Development Of The Earths Atmosphere Flashcards
Description of the atmosphere 4.5 billion years ago:
- Atmosphere mostly water vapour
- water condensed
- earth cooled
Description of the earths atmosphere 4 billion years ago:
- mostly CO2
- photosynthesising algae
- oxygen produced
Description of the earths atmosphere 2.5 billion years ago:
- mostly nitrogen + CO2
- respiring animals evolved
- balance of CO2 and O2
Description of the earths atmosphere 200 million years ago:
- mostly nitrogen and O2
- atmosphere stabilised
- CO2 ⬆️ O2⬇️
What are the percentages of gases in the earths atmosphere today?
Oxygen- 21%
Nitrogen- 78%
Argon- 0.9%
CO2- 0.04%
Other gases- 0.06%
Name 4 gases present in the early atmosphere of the earth:
Carbon dioxide, methane, ammonia, steam
Where do some scientists thing that life first evolved?
Near underwater volcanoes
How did oxygen appear in the earths atmosphere?
Photosynthesising algae (blue-green) used up CO2 and water, and by photosynthesis made O2.
What layer did oxygen form in the upper atmosphere?
The ozone layer
Why is the ozone layer important for life on land?
It stopped harmful UV light getting into the atmosphere.
How does fractional distillation work?
Air is cooled at -200C and the solid CO2 and water is removed. The remaining liquid is fed into the bottom of the fractionating column which is warmer at the bottom than the top. The temperature at the bottom of the column is high than the boiling point of nitrogen so it boils, rises up the column and is piped off as a gas at the top. Oxygen and argon have higher boiling points so they remain as liquids and are piped off at the bottom of the column.
Air liquefies at what temperature?
-200C
Which gas is removed from the top of the fractionating column when the liquefied air is distilled?
Nitrogen
Give a definition of fractional distillation:
A method of separating mixtures of liquids according to their boiling points.
What else can be separated by factional distillation?
Crude oil
