The Atmosphere Flashcards
1
Q
What does todays atmosphere contain?
A
- 78% nitrogen
- 21% oxygen
2
Q
What does the early atmosphere contain?
A
- mostly carbon dioxide
- little oxygen
3
Q
How did the early atmosphere get so much co2 within it?
A
There were many volcanic eruptions which released large amounts of CO2 into the atmosphere
4
Q
Why did the atmosphere change?
A
- As water vapour condensed into the oceans it creates a weak acid- this reacted with minerals in the ocean to form precipites
- Over time this formed sediments of carbonate in the sea bed
- Carbon dioxide in the ocean was used to form coral and the shells of organisms- when they died they formed the sedimentary rock limestone- this removed CO2 from the atmosphere
- Oxygen came from photosynthetic algae performing photosynthesis= oxygen which entered the atmosphere
- Over the years the level of oxygen built up to a point were animals could survive
- Photosynthesis also takes in carbon dioxide so fossil fuels form and when plants die this then removes CO2 from the atmosphere
5
Q
Compare the early atmosphere to todays atmosphere?
A
Early= large amounts of CO2
Todays= contains small amounts
&
Early= little oxygen
Todays= 21% of the earths atmosphere
6
Q
How is coal formed?
A
- formed form the remains ferns and trees
- if they die in wet marshlands they can’t decompose
- this may be due to a lack of oxygen or acidic conditions- prevent bacteria from decomposing
- over time the plant remains are covered in sediment and compressed
- high temps and pressure creates coal
7
Q
How is oil formed?
A
crude oil is formed from tiny plankton which is formed from tiny plants and animals found in the sea:
- when they die they settle in the mud on the sea bed
- if oxygen isn’t present then they can’t decompose
- heat and pressure then covert them into crude oil
8
Q
What do all fossil fuels contain?
A
All contain carbon which is taken in during photosynthesis
