Chapter 13 The Earth's Atmosphere

Question 1

How could you describe the Earth’s atmosphere for the last 200 million years?

Answer 1

For the last 200 million years the proportions of gases in the Earth’s atmosphere have remained constant.

Question 2

Name the 3 main gases in the air and what % of the air is made up of each. What makes up the rest of the air?

Answer 2

The Earth’s atmosphere is 78% Nitrogen, 21% Oxygen and 0.04% carbon dioxide with the water vapour, hydrogen, methane and some noble gases making up the rest in very small quantities.

Question 3

When is the Earth thought to have formed?

Answer 3

The Earth is thought to have formed 4.6 billion years ago.

Question 4

Do we know for sure what the atmosphere was like when the Earth first formed?

Answer 4

It is difficult to know for sure what the atmosphere was like so long ago but there are theories.

Question 5

What planets in our solar system currently have atmospheres that may resemble that of early Earth?

Answer 5

It is likely that the Earth’s atmosphere started out much like the atmospheres of Mars and Venus today.

Question 6

What are the atmospheres of Mars and Venus mostly composed of?

Answer 6

The atmospheres of Mars and Venus today are mostly composed of carbon dioxide with very little oxygen. Earth once likely had a similar atmosphere.

Question 7

What is the most likely theory about the surface of early Earth?

Answer 7

The most likely theory is that early Earth was covered in volcanoes.

Question 8

What 4 gases are produced by volcanoes?

Answer 8

Volcanoes produced water vapour, carbon dioxide, nitrogen and methane. The concentrations of these gases in the atmosphere increased.

Question 9

Where did the Earth’s oceans come from?

Answer 9

Water vapour from the volcanoes condensed to form the Earth’s oceans.

Question 10

What happens when carbon dioxide dissolves in water?

Answer 10

Carbon dioxide from the air dissolved in the water to make carbonic acid.

Question 11

What does carbonic acid get converted into and where does this go? What effect will this have on carbon dioxide concentration in the air.

Answer 11

Carbonic acid was converted into solid carbonates that settled to the bottom of the oceans and produced sediment. This reduced the carbon dioxide concentration in the atmosphere.

Question 12

When did photosynthetic algae and plants evolve and become established?

Answer 12

Photosynthetic algae and plants evolved and became established 2.5 billion years ago.

Question 13

What impact do algae and plants have on the concentration of gases in the air?

Answer 13

Algae and plants take carbon dioxide out of the air and add oxygen to the air.

Question 14

What is the equation for photosynthesis?

Answer 14

The equation for photosynthesis is:

Question 15

What gas is responsible for the evolution of life on Earth.

Answer 15

The evolution of life on Earth as we know it was only possible due to the increase in oxygen levels.

Question 16

How do fossil fuels form?

Answer 16

As plants and animals die and fall to the bottom of the oceans, the carbon in them gets trapped and eventually forms fossil fuels.

Question 17

How was methane and ammonia removed from the air?

Answer 17

Any methane and ammonia that was in the air was removed once oxygen concentration increased as they reacted with oxygen.

Question 18

Why are greenhouse gases important?

Answer 18

Greenhouse gases maintain the temperatures on Earth high enough to support life. Without the greenhouse effect the Earth would be too cold to support most living organisms.

Question 19

What are the 3 main greenhouse gases? Name 3 other greenhouse gases.

Answer 19

The main greenhouse gases are carbon dioxide, water vapour and methane. CFCs, ozone and nitrous oxide are also greenhouse gases.

Question 20

Describe the process by which the greenhouse effect leads to the warming of the Earth. (5 steps).

Answer 20

The greenhouse effect occurs because:

1. Electromagnetic radiation at long and short wavelengths is produced by the sun and and passes through the sun’s atmosphere.
2. The Earth absorbs the short wave radiation and warms up. The long wave radiation is radiated from the Earth as infrared radiation.
3. Some of the longwave infrared radiation is absorbed by greenhouse gases in the atmosphere instead of radiating away from the earth.
4. The greenhouse gases radiate the heat energy in all directions including back to Earth.
5. The atmosphere warms up leading to the greenhouse effect.

Question 21

What impact have human activities had on concentrations of carbon dioxide and methane in the atmosphere?

Answer 21

Human activities have increased the concentrations of carbon dioxide and methane in the atmosphere.

Question 22

Give 3 human activities that produce greenhouse gases and state which gases they produce.

Answer 22

Human activities that produce greenhouse gases include:
1. Burning fossil fuels (for heat, electricity, industry and transport) which produced carbon dioxide.

2. Raising livestock which produced methane.
3. Decay of organic waste in landfill sites which produced methane.

Question 23

What are the 2 most effective ways to reduce greenhouse gases in the atmosphere?

Answer 23

The most effective ways to reduce greenhouse gases in the atmosphere are to reduce energy consumption and reduce the use of fossil fuels.

Question 24

What has global warming over the last 200 years has resulted in?

Answer 24

Global warming over the last 200 years has resulted in an overall increase in average surface temperatures.

Question 25

What does ‘peer reviewed’ mean?

Answer 25

When scientists conduct research it is peer reviewed before it is published. This means that other scientists, qualified in the same area of expertise, have read, evaluated and approved the research for publication as factually correct.

Question 26

Based on peer-reviewed evidence on climate change, what do most scientists agree on?

Answer 26

Based on peer-reviewed evidence on climate change most scientists agree that human activities are responsible for the global warming we are currently experiencing.

Question 27

What does Global Warming lead to?

Answer 27

Global warming can lead to global climate change.

Question 28

Why is modelling the effect of global warming on global climate change very difficult?

Answer 28

Modelling the effect of global warming on global climate change is very difficult to do due to the complexity of weather systems. This makes accurate predictions difficult to make.

Question 29

If scientists agree on the causes of climate change why does the media often present different opinions?

Answer 29

The media often present different opinions on climate change. These are often based on incomplete evidence or models that may be unreliable.

Question 30

Give 5 potential effects of global climate change.

Answer 30

Potential effects of global climate change include:

1. Extinction of species
2. Rising sea levels due to the polar ice caps melting leading to flooding.
3. Migration of people from flood or drought stricken areas.
4. Decrease in crop yields leading to famine.
5. Extreme weather events.

Question 31

What is the carbon footprint of a product, service or event?

Answer 31

The carbon footprint of a product, service or event is the total amount of CO2 and other greenhouse gases emitted over the full life cycle of that product, service or event.

Question 32

Give 3 ways a carbon footprint can be reduced.

Answer 32

A carbon footprint can be reduced by reducing emissions of carbon dioxide or methane by using renewable energy instead of fossil fuels, reducing the amount of transport or by off-setting by planting trees.

Question 33

How do trees reduce carbon dioxide concentrations in the atmosphere?

Answer 33

When trees photosynthesise they take carbon dioxide from the air and fix it into compounds in the tree. This traps the carbon dioxide and reduces the concentration in the atmosphere.

Question 34

Why is there a limit to how many trees can be planted?

Answer 34

There is a limit to how many trees can be planted as land is needed to grow crops.

Question 35

What activity is a major source of atmospheric pollutants?

Answer 35

Burning fuels is a major source of atmospheric pollutants.

Question 36

What 3 elements do most fuels contain?

Answer 36

Most fuels contain carbon and hydrogen and some contain sulfur. Burning these fuels will produce oxides of sulfur.

Question 37

How can sulfur emissions be reduced?

Answer 37

Sulfur can be removed from fuels before they are burned or sulfur dioxide can be removed from flue gas after burning.

Question 38

Write the equation for the complete combustion of propane. What greenhouse gas is produced?

Answer 38

Burning fuels in plenty of oxygen results in complete combustion and the production of carbon dioxide (a greenhouse gas) and water vapour.
eg) propane + oxygen → carbon dioxide + water vapour

Question 39

What is produced when fuels are burned with a restricted oxygen supply?

Answer 39

Burning fuels when oxygen is restricted can release water vapour, carbon dioxide, carbon monoxide.
eg) propane + oxygen → carbon dioxide + carbon + carbon dioxide + water vapour

Question 40

What is formed when fuels are burned in air at high temperatures?

Answer 40

When fuels are burned in air at high temperatures oxides of nitrogen are also formed as oxygen reacts with nitrogen in the air.

Question 41

How is acid rain produced?

Answer 41

Oxides of nitrogen and sulfur like NO2 and SO2 dissolve in water to make nitric acid and sulfuric acid. This causes rain to be acidic.
nitrogen dioxide + water → nitric acid
sulfur dioxide + water → sulfuric acid

Question 42

Why is carbon dioxide dangerous? When is it formed?

Answer 42

Carbon monoxide is produced during incomplete combustion . It is colourless and odourless but is toxic.
eg) propane + oxygen → carbon dioxide + carbon + carbon monoxide + water vapour

Question 43

What are particulates?

Answer 43

Incomplete combustion also results in the release of carbon particles into the atmosphere. We refer to these as particulates.

Question 44

What are 2 effects of particulates in the atmosphere?

Answer 44

Particulates cause global dimming and contribute to respiratory problems in humans.