C6.3 Flashcards
1
Q
Describe the Phase 1 of how our atmosphere evolved:
- the 1st billion years
A
- Phase 1 = volcanic activity released steam and CO2
- earths surface was molten and no atmosphere
- eventually surface cooled and a thin crust formed, but kept erupting, releasing gases from inside Earth = this is degassing = releases mainly CO2 but also steam, methane and ammonia
- when cooled down = early atmosphere was mostly CO2 and water vapour (which condensed to form oceans) and very little O2
2
Q
Describe the Phase 2 of how our atmosphere evolved:
- the 2nd and 3rd billions years
A
- Phase 2 = green plants evolved and produced O2
- lots of early CO2 was dissolved into oceans and Nitrogen gas (N2) was then put into the atmosphere in 2 ways = formed by ammonia when reacting with oxygen and by denitrifying bacteria
- N2 isn’t very reactive = amount of N2 in the atmosphere increased as it was made but not broken down
- green plays evolved and photosynthesised = remove CO2 and produce O2 and due to the plants the amount of O2 in air gradually built up and much of CO2 got locked in fossil fuels and sedimentary rocks
3
Q
Describe the Phase 3 of how our atmosphere evolved:
- last billion years or so
A
- Phase 3 = Ozone layer allows evolution of complex animals
- build up of oxygen in atmosphere killed off early organisms
- but allowed evolution of more complex organisms that made use of O2
- oxygen created the ozone layer (O3) which blocked harmful rays from the Sun and enabled even more complex organisms to evolve
- virtually any CO2 left
4
Q
How did nitrogen build up in our atmosphere?
A
- it built up as ammonia reacted with oxygen in the atmosphere and denitrifying bacteria
- it built up in the atmosphere as it isn’t very reactive so it didn’t break down
5
Q
What are the components that make up today’s atmosphere?
A
- 78% nitrogen
- 21% oxygen
- 0.9% argon
- 0.04% carbon dioxide
- water vapour and trace amounts or other gases
6
Q
What are pollutants?
A
- substances released into the environment that ,any harm living things
7
Q
What is carbon monoxide, CO?
A
- made during the incomplete combustion of fuels that contain carbon (happens when fuels are burnt in poor supply of oxygen or in vehicle engines)
- hydrogen + oxygen (in limited supply) —> carbon monoxide + carbon + water
8
Q
Why is CO dangerous?
A
- it’s a colourless, odourless and tasteless gas
- breathe it in = binds to haemoglobin in RBC = can’t take oxygen and lowers ability of RBC to carry oxygen = high amounts =suffocate
- symptoms = drowsiness, difficulty breathing, nausea, headache, death
9
Q
What are particulates?
A
- small particles produced during the incomplete combustion/ industrial processes (mainly pieces of carbon= particulate carbon)
- escape into atmosphere and float around and eventually deposit themselves as soot so lower quality of air (mainly particulate CO2)
- settle deep in lungs when breathed in and lead to bronchitis, breathing problems and increase chances of heat diseases
10
Q
What are acidic oxides?
A
- nitrogen and oxygen don’t normally react together as N has a triple bond between its atoms holding it together = lot of energy and high temp to break
- under high temp in vehicle engines = N reacts with O2 = NO (nitrogen monoxide) which oxidises to make NO2 (nitrogen dioxide)
11
Q
How are oxides of nitrogen written as?
A
- NOx
12
Q
How do nitrogen oxides cause acid rain?
A
- fossil fuels burnt = release CO2, sulfur dioxide and various nitrogen oxides and nitrogen oxide from reaction b/w oxygen in air and nitrogen
- as NO2 is released into the atmosphere = dissolves in water vapour of the cloud and forms acidic solution = dilute nitric acid which falls as acid rain
- power stations and internal combustion engines in car = main cause of acid rain
13
Q
What is photochemical smog?
A
- type of air pollution caused by sunlight acting on oxides of nitrogen which combine with oxygen in the air to produce the ozone (O3)
- ozone = breathing difficulties, headaches and tiredness
- ground level ozone is not the useful ozone layer in the atmosphere
14
Q
How does sulfur dioxide cause acid rain?
A
- fossil fuels burnt = release CO2 various nitrogen oxides and sulfur dioxide and sulfur dioxide (SO2) comes from sulfur impurities in fossil fuels (if breathed in = breathing difficulties)
- when they mix with clouds = form dilute sulfuric acid= falls as acid rain
- power stations and internal combustion engines in car = main cause of acid rain
15
Q
What problems do acid rain cause?
A
- erodes stonework (damages limestone building)
- corrodes metal
- kills trees
- kills living things in lakes and rivers (change of pH) as they become acidic and many plants and animals die as a result
16
Q
What does human activity affect carbon dioxide emissions?
A
- higher population = more respirating = more co2 given out
- more energy needed for lighting, cooking, transport and so on
- more countries = industrialised and well off = avg. energy demand per person is increasing = more energy consumption from fossil fuels
- more land to build houses on and grow food = make space by chopping trees (deforestation) = plants take out less co2 from air = co2 has risen over last 300 years significantly
17
Q
What is the greenhouse effect?
A
- Sun gives out electromagnetic radiation and some at most wavelengths pass through atmosphere and short wavelengths are absorbed by the Earth, warming our planet
- earth radiates heat radiation is absorbs as longer wavelength
(IR) and some IR is absorbed by greenhouse gases and seem is reflected back to the Earth by greenhouse gases - some IR radiation is re-emitted back into space
- absorption and reflection of IR radiation by greenhouse gases = keeps Earth warm and is very important
