! The!systematic!name!for!PVC!is!________________________!!!

•! Pure!PVC!is!not!a!very!useful!plastic!as!it!is!hard!and!brittle!!!

Y! Additives!are!combined!with!PVC.!Explain!why.!!

!!!!•! Pure!PVC!is!not!a!very!useful!plastic!as!it!is!hard!and!brittle!!

!Y! Additives!are!combined!with!PVC.!Explain!why.!

!!!!!•! Non!–!volatile!plasticisers!can!be!added!to!PVC!to!adjust!its!rigidity!!!•! There!are!two!main!types!of!PVC.!For!each!provide!examples!of!their!uses.!!

!1.! Rigid!PVC!

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2.! Flexible!PVC!!!

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!•! PVC!is!also!known!as!a!thermoplastic.!Explain!what!this!means.!

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! Polystyrene!!!•! Styrene!is!the!common!name!given!to!a!monomer!that!make!up!polymers!

called!polystrene!!

•! Draw!the!styrene!molecule.!!

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•! What!is!the!systematic!name!for!styrene?!!

!!!!•! The!formation!of!polystrene!is!similar!to!polyethylene!in!which!the!styrene!

molecule!undergoes!an!addition!reaction!!!!

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!!!!!!!!!•! The!systematic!name!for!PVC!is!________________________!

!•! Polystyrenene!has!a!large!phenyl!side!group!which!is!large!and!bulky!

!Y! The!side!group!causes!strong!interaction!between!chains,!allowing!

polystyrene!to!be!_______________!and!__________________!



•! Polystyrene!is!very!stable!to!heat!and!UV!–!light.!Explain!why.!!!

!!!!!•! Due!to!the!minimal!branching!pure!polystyrene!is!quite!_____________________!and!

a!high!refractive!index.!This!allows!it!to!be!used!to!make!transparent!objects!including:!!Y! CD!cases!!Y! Disposable!drinking!cups!Y! Ornaments!!Y! Car!battery!cases!!!

!•! Polystyrene!can!be!also!be!softened!to!form!___________________.!Explain!how!this!

is!done.!!!!!!!!!!!!!!!!•! The!resulting!Styrofoam!is!used!to!make!drinking!cups,!foam!packing!material,!

containers!etc.!!

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Applications!4.1!!Question!1!!!a)! Draw!the!monomer!for!polyvinyl!chloride!!!!!!!!!!!!b)! Identify!the!systematic!name!for!the!monomer!of!polyvinyl!chloride.!

!!!!Question!2!!a)! Draw!the!monomer!for!polystyrene!

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b)! Identify!the!systematic!name!for!the!monomer!of!polystyrene.!!!

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Question!3!(NEAP!2002!–!Qu!23)!!The!physical!properties!of!polymers!are!determined!by!their!structure.!Explain!why!some!polymers!soften!upon!heating.!Name!one!polymer!which!behaves!this!way!and!describe!how!the!property!relates!to!its!use.!(4!marks)!!Student!Answer:!!!!!!!!!!!!!!!!!!!!!!!Sample!Answer:!!!!!!!!!!!!!



!!!!!!!Question!4!!Give!the!systematic!name!of!styrene.!Describe!two!uses!of!a!polymer!made!from!it!in!terms!of!its!properties.!(3!marks)!!!!!!!!!!!

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HSC Chemistry€¦ · HSC Chemistry Production of Materials ! Lesson!2:!!...

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