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GCSE Chemistry · key term
A group of compounds containing nitrogen and oxygen, often represented as NOₓ, which form when nitrogen and oxygen react at high temperatures.
Used by AQA, Edexcel and OCR
Specification 4.9.3.1 · Paper 2
A general name for several compounds of nitrogen and oxygen, often written as NOₓ.
Revise: Pollutants from CombustionVery high-temperature combustion in air can produce oxides of nitrogen from atmospheric nitrogen and oxygen.
Specification 8.13 · Paper 2
Gases containing nitrogen chemically combined with oxygen, formed when nitrogen and oxygen react at high temperatures; they are often represented collectively as .
Revise: Oxides of NitrogenOxides of nitrogen escape in exhaust gases and contribute to air pollution. They can irritate the respiratory system and cause breathing problems. They can also dissolve and react in rainwater, contributing to acid rain.
Specification C6.3f · Paper 2 (Foundation), Paper 4 (Higher)
A group of gases, including nitrogen monoxide and nitrogen dioxide, formed when nitrogen and oxygen react at high temperatures.
Revise: Atmospheric PollutantsAt the high temperatures reached during combustion, nitrogen and oxygen from the air can react to form oxides of nitrogen. These are different routes to air pollution, even when the emissions come from the same exhaust or chimney.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Pollutants from combustionOxides of nitrogen reveal that air has been heated sufficiently for its nitrogen and oxygen to react, followed by further oxidation in the atmosphere. Identifying the correct route means looking for the relevant condition: limited oxygen, sulfur in the fuel, or very high temperature.
Link each pollutant to its specific cause: limited oxygen → carbon monoxide and soot; sulfur in the fuel → sulfur dioxide; high temperature in air → oxides of nitrogen.
State that the nitrogen and oxygen come from the air; oxides of nitrogen are not produced simply because the fuel contains nitrogen.
Link the cause and effect clearly: the engine's high temperature allows nitrogen and oxygen to react, producing oxides of nitrogen.
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