3.3.7Organic Chemistry
Waste Polymers — Edexcel AS Chemistry Revision Notes & Topical Questions
5 min read 4 parts Lesson 30 of 42
Section 1 of 4Why Polymers Persist
Strong bonds
- Addition polymers contain strong, non-polar C–C and C–H bonds that are not easily broken.
No attraction
- Water, acids and microorganisms cannot attack the non-polar chains, so they are not biodegradable.
Volume
- Large quantities of plastic waste are produced, much of it from single-use packaging.
Pollution
- Discarded plastic can persist for centuries and harm wildlife, especially in the oceans.
Raw material
- Most polymers come from crude oil, a finite resource that is also used as fuel.
Section 2 of 4Disposal Methods
Disposal Methods
Landfill
- Burying waste is cheap and simple but takes up land, and the plastic does not break down.
Incineration
- Burning waste releases energy that can generate electricity, but it produces CO₂.
Toxic gases
- Burning some polymers gives harmful gases, such as hydrogen chloride from PVC, which must be removed by scrubbing.
Recycling
- Sorted polymers are melted and remoulded, saving raw material and energy.
Feedstock
- Polymers can be cracked into small molecules that are used to make new plastics.
| Method | Advantage | Disadvantage |
|---|---|---|
| Landfill | Cheap and easy | Uses land; polymer persists |
| Incineration | Gives usable energy | Releases CO₂ and possibly toxic gases |
| Recycling | Saves crude oil and energy | Needs sorting; quality can fall |
Section 3 of 4Reducing the Problem
1
Reducing use and reusing items in the first place cuts the amount of waste that has to be treated.
2
Collecting and sorting waste by polymer type is needed before it can be melted and reused.
3
Mixed or contaminated plastics are harder to recycle and may be cracked or incinerated instead.
4
Biodegradable polymers made from plant starch can be broken down by microorganisms.
5
Photodegradable polymers contain additives that make them weaken in sunlight, though they leave fragments behind.
Section 4 of 4Exam Checklist & Tips
3.3.7 – Key Points for the Exam
- Biodegradable Able to be broken down by microorganisms.
- Incineration Burning waste at high temperature.
- Recycling Reprocessing waste so that it can be used again.
- Feedstock recycling Breaking down polymers into monomers or other chemicals for reuse.
- Landfill Disposal of waste by burying it in the ground.
Common Mistakes
- Saying addition polymers are biodegradable because they are made from organic compounds.
- Forgetting that incineration of PVC produces toxic hydrogen chloride that must be removed.
- Describing recycling as having no costcollection, sorting and processing need energy.
- Giving only the advantages of one method and not weighing up advantages and disadvantages.
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