GCSE Chemistry revision

Atmospheric pollutants from fuels

Common atmospheric pollutants and their sources

AQA 4.9.3.1 Foundation & Higher

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Complete combustion occurs when a hydrocarbon burns in plenty of oxygen, producing only water and carbon dioxide whilst releasing energy.
Incomplete combustion happens when there is insufficient oxygen, producing harmful pollutants such as carbon monoxide and particulates (soot).

1. Complete vs Incomplete Combustion AQA

Complete combustion occurs when a hydrocarbon burns in plenty of oxygen, producing only water and carbon dioxide whilst releasing energy.
Incomplete combustion happens when there is insufficient oxygen, producing harmful pollutants such as carbon monoxide and particulates (soot).

Particulates are tiny solid particles of carbon produced during incomplete combustion of hydrocarbons.
When inhaled, particulates can become lodged in the lungs, causing damage and leading to respiratory problems.
Particulates can form dark clouds or smog that reflect sunlight back into space, reducing the amount of light reaching Earth — a phenomenon known as global dimming.

2. Particulates (Soot) AQA

Particulates are tiny solid particles of carbon produced during incomplete combustion of hydrocarbons.
When inhaled, particulates can become lodged in the lungs, causing damage and leading to respiratory problems.
Particulates can form dark clouds or smog that reflect sunlight back into space, reducing the amount of light reaching Earth — a phenomenon known as global dimming.

Carbon monoxide is a toxic gas produced during incomplete combustion when there is limited oxygen available.
When inhaled, carbon monoxide diffuses into the blood and binds to haemoglobin at the same site as oxygen, reducing the blood's ability to transport oxygen around the body.
In severe cases, carbon monoxide poisoning can lead to fainting, coma, or even death as the brain becomes starved of oxygen.
Carbon monoxide is particularly dangerous because it is both colourless and odourless, making it very difficult to detect.

3. Carbon Monoxide AQA

Carbon monoxide is a toxic gas produced during incomplete combustion when there is limited oxygen available.
When inhaled, carbon monoxide diffuses into the blood and binds to haemoglobin at the same site as oxygen, reducing the blood's ability to transport oxygen around the body.
In severe cases, carbon monoxide poisoning can lead to fainting, coma, or even death as the brain becomes starved of oxygen.
Carbon monoxide is particularly dangerous because it is both colourless and odourless, making it very difficult to detect.

Sulfur dioxide is produced when hydrocarbon fuels containing sulfur impurities are burned, causing the sulfur atoms to be oxidised to sulfur dioxide gas.
When sulfur dioxide dissolves in cloud water, it forms dilute sulfuric acid, which falls as acid rain.
Acid rain can corrode metals, damage buildings and statues, harm plants directly, and make soil more acidic, hindering plant growth.

4. Sulfur Dioxide AQA

Sulfur dioxide is produced when hydrocarbon fuels containing sulfur impurities are burned, causing the sulfur atoms to be oxidised to sulfur dioxide gas.
When sulfur dioxide dissolves in cloud water, it forms dilute sulfuric acid, which falls as acid rain.
Acid rain can corrode metals, damage buildings and statues, harm plants directly, and make soil more acidic, hindering plant growth.

Nitrogen oxides are formed when nitrogen and oxygen from the air react together at the very high temperatures reached inside internal combustion engines, such as those in cars.
Like sulfur dioxide, nitrogen oxides dissolve in cloud water to form dilute nitric acid, contributing to acid rain.
Breathing in nitrogen oxides can damage the lungs and cause respiratory problems.

5. Nitrogen Oxides AQA

Nitrogen oxides are formed when nitrogen and oxygen from the air react together at the very high temperatures reached inside internal combustion engines, such as those in cars.
Like sulfur dioxide, nitrogen oxides dissolve in cloud water to form dilute nitric acid, contributing to acid rain.
Breathing in nitrogen oxides can damage the lungs and cause respiratory problems.

Acid rain is formed when sulfur dioxide or nitrogen oxides dissolve in atmospheric moisture to produce dilute sulfuric acid or dilute nitric acid respectively.
Acid rain damages ecosystems by harming plants either through direct contact or by increasing soil acidity, making it harder for plants to absorb nutrients and grow.
Acid rain also causes significant damage to infrastructure by corroding metals and eroding certain building materials and stone statues.

6. Acid Rain: Causes and Effects AQA

Acid rain is formed when sulfur dioxide or nitrogen oxides dissolve in atmospheric moisture to produce dilute sulfuric acid or dilute nitric acid respectively.
Acid rain damages ecosystems by harming plants either through direct contact or by increasing soil acidity, making it harder for plants to absorb nutrients and grow.
Acid rain also causes significant damage to infrastructure by corroding metals and eroding certain building materials and stone statues.