AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Properties and effects of atmospheric pollutants: Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
Sulfur dioxide (SO₂) and oxides of nitrogen (NOₓ, such as NO and NO₂) are atmospheric pollutants released mainly by burning fossil fuels.
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Sulfur dioxide (SO₂) and oxides of nitrogen (NOₓ, such as NO and NO₂) are atmospheric pollutants released mainly by burning fossil fuels. Sulfur dioxide forms when sulfur impurities in coal or oil burn; oxides of nitrogen form when the high temperature inside engines makes nitrogen and oxygen from the air react. Both gases are harmful to humans because they irritate the airways, triggering coughing, wheezing and worsening asthma or other respiratory problems. They also dissolve in atmospheric water and are oxidised, producing acidic solutions that fall as acid rain. Acid rain lowers the pH of lakes and soils, damaging plants, fish and buildings. Reducing these emissions uses catalytic converters, flue-gas desulfurisation and cleaner fuels.
What earns the marks
- Sulfur dioxide is produced when fossil fuels containing sulfur impurities are burned, for example in coal-fired power stations.
- Oxides of nitrogen form when nitrogen and oxygen from the air react at the high temperatures found in vehicle engines.
- Acid rain can damage plants, kill fish in lakes and corrode stone buildings; reducing emissions uses catalytic converters and flue-gas desulfurisation.
Common mistakes and how to put them right
Saying that oxides of nitrogen come from nitrogen in the fuel.
Put it right: They form when nitrogen and oxygen in the air react at high engine temperatures.
Confusing the gases that cause acid rain with carbon dioxide.
Put it right: Sulfur dioxide and oxides of nitrogen are the named acidic pollutants, although carbon dioxide also forms a weak acid in water.
Stating that acid rain directly poisons humans.
Put it right: The direct human effect is respiratory irritation, while acid rain mainly harms ecosystems and buildings.
Exam tips
- Name both pollutant gases and give a separate source for each rather than treating them as one gas.
- Link each gas to both effects in the statement: human respiratory problems and acid rain.
- Use the term oxides of nitrogen or NOₓ and refer to sulfur dioxide as SO₂ to show precise chemical vocabulary.
Try the lesson
The start of the Properties and effects of atmospheric pollutants: Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain. lesson, made from checked teaching notes for this specification point.
Have a go first
Which two gases are described as causing respiratory problems in humans and acid rain?
Listen
Sulfur dioxide (SO₂) and oxides of nitrogen (NOₓ, such as NO and NO₂) are atmospheric pollutants released mainly by burning fossil fuels. Sulfur dioxide forms when sulfur impurities in coal or oil burn; oxides of nitrogen form when the high temperature inside engines makes nitrogen and oxygen from the air react. Both gases are harmful to humans because they irritate the airways, triggering coughing, wheezing and worsening asthma or other respiratory problems. They also dissolve in atmospheric water and are oxidised, producing acidic solutions that fall as acid rain. Acid rain lowers the pH of lakes and soils, damaging plants, fish and buildings. Reducing these emissions uses catalytic converters, flue-gas desulfurisation and cleaner fuels. A strong answer earns marks for these points. Sulfur dioxide is produced when fossil fuels containing sulfur impurities are burned, for example in coal-fired power stations. Oxides of nitrogen form when nitrogen and oxygen from the air react at the high temperatures found in vehicle engines. Acid rain can damage plants, kill fish in lakes and corrode stone buildings; reducing emissions uses catalytic converters and flue-gas desulfurisation. A common slip: Saying that oxides of nitrogen come from nitrogen in the fuel. Instead, they form when nitrogen and oxygen in the air react at high engine temperatures. Exam tip: Name both pollutant gases and give a separate source for each rather than treating them as one gas.
Key words
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Atmospheric pollution
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Combustion of fossil fuels
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Human health effects
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Acid deposition and environmental damage
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See every definition
- Atmospheric pollution
- Sulfur dioxide and oxides of nitrogen are atmospheric pollutants released mainly by burning fossil fuels.
- Combustion of fossil fuels
- Sulfur dioxide forms when sulfur impurities in coal or oil burn, and oxides of nitrogen form when nitrogen and oxygen from the air react at the high temperatures inside engines.
- Human health effects
- Both gases irritate the airways, triggering coughing, wheezing and worsening asthma or other respiratory problems.
- Acid deposition and environmental damage
- The gases dissolve in atmospheric water and are oxidised, producing acidic solutions that fall as acid rain, lowering the pH of lakes and soils and damaging plants, fish and buildings.
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