Edexcel iGCSE Chemistry -4.13 Carbon Monoxide and Toxicity- Study Notes- New Syllabus
Edexcel iGCSE Chemistry -4.13 Carbon Monoxide and Toxicity- Study Notes- New syllabus
Edexcel iGCSE Chemistry -4.13 Carbon Monoxide and Toxicity- Study Notes -Edexcel iGCSE Chemistry – per latest Syllabus.
Key Concepts:
4.13 understand why carbon monoxide is poisonous, in terms of its effect on the capacity of blood to transport oxygen
(references to haemoglobin are not required)
4.13 Why Carbon Monoxide Is Poisonous
Carbon monoxide \( \mathrm{CO} \) is a poisonous gas.
It is produced by the incomplete combustion of hydrocarbons when oxygen supply is limited.
Key Idea
Carbon monoxide reduces the ability of the blood to carry oxygen.
As a result:
- Less oxygen reaches body cells.
- Cells cannot respire properly.
- Energy production decreases.
- Severe poisoning can cause unconsciousness or death.
Why This Is Dangerous
- Carbon monoxide is colourless.
- It is odourless.
- It cannot be detected easily without equipment.
- It can build up in enclosed spaces (e.g. faulty heaters).
Comparison of Oxygen and Carbon Monoxide
| Gas | Effect on Blood | Result |
|---|---|---|
| Oxygen \( \mathrm{O_2} \) | Enables transport to cells | Normal respiration |
| Carbon monoxide \( \mathrm{CO} \) | Reduces oxygen transport capacity | Cells starved of oxygen |
Exam Focus
You must explain poisoning in terms of:
- Reduced capacity of blood to transport oxygen.
- Less oxygen reaching body cells.
- Not enough oxygen for respiration.
Example 1 (Conceptual):
Why can carbon monoxide poisoning lead to unconsciousness?
▶️ Answer/Explanation
Carbon monoxide reduces the amount of oxygen transported by the blood.
Brain cells do not receive enough oxygen.
This can cause unconsciousness.
Example 2 (Application):
A faulty heater produces carbon monoxide in a poorly ventilated room. Explain why this is dangerous.
▶️ Answer/Explanation
Carbon monoxide builds up in the air.
It reduces the blood’s ability to carry oxygen.
Body cells do not receive enough oxygen.
This can be fatal.
Example 3 (Hard ):
Explain fully why carbon monoxide is described as a silent killer.
▶️ Answer/Explanation
Carbon monoxide is colourless and odourless.
It cannot be seen or smelled.
It is produced by incomplete combustion.
When inhaled, it reduces the blood’s ability to transport oxygen.
As a result, body cells receive insufficient oxygen for respiration.
This can lead to dizziness, unconsciousness and death.
Therefore it is called a silent killer.