GCSE Chemistry revision

Properties and effects of atmospheric pollutants

Common atmospheric pollutants and their sources

AQA 4.9.3.2 Foundation & Higher

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Carbon monoxide is a colourless, odourless, toxic gas that binds irreversibly to haemoglobin in red blood cells, drastically reducing their capacity to transport oxygen around the body and potentially causing suffocation.
Example: Incomplete combustion of methane in poorly ventilated or faulty home gas boilers produces carbon monoxide, creating a severe indoor poisoning hazard.

1. Toxicity of Carbon Monoxide AQA

Carbon monoxide is a colourless, odourless, toxic gas that binds irreversibly to haemoglobin in red blood cells, drastically reducing their capacity to transport oxygen around the body and potentially causing suffocation.
Example: Incomplete combustion of methane in poorly ventilated or faulty home gas boilers produces carbon monoxide, creating a severe indoor poisoning hazard.

Incompletely combusted fuel releases unburnt hydrocarbons into the atmosphere, which react with sunlight and other pollutants to form ground-level ozone and photochemical smog.
Example: Traffic exhaust emissions in heavily populated cities release unburnt fuel molecules that contribute to toxic urban smog, causing eye irritation and respiratory discomfort.

2. Unburnt Hydrocarbons and Smog AQA

Incompletely combusted fuel releases unburnt hydrocarbons into the atmosphere, which react with sunlight and other pollutants to form ground-level ozone and photochemical smog.
Example: Traffic exhaust emissions in heavily populated cities release unburnt fuel molecules that contribute to toxic urban smog, causing eye irritation and respiratory discomfort.

Sulfur dioxide (formed when sulfur impurities in fossil fuels burn) and oxides of nitrogen (formed when high temperatures in engines cause atmospheric nitrogen and oxygen to react) dissolve in clouds to form acid rain.
Example: Coal-fired power stations burning sulfur-rich fuel release sulfur dioxide gas, which reacts with water vapour in clouds to form dilute sulfuric acid.

3. Formation of Acidic Gases AQA

Sulfur dioxide (formed when sulfur impurities in fossil fuels burn) and oxides of nitrogen (formed when high temperatures in engines cause atmospheric nitrogen and oxygen to react) dissolve in clouds to form acid rain.
Example: Coal-fired power stations burning sulfur-rich fuel release sulfur dioxide gas, which reacts with water vapour in clouds to form dilute sulfuric acid.

Acid rain acidifies lakes and rivers (killing fish and aquatic life), strips nutrients from forest soils, damages leaf cuticles, and corrodes limestone buildings and metal structures.
Example: Acid rain accelerates the weathering of ancient limestone monuments and statues by reacting with calcium carbonate to form soluble calcium salts.

4. Environmental Impact of Acid Rain AQA

Acid rain acidifies lakes and rivers (killing fish and aquatic life), strips nutrients from forest soils, damages leaf cuticles, and corrodes limestone buildings and metal structures.
Example: Acid rain accelerates the weathering of ancient limestone monuments and statues by reacting with calcium carbonate to form soluble calcium salts.

Incomplete combustion produces solid particulates (soot and unburnt carbon) that, when inhaled, travel deep into the lungs, irritating airways and worsening conditions like asthma and heart disease.
Example: Inhaling fine particulate matter (PM2.5) from older diesel engines aggravates lung tissue and increases the risk of chronic respiratory diseases.

5. Respiratory Damage from Particulates AQA

Incomplete combustion produces solid particulates (soot and unburnt carbon) that, when inhaled, travel deep into the lungs, irritating airways and worsening conditions like asthma and heart disease.
Example: Inhaling fine particulate matter (PM2.5) from older diesel engines aggravates lung tissue and increases the risk of chronic respiratory diseases.

Suspended particulate matter in the upper atmosphere reflects incoming sunlight back into space, reducing the total amount of light reaching Earth's surface—a phenomenon known as global dimming.
Example: Large industrial soot emissions form atmospheric clouds that reflect solar radiation, decreasing ground-level sunlight and potentially altering global rainfall patterns.

6. Global Dimming AQA

Suspended particulate matter in the upper atmosphere reflects incoming sunlight back into space, reducing the total amount of light reaching Earth's surface—a phenomenon known as global dimming.
Example: Large industrial soot emissions form atmospheric clouds that reflect solar radiation, decreasing ground-level sunlight and potentially altering global rainfall patterns.