Identify the monomer of a polymer whose repeat unit is –CH₂–CHCl–.

The monomer is chloroethene, CH₂=CHCl. The polymer is poly(chloroethene), known as PVC.

Why is polythene chemically inert?

Polythene is a saturated chain held together by strong, non-polar C–C and C–H bonds. Few reagents or microorganisms can attack these bonds, so polythene barely degrades.

Why does the inertness of polythene create a waste problem?

Polythene is not biodegradable and can persist in landfill or the sea for hundreds of years. Discarded polythene harms wildlife, which can swallow it or become entangled.

CCEA A-Level Life and Health Sciences 0008

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Organic Chemistry

Addition polymers, plastic waste and nylon

3 things to know
A2 2

Overview

Addition polymerisation of ethene and propene, monomers from repeat units, polythene waste, incineration and gas cleaning, recycling and cracking, biodegradable polymers, and nylon-6,6.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why must a monomer contain a C=C double bond to form an addition polymer?

Key term

Write an equation for the formation of poly(ethene) from ethene.

Key term

Write an equation for the formation of poly(propene) from propene.

Questions from this subtopic

Each one with the model answer underneath.

1
Why must a monomer contain a C=C double bond to form an addition polymer?
Model answer
The pi bond of the C=C double bond breaks, freeing electrons to form new single bonds to neighbouring monomers. The polymer is the only product.
2
Write an equation for the formation of poly(ethene) from ethene.
Model answer
The equation is n CH₂=CH₂ → –[CH₂–CH₂]ₙ–. Many ethene molecules join into one long saturated chain.
3
Write an equation for the formation of poly(propene) from propene.
Model answer
The equation is n CH₂=CHCH₃ → –[CH₂–CH(CH₃)]ₙ–. The poly(propene) chain carries a methyl group on every second carbon.
4
Identify the monomer of a polymer whose repeat unit is –CH₂–CHCl–.
Model answer
The monomer is chloroethene, CH₂=CHCl. The polymer is poly(chloroethene), known as PVC.
5
Why is polythene chemically inert?
Model answer
Polythene is a saturated chain held together by strong, non-polar C–C and C–H bonds. Few reagents or microorganisms can attack these bonds, so polythene barely degrades.
6
Why does the inertness of polythene create a waste problem?
Model answer
Polythene is not biodegradable and can persist in landfill or the sea for hundreds of years. Discarded polythene harms wildlife, which can swallow it or become entangled.

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