Chemistry of the Atmosphere
What's covered
Key facts
Air Pollution
Carbon monoxide is a colourless pollutant that binds far more strongly than oxygen to haemoglobin, reducing oxygen transport.
Carbon Footprint
Carbon offsetting is paying for activities that absorb the same amount of CO₂ as you have emitted.
Composition of the Atmosphere
Argon makes up most (~0.93 %) of the remaining 1 % of air.
Greenhouse Gases and Climate Change
Carbon capture and storage (CCS) separates CO₂ from power-station flue gas and injects it into deep geological formations.
The Early Atmosphere
CO₂ was locked into rock as limestone (calcium carbonate from marine shells) and into fossil fuels (from photosynthesising plants and plankton that died and were buried).
Air Pollution
Carbon monoxide is produced by incomplete combustion of carbon-containing fuels when the oxygen supply is limited.
Carbon Footprint
Carbon capture and storage (CCS) can reduce industrial carbon footprints by trapping CO₂ before it reaches the atmosphere.
Composition of the Atmosphere
The proportion of carbon dioxide in today's atmosphere is less than 1 % (about 0.04 %).
Greenhouse Gases and Climate Change
Consequences of global warming include rising sea levels from melting polar ice and thermal expansion, and more frequent extreme weather events.
The Early Atmosphere
Two parallel processes reduced atmospheric CO₂: dissolution in oceans, and photosynthesis followed by burial of biomass.
Sample questions
A taste of the 46 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
How does sulfur dioxide (SO₂) form?
- ✓Burning sulfur-containing fuels; SO₂ dissolves in rain forming acid rain
- •From anaerobic respiration in waterlogged soils; causes photochemical smog
- •From N₂ + O₂ at high temperatures in engines; thins the ozone layer
- •From volcanoes only; absorbed by oceans before causing any damage
Why is carbon offsetting controversial?
- •Offsets are banned in the UK
- •Offsetting always costs too much
- ✓Reductions may not match emissions reliably
- •Trees absorb CO₂ very quickly
Which gas makes up most of the remaining 1% of air?
- ✓Argon
- •Helium
- •Krypton
- •Neon
Which gases are the main greenhouse gases?
- ✓Carbon dioxide, methane, water vapour
- •Hydrogen, helium, ozone
- •Nitrogen, oxygen, argon
- •Sulfur dioxide, ozone, krypton
How did CO₂ levels in the early atmosphere decrease?
- •Burned by early volcanic activity
- ✓Dissolved in oceans and locked into limestone
- •Escaped into outer space slowly
- •Reacted with nitrogen to form ammonia
Where do nitrogen oxide pollutants come from?
- •Burning of pure sulfur in air
- •Cooking food on gas hobs
- •Cooling of water in oceans
- ✓High temperatures in car engines
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