C13: Earth’s Atmosphere

Question 1

Composition of atmosphere ?

Answer 1

80% NITROGEN
20% OXYGEN
CO2
Water vapour
Noble gases

Question 2

Why are we not certain about earth’s early atmosphere ?

Answer 2

Earth is 4.6 billion yrs old , so lack of evidence

Question 3

How did 02 appear ?

Answer 3

PHOTOSYNTHESIS
- 6CO2 + 6H2O —> 6O2 + C6H12O6
- green plants release oxygen

• ALGAE increased 02 in atmosphere

Question 4

How did CO2 reduce ?

Answer 4

FORMATION OF SEDIMENTARY ROCK
- as ocean formed , CO2 dissolved to form soluble carbonate compounds so amount of C02 decreased
- carbonate compounds were PRECIPITATED as sedimentary rock

UPTAKE FROM LIVING ORGANISMS
- CO2 taken from algae and plants when they photosynthesise
- these organisms turn to fossil fuels —> COAL

Question 5

How did water vapour reduce ?

Answer 5

Water vapour condensed to form oceans after volcanic eruptions

Question 6

What is the greenhouse effect?

Answer 6

The way in which heat is trapped close to earth’s surface by ‘greenhouse gases’

Question 7

Importance of greenhouse gases?

Answer 7

• essential to keep planet at good temp for life
• otherwise heat would escape and it would average -20C

Question 8

How does greenhouse effect work?

Answer 8

EM radiation from sun passes through Earth’s atmosphere
- Earth absorbs some radiation/ warms up . But some heat is radiated from Earth as infrared radiation
- some of the IR radiation is absorbed by greenhouse gases in atmosphere
- atmosphere warms up leading to greenhouse effect

Question 9

Consequence of raise in greenhouse gases ?

Answer 9

• flooding
• desertification
• melting glaciers
• pollution

Question 10

Carbon footprint ?

Answer 10

Total amount of greenhouse gases that are generated by our actions

Question 11

How to reduce carbon footprint ?

Answer 11

• reduce CO2 and methane emissions by:
• using less electricity/ transport
• more trees
• carbon capture

Question 12

How is SO2 formed, problems and solutions ?

Answer 12

FORMED : sulfur impurities in fuels burn to form SO2
PROBLEMS : acid rain
SOLUTIONS : - use renewable energy
- remove from fuels before burning
- remove from flue gases

Question 13

N20 how is it formed, problems and solutions?

Answer 13

Formed : oxidation of N2 in high temps in vehicle engines
PROBLEMS : acid rain /asthma
SOLUTIONS :low nitrogen fuels

Question 14

How are unburned fuels formed , problems and solutions ?

Answer 14

FORMED: release in INCOMPLETE combustion of fuel
PROBLEMS : damage cells/ cancer
SOLUTIONS : check up of engines

Question 15

How is H20 formed , problems?

Answer 15

FORMED : oxidation of H2 I hydrocarbon fuels
PROBLEMS : amplify water cycle ( more wet/dry regions)

Question 16

How is CO2 formed , problems and solutions ?

Answer 16

FORMED: complete combustion of fuel
Problems : increases temperature
SOLUTIONS : reduce use / alternate energy source

Question 17

How is CO formed , problems and solutions ?

Answer 17

FORMED : incomplete combustion of fuel
PROBLEMS : toxic poisonous gas / odourless so hard to detect
SOLUTIONS : use detectors and biodiesel

Question 18

How is soot/particulates formed, problems and solutions ?

Answer 18

FORMED : incomplete combustions of fuel leads to solid particles / unburned hydrocarbons to be released forming PARTICULATES
PROBLEMS: global dimming/health problems
SOLUTIONS : reduce use of them

Question 19

composition of early atmosphere

Answer 19

mainly Co2
no oxygen
traces of ammonia

Question 20

why is producing future models for climate chnage difficult?

Answer 20

• complex system
• many variables
• many alternative theories