ChemistryChapter 13: Environmental Chemistry-Air
Air Pollutants (named)
An air pollutant is a substance present in the atmosphere at a concentration that can harm human health, living organisms, materials or the
Definition
An air pollutant is a substance present in the atmosphere at a concentration that can harm human health, living organisms, materials or the environment.
Core Concept
Air pollution is not caused by one single chemical. Different pollutants have different sources, chemical properties, atmospheric reactions, health effects, and environmental effects. Important pollutants include CO, SO₂, NOₓ, O₃, and particulate matter. A useful idea is: Source → Pollutant → Atmospheric chemistry → Effect.
Beginner
Air pollutants are harmful substances in the air. Examples include CO, SO₂, NO₂, smoke and tiny particles. Different pollutants come from different sources.
Intermediate
Air pollutants can be divided into primary and secondary pollutants. CO and SO₂ are examples commonly emitted directly. Ground-level ozone is commonly formed later through atmospheric reactions and is therefore a secondary pollutant.
Advanced
The environmental effect of a pollutant depends on more than its identity. Important factors include concentration, atmospheric lifetime, chemical reactivity, exposure duration, meteorological conditions, and secondary reactions. Thus even a trace gas can be environmentally important.
Important Formula / Equation
Incomplete combustion: 2C + O₂ → 2CO Sulphur combustion: S + O₂ → SO₂ High-temperature NO formation: N₂ + O₂ → 2NO
Remember / Key Reminder
CO → incomplete combustion. SO₂ → sulphur-containing fuel. NOₓ → high-temperature combustion. Particulates = tiny suspended particles. Ground-level O₃ = pollutant. Primary pollutant = emitted directly. Secondary pollutant = formed in the atmosphere.
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Air Pollutants (named)
Sticky Notes · Quick Revision
Memory Point 1
- CO → incomplete combustion
Memory Point 2
- CO toxic
Memory Point 3
- SO₂ → acid deposition
Memory Point 4
- NOₓ → smog chemistry
Memory Point 5
- PM = particulate matter
Memory Point 6
- Ground O₃ = pollutant
Memory Point 7
- Primary = emitted
Memory Point 8
- Secondary = formed later
60-second revision
- Air pollution includes harmful gases and particles such as CO, SO₂, NOₓ, particulate matter and ground-level ozone. Some pollutants are emitted directly, while others form through atmospheric chemical reactions.
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