Edexcel iGCSE Chemistry -4.47 Disposal of Addition Polymers- Study Notes- New Syllabus
Edexcel iGCSE Chemistry -4.47 Disposal of Addition Polymers- Study Notes- New syllabus
Edexcel iGCSE Chemistry -4.47 Disposal of Addition Polymers- Study Notes -Edexcel iGCSE Chemistry – per latest Syllabus.
Key Concepts:
4.47 explain problems in the disposal of addition polymers, including:
• their inertness and inability to biodegrade
• the production of toxic gases when they are burned
4.47 Problems in the Disposal of Addition Polymers
Addition polymers (such as poly(ethene) and poly(chloroethene)) are widely used plastics.
However, they cause environmental problems when disposed of.
1. Inertness and Non-Biodegradability
Addition polymers are chemically inert.
- They are unreactive.
- They do not easily break down.
- Microorganisms cannot digest them.
This means they are non-biodegradable.
As a result:
- They accumulate in landfill sites.
- They remain in the environment for many years.
- They contribute to plastic pollution.
Their long carbon chains and strong covalent bonds make them very stable.
2. Production of Toxic Gases When Burned
Some plastics release harmful gases when burned.
For example, poly(chloroethene) (PVC) contains chlorine.
When burned, it can produce hydrogen chloride gas:
\( \mathrm{HCl} \)
Hydrogen chloride is:
- Toxic.
- Corrosive.
- Contributes to air pollution.
Incomplete combustion of plastics can also produce:
\( \mathrm{CO} \) (carbon monoxide)
Carbon monoxide is poisonous.
| Problem | Reason | Consequence |
|---|---|---|
| Non-biodegradable | Strong covalent bonds | Build up in landfill |
| Burning releases toxic gases | Contains elements such as chlorine | Air pollution |
Why These Problems Occur
- Addition polymers have very stable carbon–carbon backbones.
- Microorganisms cannot break these long chains.
- Some polymers contain other elements (e.g. chlorine).
- Burning can form acidic or poisonous gases.
Key Points
- Addition polymers are inert and non-biodegradable.
- They accumulate in landfill.
- Burning some polymers produces toxic gases.
- Examples include hydrogen chloride and carbon monoxide.
Example 1 (Conceptual):
Why do addition polymers not biodegrade easily?
▶️ Answer/Explanation
They are chemically inert.
They have strong covalent bonds in long carbon chains.
Microorganisms cannot break them down.
Example 2 (Application):
State one harmful gas that may be produced when PVC is burned.
▶️ Answer/Explanation
\( \mathrm{HCl} \) (hydrogen chloride).
Example 3 (Hard):
Explain fully two environmental problems caused by the disposal of addition polymers.
▶️ Answer/Explanation
Addition polymers are inert and non-biodegradable.
They do not break down naturally.
They accumulate in landfill sites and cause long-term pollution.
When some polymers are burned, toxic gases such as hydrogen chloride or carbon monoxide can be produced.
These gases cause air pollution and can be harmful to health.