GCSE Chemistry - Chapter 13: The Earth's Atmosphere (AQA)

What is meant by the term 'atmosphere'?

Mixture of gases surrounding a planet

When do scientists think the Earth was formed?

4.6 billion years ago

What edvidence can scientists use to reconstruct a picture of the early atmosphere?

Gas bubbles in ancient rocks, atmospheres of other planets

What released most of the gases into the early atmosphere?

Volcanoes

What main gases made up the early atmosphere?

Carbon dioxide, water vapour, nitrogen

What other gases were present in small amounts in the early atmosphere?

Methane, ammonia

How were oceans formed?

Water vapour in the early atmosphere condensed

How much of the early atmosphere was carbon dioxide?

~95%

How did oxygen levels increase in the Earth's early atmosphere?

Photosynthesis of algae

How did carbon dioxide levels decrease in the Earth's early atmosphere?

Photosynthesis, dissolving in oceans, forming sedimentary rocks and fossil fuels

How did nitrogen build up in the atmosphere?

From volcanes

How was methane and ammonia removed from the atmosphere?

They reacted with oxygen

What are the main gases in the atmosphere today?

Nitrogen and oxygen

Roughly, how much nitrogen is in the modern atmosphere?

~80%

Roughly, how much oxygen is in the modern atmosphere?

~20%

What other gases make up the modern atmosphere in small amounts?

Carbon dioxide, argon, noble gases

What are greenhouse gases?

Gases that absorb infared radiation

What are the main greenhouse gases?

Carbon dioxide, water vapor, methane

What is the greenhouse effect?

The process by which gases hold heat in the atmosphere

How does the greenhouse effect work?

When the Sun heats up the Earth, some of that energy escapes into space. Greenhouse gases absorb some of that heat, warming the Earth

Why is the greenhouse effect important?

Maintains global temperatures high enough for life

Why are carbon dioxide levels increasing within the atmosphere?

Fossil fuel usage, deforestation

Why are methane levels increasing within the atmosphere?

Rice farming, cattle farming

What is some of the edvidence of global warming?

Ice cores, tree rings

What are some of the consequences of rising levels of greenhouse gases?

Rising sea levels, extreme weather events, changes in temperature and rainfall

Why are sea levels rising?

Melting polar ice caps, expansion of warmer oceans

What is a carbon footprint?

Total amount of greenhouse gases emitted over the life cycle of a product, service or event

What are some solutions to climate change?

Carbon capture and storage, reducing the demand for beef, taxing fossil fuels, using biofuels

How can the carbon footprint be reduced?

By reducing emissions of carbon dioxide and methane

What are some problems of reducing a carbon footprint?

Cost, unwillingness to change

What are the products of complete combustion?

Carbon dioxide and water

What are the products of incomplete combustion?

Carbon monoxide, carbon, water

Why is carbon monoxide dangerous/toxic?

Colourless and odourless

What can large amounts of particulate carbon lead to?

Global dimming

What are the main two problems caused by particulates? (humans)

Asthma and breathing difficulties

What are atmospheric pollutants?

Products of the burning of fuel

What are some pollutants?

Carbon dioxide, carbon monoxide, carbon (soot), sulfur dioxide, oxides of nitrogen

What can sulphur dioxide/oxides of nitrogen cause?

Acid rain

What causes sulfur dioxide to be released into the air?

Burning of fossil fuels

What causes oxides of nitrogen to be released into the air?

Car engines

What are the effects of acid rain?

Acidification of lakes and soil, weathering of limestone