C9 Earth's atmosphere

Question 1

Early atmosphere

Answer 1

mostly nitrogen and carbon dioxide released by volcanoes because similarity to venus and mars

Question 2

Change to the atmosphere

NH3, CH4, CO2, N2, O2

Answer 2

Oxygen came from photosynthesis in living creatures

Ammonia in air reacted with oxygen to form nitrogen

Methane reacted with oxygen to form water and carbon dioxide

Carbon dioxide was dissolved in the oceans or used in photosynthesis

Nitrogen gradually built up in the atmosphere, evolution of denitrifying bacteria reacting nitrate into nitrogen

Oceans formed as water vapor condensed and fell

Question 3

Composition of the current atmosphere in dry air

Answer 3

78% nitrogen
21% oxygen
0.9% carbon dioxide
0.04 argon

‘dry air’ removes factor of humidity (water vapor)

Question 4

Pathways of CO2

Answer 4

Co2 dissolved in oceans
insoluble compounds become sediment forming sedimentary rock

soluble compounds taken up by animals, when they die their skeletons become sediment forming sedimentary rock

Co2 used photosynthesis
plankton in oceans decay under heat and pressure to form crude oil and natural gas

swamp plants decay under heat and pressure to form coal

Question 5

greenhouse gases

Answer 5

allows Sun’s smaller λ UV radiation to pass, but absorbs some of the Earth’s longer λ IR radiation

Question 6

increase of carbon dioxide

Answer 6

industrilisation = more fossil fuels burned

deforestation = less photosynthesis

Question 7

increase of methane

Answer 7

increase of dairy industry = more cattle releasing more methane

increase of rice farming = more paddies release more methane

increasing size of landfills = rotting waste releases more methane

Question 8

peer review

Answer 8

valid, original, significant

Question 9

global warming impacts

Answer 9

• rising sea levels, melting ice caps
• severe climate
• increase water stress
• reduce biodiversity as ecosystem disrupted
• limited food production due to climate

Question 10

carbon footprint

Answer 10

the total amount of greenhouse gases emitted as a result of the total lifespan of a product, service or event

Question 11

ways to reduce carbon footprint

Answer 11

• carbon capture and storage
  prevent release to atmosphere and store underground

-carbon tax
encourage companies and people to use more efficient products

-carbon off-setting
create a netzero effect by neutralising for co2 emissions e.g. planting trees to absorb carbon dioxide

-carbon neutral fuels
zero net release of greenhouse gases e.g. burning ethanol from plants = co2 released = co2 absorbed by plants

-renewable energy sources
lower carbon footprint than fossil fuels

-energy conservation
efficiency

Question 12

barriers to reducing greenhouse gases

Answer 12

-economic factors
developing countries still use fossil fuels for cost-efficiency, implementing methods are expensive

-impact on lifestyle
electricity consumption must be lowered, but population increasing

-not educated

-scientific disagreement

-international disagreement

Question 13

carbon dioxide as a pollutant

Answer 13

formed from complete combustion

contributes to the greenhouse effect

stop burning fossil fuels

Question 14

carbon monoxide

Answer 14

formed from incomplete combustion
toxic
combust in good supply of oxygen

Question 15

soot (carbon)

Answer 15

formed from incomplete combustion
blackens buildings
combust in good supply of oxygen

Question 16

sulfur dioxide

Answer 16

formed from presence of sulfur in fossil fuels being burnt
acid rain
flue gas desulfurisation with caco3 filter

Question 17

nitrogen oxides NOx

Answer 17

nitrogen and oxygen react in high temperatures in the air i.e. engine
acid rain
catalytic converter removes this

Question 18

unburned hydrocarbons

Answer 18

failed combustion
waste of money
engine efficiency