T9: chemistry of the atmosphere

Question 1

Why is there not a long of evidence for the early atmosphere?

Answer 1

Evidence for the early atmosphere is limited because of the long time scale of 4.6 billion years.

Question 2

What are the different ‘phases’ in the theories for how the earth’s atmosphere has evolved?

Answer 2

1) volcanoes gave out gases
2) oceans, algae and green plants absorbed carbon dioxide
3) algae and green plants produced oxygen

Question 3

What were the first billion years of earth’s history like?

Answer 3

Pretty explosive: the surface was covered in volcanoes that erupted and released a lot of gases (this is how we think the early atmosphere was formed).

Question 4

What was the early atmosphere like?

Answer 4

The early atmosphere was probably mostly carbon dioxide and virtually no oxygen. This is quite like the atmospheres of Mars and Venus today.

Question 5

How did volcanic activity change the atmosphere?

Answer 5

Volcanic activity released nitrogen which built up in the atmosphere over time as well as water vapour and small amounts of methane and ammonia.

Question 6

What happened to the water vapour in the atmosphere?

Answer 6

condensed to form oceans.

Question 7

What was the 3 things that cause the concentration of carbon dioxide in the atmosphere to decrease?

Answer 7

-oceans
-green plants and algae
-rocks

Question 8

How did the concentration of carbon dioxide decrease due to oceans?

Answer 8

Lot son carbon dioxide was removed from the early atmosphere as it dissolved in the oceans. This dissolved carbon dioxide then went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.

Question 9

How did the concentration of carbon dioxide decrease due to green plants and algae?

Answer 9

Green plants and algae evolved and absorbed some of the carbon dioxide so that they could carry out photosynthesis.

Question 10

What happened to marine animals (during phase 2)?

Answer 10

Later marine animals evolved as they formed shells and skeletons containing carbonates from the atmosphere.

Question 11

What happens when plants, plankton and marine animals die?

Answer 11

• they fall to the seabed and get buried by layers of sediment.
• Over millions of years they become compressed and form sedimentary rocks, oil and gas; trapping the carbon within them and helping to keep carbon dioxide levels in the atmosphere reduced.

Question 12

How did the concentration of carbon dioxide decrease due to rocks?

Answer 12

Some of the carbon these organisms (the evolved marine animals) took in from the atmosphere and oceans became locked up in rocks and fossil fuels after these organisms died.

Question 13

What are the fossil fuels?

Answer 13

Things like coal, crude oil and natural gas that are made by this process are called fossil fuels.

Question 14

How is crude oil and natural gas formed?

Answer 14

Formed from the deposits of plankton. These fossil fuels form reservoirs under the seabed where they get trapped in rocks.

Question 15

What is coal and how is coal formed?

Answer 15

Coal is a sedimentary rock made from thick plant deposits.

Question 16

What is limestone and how is it formed?

Answer 16

Limestone is also a sedimentary rock. It’s mostly made of calcium carbonate deposits from the shells and skeletons of marine organisms.

Question 17

How did the concentration of oxygen change and why?

Answer 17

Increased as green plants and algae produced oxygen by photosynthesis: where plants use light to convert carbon dioxide and water into sugars.

Question 18

When was oxygen first produced?

Answer 18

Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved.

Question 19

What happened as oxygen levels changed?

Answer 19

As the oxygen levels/percentage built up in the atmosphere over time, more complex life (animal life) could evolve.

Question 20

For the past 200 millions years, what has the atmosphere been like?

Answer 20

the proportions of different gases in the atmosphere have been much the same as they are today:
- about four-fifths (approximately 80%) nitrogen
- about one-fifth (approximately 20%) oxygen
- small proportions of various other gases(each only makes up less than 1% of the atmosphere) , including carbon dioxide, water vapour and noble gases.

Question 21

What are the greenhouse gases and what do they do?

Answer 21

Carbon dioxide, methane and water vapour act as an insulating layer in the earth’s atmosphere- this, among other factors, allows the earth to be warm enough to support life.

Question 22

What do all particles do?

Answer 22

All particles absorb certain frequencies of radiation/

Question 23

Describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.

Answer 23

-Greenhouse gases don’t absorb the incoming short wavelength radiation from the sun but they do absorb the long wavelength radiation that gets reflected back off the earth.
- Then they re-radiate it in all directions; including back towards the earth.
- The long wavelength radiation is thermal radiation, so it results in warming of the surface of Earth.

Question 24

What forms of human activity affect the amount of greenhouse gases in the atmosphere?

Answer 24

deforestation, during fossil fuels, agriculture and creating waste.

Question 25

How does deforestation affect the amount of greenhouse gases in the atmosphere?

Answer 25

Fewer trees means less carbon dioxide is removed from the atmosphere via photosynthesis.

Question 26

How does burning fossil fuels affect the amount of greenhouse gases in the atmosphere?

Answer 26

Carbon that was 'locked up' in these fuels is released as carbon dioxide.

Question 27

How does agriculture affect the amount of greenhouse gases in the atmosphere?

Answer 27

More farm animals produce more methane through their digestive process.

Question 28

How does creating waste affect the amount of greenhouse gases in the atmosphere?

Answer 28

More landfill sites and more waste from agriculture means more carbon dioxide and methane released by the decomposition of waste.

Question 29

What has increasing carbon dioxide been linked to and why?

Answer 29

The earth's temperature varies but recently the average temperature of the Earth's surface has been increasing. Scientists agree, through peer pressure (so information is reliable) that extra carbon dioxide produced from human activity is causing this increase and that it will lead to CLIMATE CHANGE.

Question 30

Why is it difficult to fully understand the earth's climate?

Answer 30

because it is so complex (complex system) and there are so many variables that it is very hard to make a model that is not oversimplified.

Question 31

What has not being able to fully understand the earth's climate lead to?

Answer 31

speculation, particularly in the media- where stories may be biased or only some/part of the information is given.

Question 32

What are the 4 dangerous consequences of climate change?

Answer 32

1) Higher global temperatures are causing the polar ice caps to melt, causing SEA LEVELS TO RISE. If sea levels keep rising, this will lead to increased flooding in costal areas and costal erosion. 2) Changes in rainfall patterns (amount, timing and distribution) are causing too much or too little water. This along with temperature changes may affected the ability of certain regions to produce food. 3) The frequency + severity of storms may also increase. 4) Changes in temperature + the amount of water available in different habitats are affecting wild species, leading to changes in their distribution.

Question 33

What is carbon footprint?

Answer 33

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 34

Why is measuring the total carbon footprint of something very difficult?

Answer 34

As the are so many different factors to count, e.g the emission released sourcing the parts, making it, using it and disposing it.

Question 35

Why is a rough calculation of total carbon foot print still useful?

Answer 35

Can give a good idea of what the worst emitters are so that people can avoid them in the future.

Question 36

How can the carbon footprint be reduced?

Answer 36

The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane (greenhouse gases)

Question 37

What are the 5 methods to reduce carbon footprint?

Answer 37

* renewable energy resources/ nuclear energy used instead of fossil fuels. * use more efficient processes to conserve energy and cut waste. * Governments could tax companies based on the amount of green house gases they emit. * Governments can put a cap on emissions of all greenhouse gases that companies make- sell licence for emissions up to that cap. * Technology captures CO2 produced by burning fossil fuels before it's released into the atmosphere.

Question 38

How would more efficient process reduce carbon footprint?

Answer 38

Lots of waste decomposes to produce methane, so this will reduce methane emissions.

Question 39

How could Governments taxing companies based on the amount of green house gases they emit reduce carbon footprint?

Answer 39

taxing cars based on the amount of CO2 they emit over a set distance could mean that people choose to buy ones that are more fuel efficient and so less polluting.

Question 40

How can the carbon dioxide captured by technology be stored?

Answer 40

stored deep underground in cracks in the rock such as old oil wells.

Question 41

Why is making actions for carbon footprint reductions limited? (4)

Answer 41

- a lot of works to be done on alternative technologies that result in lower CO2 emissions. - lots of governments worried the changes will impact economic growth of communities which could be bad for people's well being (particularly for developing countries) - Not all on board so hard to make international agreements to reduce emissions. - Individuals in developed countries don't want to make changes to their lifestyle and there isn't enough educations provided about why the changes are necessary and how to make them.

Question 42

Why does all not being on board with reducing carbon footprint make action limited?

Answer 42

Most countries don't want to sacrifice their economic development if they think that others won't do the same?

Question 43

What do fossil fuels contain?

Answer 43

fossil fuels, such as crude oil and coal, contain hydrocarbons

Question 44

What happens during combustion of fossil fuels?

Answer 44

The carbon and hydrogen in the hydrocarbons are oxidised so that carbon dioxide and water vapour are released into the atmosphere.

Question 45

When does complete combustion occur?

Answer 45

When there is plenty of oxygen and all of the fuel burns.

Question 46

When does incomplete combustion occur and what does it produce?

Answer 46

- if there is not enough oxygen, some of the fuel doesn't burn - solid particles (called particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide is produced as well as CO2.

Question 47

What are the problems caused by particulates in the air?

Answer 47

- If particulates are inhaled, they can get stuck in the lungs and cause damage, leading to RESPIRATORY PROBLEMS. - They're bad for the environment as they or the clouds they help to produce reflect sunlight back into space. This means that less light reaches the Earth causing GLOBAL DIMMING.

Question 48

What are the problems caused by carbon monoxide?

Answer 48

- stops your blood from doing its proper job of carrying oxygen around the body. - binds to the haemoglobin in your blood that normally carries O2 so less oxygen is able to be transported round your body. - lack of oxygen in the blood can lead to fainting, a coma and even death. - Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.

Question 49

How is sulfur dioxide released?

Answer 49

during the combustion of fossil fuels such as coal that contain sulfur impurities- the sulfur in the fuel become oxidised.

Question 50

How can you test for sulfur impurities in a fuel?

Answer 50

by bubbling the gases from combustion through a solution containing universal indicator- if the fuel contain sulfur the gases will contain SO2 which will will dissolve to form an acidic solution and turn the universal indicator red.

Question 51

How is nitrogen oxides created?

Answer 51

from a reaction between the nitrogen and oxygen in the air, caused by the heat of the burning. (This can happen in the internal combustion engines of cars).

Question 52

What are the problems of sulfur dioxide and nitrogen oxides?

Answer 52

Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.

Question 53

How do sulfur dioxides and nitrogen oxides cause acid rain?

Answer 53

When these gases mix with clouds they form dilute sulfuric acid or dilute nitric acid which then falls as acid.

Question 54

What are the problems of acid rain?

Answer 54

-kills plants - damages buildings and states - corrodes metal