C9 Chemistry of the atmosphere

Question 1

What percentage of the Earth’s atmosphere is made of carbon dioxide gas?

Answer 1

0.04%

Question 2

What percentage of the Earth’s atmosphere is made of oxygen gas?

Answer 2

21%

Question 3

What percentage of the Earth’s atmosphere is made of argon gas?

Answer 3

0.9%

Question 4

What percentage of the Earth’s atmosphere is made of nitrogen gas?

Answer 4

78%

Question 5

For how long has the Earth’s atmosphere consisted of approximately 78% nitrogen, 21% oxygen, 0.9% argon and 0.04% carbon dioxide?

Answer 5

200 million years

Question 6

Approximately how old do scientists think the Earth is?

Answer 6

4.6 billion years

Question 7

One theory suggests that the first gases were released by volcanoes during the first billion years of the Earth’s existence. What gas was the most common gas at this time?

Answer 7

carbon dioxide

Question 8

What happened to water vapour in the atmosphere as the Earth cooled?

Answer 8

It condensed into seas and oceans

Question 9

Which planets’ atmospheres are thought to be similar today to the early Earth’s atmosphere?

Answer 9

Mars and Venus

Question 10

What effect did the early oceans and seas have on the level of carbon dioxide in the atmosphere?

Answer 10

The level of carbon dioxide in the atmosphere reduced as it was dissolved by the seas and oceans.

Question 11

Some of the carbon dioxide that dissolves into seas and oceans gets tied up in rocks, how does it get there?

Answer 11

Tiny sea creatures use carbon dioxide from the sea to form carbonates such as calcium carbonate in their shells. When they die these shells form layers at the bottom of the sea which become compressed into sedimentary rocks.

Question 12

Why did levels of oxygen in the atmosphere eventually start to rise?

Answer 12

Algae and green plants evolved and began to photosynthesise. This produced oxygen from carbon dioxide in the atmosphere.

Question 13

How long ago did algae begin to photosynthesise?

Answer 13

2.7 billion years ago

Question 14

How long did it take plants to release enough oxygen into the atmosphere to allow animals to evolve?

Answer 14

about 1 billion years (from 2.7 billions years ago to 1.7 billion years ago)

Question 15

How long ago did animals begin to evolve on Earth?

Answer 15

Approximately 1.7 billion years ago

Question 16

Apart from going into production of plant material by photosynthesis and into sedimentary rocks at the bottom of seas and oceans, where else did carbon dioxide get tied up?

Answer 16

In fossil fuels (coal, oil and natural gas).

Question 17

Name three greenhouse gases

Answer 17

Carbon dioxide, methane and water vapour

Question 18

How do greenhouse gases trap heat around the Earth?

Answer 18

Short wavelength infra-red radiation from the sun enter the atmosphere. They hit the Earth and warm it up. The Earth emits longer wavelength infra-red radiation which is trapped by greenhouse gases rather than radiating out into space.

Question 19

Why do many scientists believe that greenhouse gases are linked to climate change?

Answer 19

Peer-reviewed evidence (evidence provided by scientists and reviewed by other scientists to check how reliable their evidence is) suggests there is a direct link between levels of greenhouse gases in the atmosphere and the temperatures at the surface of the Earth which in turn have been linked to changes in the climate.

Question 20

Why is it that not all reports agree about the effect of greenhouse gases on climate change?

Answer 20

It is difficult to model such complex systems as global climate change. This leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.

Question 21

List four potential effects of climate change.

Answer 21

1. Loss of habitat - whether it is the polar ice-caps melting or the amazon rainforest drying up there are changes to the habitat of many species on Earth
2. Species being driven to extinction - if habitats are lost the animals that live in them may be driven to extinction
3. Flooding in some areas and drought in others - warm air holds more water than cold air and can change the pattern of rainfall across the globe
4. Oceans and seas cannot hold so much carbon dioxide gas when they are warmer so they will not be such good carbon sinks - leading to further climate change.

Question 22

What is a carbon footprint?

Answer 22

The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

Question 23

How can carbon footprints be reduced?

Answer 23

The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane.

Question 24

Name five atmospheric pollutants that can be released by burning fossil fuels.

Answer 24

1. carbon monoxide
2. nitrogen oxides
3. particulates (soot - carbon particles)
4. sufur dioxide
5. carbon dioxide

Question 25

What damaging effects can sulfur dioxide have?

Answer 25

It can cause acid rain and cause respiratory (breathing) problems for humans

Question 26

What damaging effects can carbon monoxide have?

Answer 26

It is a deadly, colourless (you can’t see it), odourless (you can’t taste it) toxic gas.

Question 27

What damaging effects can nitrogen oxides have?

Answer 27

They can cause acid rain and cause respiratory (breathing) problems for humans.

Question 28

What damaging effects can particulates have?

Answer 28

They can cause global dimming (reflecting some of the light energy from the sun) which can affect rainfall patterns.