Chemistry of The Atmosphere Questions P2

What is the current composition of Earth’s atmosphere?

Approximately 78% nitrogen, 21% oxygen, and 1% other gases (including carbon dioxide, water vapour, and noble gases).

How has the Earth's atmosphere changed over time?

It changed from mostly carbon dioxide with little or no oxygen to an atmosphere rich in nitrogen and oxygen.

What were the main gases in Earth’s early atmosphere?

Likely carbon dioxide, water vapour, methane, and ammonia – similar to those released by volcanoes today.

What caused water vapour in the early atmosphere?

Volcanic eruptions released water vapour into the air.

How did oceans form on early Earth?

As Earth cooled, water vapour condensed and formed oceans.

How was carbon dioxide removed from the early atmosphere?

Dissolved in oceans, forming carbonates; used by photosynthesising organisms; locked in fossil fuels and sedimentary rocks.

How did photosynthesis help change the atmosphere?

Plants and algae absorbed carbon dioxide and released oxygen.

What organisms first carried out photosynthesis?

Algae and simple plants.

How did oxygen levels increase in the atmosphere?

Through photosynthesis by algae and plants over millions of years.

What happened to carbon once it was removed from the atmosphere?

It became locked in fossil fuels and sedimentary rocks like limestone.

What is a greenhouse gas?

A gas that absorbs infrared radiation and helps keep Earth warm.

Name three greenhouse gases.

Carbon dioxide, methane, water vapour.

How do greenhouse gases cause the greenhouse effect?

They absorb heat radiated from the Earth’s surface and re-radiate it in all directions, warming the atmosphere.

What is the greenhouse effect essential for?

Maintaining temperatures high enough to support life.

What is climate change?

Long-term changes in Earth’s temperature and weather patterns due to increased greenhouse gases.

What human activities increase carbon dioxide levels?

Burning fossil fuels, deforestation.

What human activities increase methane levels?

Animal farming, decomposition in landfills, rice farming.

What are the potential effects of climate change?

Melting ice caps, sea level rise, more extreme weather, habitat loss, changes in rainfall and food production.

Why is climate change difficult to fully understand?

It is complex, and predictions are based on models with varying assumptions.

What are carbon footprints?

The total amount of carbon dioxide and other greenhouse gases emitted over a product’s or person’s lifetime.

How can carbon footprints be reduced?

Use renewable energy, improve energy efficiency, reduce waste, eat less meat, carbon capture.

What are the problems with reducing carbon footprints?

Cost, lifestyle changes, lack of public education or political will.

What are atmospheric pollutants?

Harmful substances released into the air, often from combustion.

What gases are released when fossil fuels are burned?

Carbon dioxide, carbon monoxide, sulfur dioxide, oxides of nitrogen, and particulates.

What causes carbon monoxide?

Incomplete combustion of fuels.

Why is carbon monoxide dangerous?

It is toxic and binds to haemoglobin, reducing oxygen transport in the blood.

What causes sulfur dioxide?

Sulfur impurities in fuels reacting with oxygen when burned.

What are the effects of sulfur dioxide?

It causes acid rain and respiratory problems.

What causes oxides of nitrogen?

Reaction between nitrogen and oxygen in air at high temperatures in car engines.

What are the effects of nitrogen oxides?

They cause acid rain and respiratory issues.

What are particulates?

Tiny solid particles (often carbon) released from burning fuels.

What are the effects of particulates?

They cause health problems (e.g. lung damage) and global dimming.

What is acid rain?

Rainwater that contains dissolved sulfur dioxide or nitrogen oxides, making it acidic.

What are the impacts of acid rain?

Damage to plants, soil, aquatic life, and corrosion of buildings/statues.

What is global dimming?

Reduction of sunlight reaching Earth's surface due to particulates reflecting sunlight.

What is meant by complete combustion?

When a fuel burns fully in excess oxygen, producing carbon dioxide and water.

What is meant by incomplete combustion?

When a fuel burns in limited oxygen, producing carbon monoxide and/or carbon (soot).

What is the word equation for complete combustion of methane?

Methane + oxygen → carbon dioxide + water

What is the word equation for incomplete combustion of methane?

Methane + oxygen → carbon monoxide + water (or) carbon + water

What actions can reduce air pollution from combustion?

Use cleaner fuels, catalytic converters, electric vehicles, public transport.

Is climate change the same as ozone depletion?

No – climate change involves greenhouse gases; ozone depletion involves CFCs damaging the ozone layer.