air and water Flashcards
how was earth’s early atmosphere formed?
intense volcanic activity produced lots of gases which formed the earth’s early atmosphere
what was the earth’s early atmosphere thought to contain? (4)
- mostly CO2
- little to no O2
- water vapour
- traces of other gases like N2, CH4 and NH3
how were oceans formed?
as the earth cooled, the water vapour in the earth’s early atmosphere condensed, forming oceans
why did the amount of CO2 in the earth’s atmosphere decrease? (2)
1) absorbtion by the oceans
2) absorption by plants and algae (through photosynnthesis)
how did the growth of primitive plants and algea affect the earth’s atmosphere? (2)
- increase in O2 (product of photosynthesis)
- decrease in CO2 (reactant of photosynthesis)
what is the chemical test for oxygen?
- to test for ocygen, put a glowing splint inside a test tube of the gas
- if oxygen is present it will relight the glowing splint
what is the earth’s current atmosphere made up of?
78% nitrogen
21% oxygen
~ 1% argon
>1% methane, water vapour and other gases
what is the greenhouse effect?
- sun emits short wavelength radiation which passes through the atmosphere
- the radiation reaches the earth’s surface and is re-emmited as long-wave length radiation
- this is absorbed by green house gases and release this thermal energy in the atmoshere, heating it up
- this creates the greenhouse effect
what are greenhouse gases?
gases such as water vapour, carbon dioxide and methane which act like an insulating blanket and keep the earth warm (cause the green house effect)
what types of human activity have affected the greenhouse effect and global warming? (3)
- increasing consumption of fossil fuels (releases CO2)
- deforestation (less CO2 removed from atmosphere)
- farming (methane from cows and rice paddies)
- all cause a rise of greenhouse gases in atmosphere leading to more global warming
why is it difficult to determine if humans are fully to blame for the rise in global temp (global warming)?
- historical date is quite inaccurate due to less data taken in less locations with less accurate methods
- therefore some scientists think that the rises in global temp are natural fluctuations
what are the effects of global warming and climate change?
(5)
1) polar ice caps could melt
2)changes in rainfall/water cycle
3) frequecy and severity of storms may increase
4) some areas will be too hot for people and animals
5) changes in food producing capacity
how does rising temps affect the absorption of CO2?
gases become less soluable as temps increase, so the oceans will be able to absorb less CO2 due to global warm and sea temps rising
what are the 3 main processes to make water potable?
- sedimentation
- filtration
- sterilisation/ chlorination
what are the main sources of potable water? (3/4)
- surface water
- ground water
- waste water
(4. sea water)
how can sea water be made potable?
distillation
what is potable water?
water that is safe to drink - different from pure water and contains dissolved substances
what must water in analysis not have?
aything dissolved in it - deionised water (water with ions present in tap water like Ca2+ removed)
what happens in filtration of water?
wire mesh, gravel and sand beds filter out large insoluable solids eg twigs
what happens in sedimention of water?
iron/aluminium sulfate is added to the water to make fine particles clump and settle at the bottom
what happens in chlorination of water?
chlorine gas is bubbled through to kill harmful bacteria and other microbes
