Earth's Atmosphere

Question 1

Composition of the Earth’s Atmosphere today?

Answer 1

1. nitrogen (78%)
2. oxygen (21%)
3. Argon (0.93%)
4. carbon dioxide (0.035%)
5. water vapor + traces of other gases (noble gases)
   Our current atmosphere has been roughly the same for nearly 200 million years

Question 2

Composition of the Earth’s Atmosphere billions of years ago?

Answer 2

1. Carbon dioxide (95%)
2. Water vapour (4%)
3. Traces of other gases - nitrogen, ammonia and methane
   The atmosphere about 3,500 million years ago would’ve been similar to mars atmosphere today

Question 3

What happened to the nitrogen and why?

Answer 3

The level of Nitrogen increased because it was

1. Released by volcanoes
2. Ammonia reacted with the oxygen to form nitrogen

Question 4

What happened to the oxygen and why?

Answer 4

The level of oxygen increased because it was

1. Produced due to photosynthesis of early organisms (cyanobacteria)
2. Later plants alro released oxygen

Question 5

What happened to the carbon dioxide and why?

Answer 5

The levels of carbon dioxide decreased because it was

1. Dissolved in the oceans
2. Photosynthesis of early organisms + plants absorbed the carbon dioxide
3. marine organisms used it to make shells
4. shells formed sedimentary rocks like limestone that locked up carbon dioxide

Question 6

What happened to the water vapour and why?

Answer 6

The levels of water vapour decreased because water vapour condensed into clouds when the earth cooled and then formed our oceans

Question 7

List the greenhouse gases

Answer 7

1. Water
2. Carbon dioxide
3. methane

Question 8

How does the greenhouse gas effect work?

Answer 8

Short wavelengths of radiation from the sun (UV or Visible Light) enter the earth’s atmosphere
Radiation is absorbed by the Earth’s surface and then re-emitted when the earth cools at a higher wavelength
Some radiation is transmitted into space and some is absorbed by greenhouse gases
This means the heat cannot escape and lead to global warming

Question 9

What is the difference between climate and weather?

Answer 9

weather is the change in atmospheric conditions and climate is the weather pattern

Question 10

what is combustion?

Answer 10

burning - usually in air/oxygen

Question 11

What kind of reaction is combustion?

Answer 11

exothermic

Question 12

What happens when you burn a fuel? Name an example

Answer 12

natural gas/ methane - fuel stores potential energy which is released as heat when burnt

Question 13

What is the difference between complete and incomplete combustion?

Answer 13

Complete combustion takes place in the presence of a sufficient amount of oxygen while an incomplete combustion reaction takes place when there is an insufficient amount of oxygen supply.

Question 14

What is complete combustion?

Answer 14

fuel + excess oxygen → carbon dioxide + water vapor

Question 15

Complete combustion gas flame colour?

Answer 15

blue

Question 16

What is incomplete combustion?

Answer 16

fuel + not enough oxygen → carbon monoxide + water

+ soot can be produced (&/or)

Question 17

Incomplete combustion gas flame colour?

Answer 17

yellow

Question 18

methane complete combustion?

Answer 18

CH4 + 2O2 → CO2 + 2H2O

Question 19

methane incomplete combustion?

Answer 19

2CH4 + 3O2 → 2CO + 4H2O

CH4 + O2 → C + 2H2O - less oxygen

Question 20

What are the products of combustion and their effects?

Answer 20

1. water vapour - harmless
2. CO2 - greenhouse gas = global warming
3. CO - toxic
4. unburnt carbon - particulate (pollutant)
5. SO/SO2 - acid rain
6. NO/NO2 - acid rain

Question 21

Complete combustion for propane?

Answer 21

C3H8 + 5O2 → 3CO2 + 4H2O

Question 22

Incomplete combustion for propane?

Answer 22

2C3H8 + 7O2 → 6CO + 8H2O

C3H8 + 2O2 → 3C + 4H2O

Question 23

Possible products of burning fossil fuels?

Answer 23

1. Sulphur dioxide
2. Water
3. Carbon dioxide
4. Carbon monoxide
5. Soot/particulates
6. Unburned fuels
7. Nitrogen oxides

Question 24

Sulphur dioxide

1. How is it formed?
2. Problems?
3. Solutions?

Answer 24

SO2

1. Combustion of fuels containing S (sulphur)
2. Causes acid rain
3. Remove S before burning; react fumes with CaO/CaO3 - flue gas desulphurisation

Question 25

Water

1. How is it formed?
2. Problems?
3. Solutions?

Answer 25

H20

1. Combustion of fuels containing H (hydrogen)
2. None - H2O is a greenhouse gas but not a problem as it is naturally maintained

Question 26

Carbon Dioxide

1. How is it formed?
2. Problems?
3. Solutions?

Answer 26

CO2

1. Complete combustion of fuels containing C (carbon)
2. Greenhouse gas - causes global warming
3. Burn less fossil fuels

Question 27

Carbon Monoxide

1. How is it formed?
2. Problems?
3. Solutions?

Answer 27

CO

1. Incomplete combustion of fuels containing C (carbon)
2. Toxic
3. Ensure good oxygen supply (air) when fuel is burning

Question 28

Soot / particulates

1. How is it formed?
2. Problems?
3. Solutions?

Answer 28

C

1. Incomplete combustion of fuels containing c (carbon)
2. Global dimming + blackens buildings
3. Ensure good oxygen supply (air) when fuel is burning

Question 29

Unburned Fuels

1. How is it formed?
2. Problems?
3. Solutions?

Answer 29

1. Some fuel may not burn
2. Wastes fuel and some fuels might be greenhouse gases (CH4)
3. Make sure engine is well tuned

Question 30

Nitrogen oxides

1. How is it formed?
2. Problems?
3. Solutions?

Answer 30

NO / NO2

1. Reaction between N2 and O2 in the air at high temps
2. Causes acid rain
3. Use a catalytic converter in cars

Question 31

What is carbon footprint?

Answer 31

The total amount of carbon dioxide and other greenhouse gases emitted over a full life cycle

Question 32

What are the 5 methods for reducing CO2 levels

Answer 32

1. Carbon capture and storage
2. Decrease demand for meat
3. Biofuels which are carbon neutral
4. Insulate homes
5. Replacing cut down trees - offsetting

Question 33

What does carbon neutral mean

Answer 33

Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint.