Explain disposal challenges for poly(alkene)s
Relate slow biological breakdown and harmful combustion products to the difficulty of disposing of poly(alkene)s.
Section 20 · Polymerisation
AS Level; Cambridge International Chemistry 9701, syllabus for 2028–2030. The taught examples are addition polymers of alkenes; do not generalise their disposal behaviour to every polymer. Written practice is self-checked
Before you begin
- Recognise C=C bonds and displayed, structural and repeat-unit formulae from Topics 13–14.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which disposal concern is specifically stated for poly(alkene)s?
What you will learn
- Recognise that poly(alkene)s are non-biodegradable
- Explain why this causes disposal difficulty
- Recognise that combustion may produce harmful products
Persistence makes disposal difficult
Poly(alkene)s such as poly(ethene) and poly(propene) are non-biodegradable in the syllabus context. They do not readily break down through biological processes, so discarded material can persist and accumulate if it is not managed.
Their persistence makes disposal and waste management difficult. Reuse and recycling can reduce some waste, but they depend on sorting, collection and suitable processing; they do not make every discarded item disappear.
Combustion has its own risks
Burning poly(alkene)s can produce harmful combustion products. The syllabus expects recognition of this difficulty, rather than a detailed toxicology list or an assumption that burning is a safe disposal method.
A complete evaluation should connect the polymer property to a consequence and a realistic limitation. Do not claim that all polymers have identical biodegradability or combustion products; this outcome specifically concerns poly(alkene)s.
Pause and explain
Why is combustion not a simple risk-free solution for poly(alkene) waste?
Worked example
Give two reasons why disposing of poly(alkene) waste can be difficult.
Show the worked solution
- Consider what happens to the material in the environment.
- Consider the products if it is burned.
- Connect each property to a disposal consequence.
Answer Poly(alkene)s are non-biodegradable, so they can persist and accumulate. Combustion may produce harmful products, so burning is not a risk-free solution.
Try a topic test
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Explain how non-biodegradability creates a waste-management problem for poly(ethene).
Give me a hint
Link resistance to biological breakdown with persistence after disposal.
Compare my reasoning
- Poly(ethene) is a poly(alkene).
- It is non-biodegradable in the syllabus context.
- Persistent waste can accumulate if not collected and managed.
Because poly(ethene) is non-biodegradable, it can persist in the environment and accumulate, creating a long-term disposal problem.
Look for these in your work
- Correct polymer class
- Property stated
- Environmental consequence linked
A proposal is to burn all discarded PVC. Give a syllabus-based reason this is not automatically a safe solution.
Give me a hint
Consider the stated combustion concern, not only the reduction in volume.
Compare my reasoning
- Combustion may produce harmful products.
- Reducing visible waste does not remove the hazard.
- State the limitation without claiming all polymers burn identically.
Burning can produce harmful combustion products, so it is not automatically a safe disposal method. The exact risk depends on the materials and conditions.
Look for these in your work
- Hazard identified
- Proposal evaluated
- Claim appropriately limited
Compare recycling and disposal by burning for poly(alkene) waste, giving one limitation of each approach.
Give me a hint
Use the two syllabus difficulties and avoid presenting either option as universally complete.
Compare my reasoning
- Recycling depends on collection and sorting.
- Burning may produce harmful products.
- Relate both to the need for managed disposal.
Recycling can recover material but depends on effective collection, sorting and processing. Burning may reduce waste volume but can produce harmful combustion products. Neither option removes the need for appropriate waste management.
Look for these in your work
- Both approaches addressed
- One limitation each
- Balanced conclusion
Common mistakes
- Calling all plastics biodegradable
- Treating burning as harmless
- Naming recycling without explaining its limitations
- Claiming every polymer has the same disposal behaviour
What can you explain now?
Which disposal concern is specifically stated for poly(alkene)s?
Compare with the explanation
They are non-biodegradable
Their persistence makes disposal difficult.
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Make it stick
Which two syllabus properties make poly(alkene) disposal difficult, and what consequence follows from each?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.