The Earths Sea And Atmosphere

Question 1

Describe the earths atmosphere now

Answer 1

78% nitrogen
21% oxygen
1% argon
0.04% carbon dioxide

Question 2

Describe phase one of the evolution of the early atmosphere

Answer 2

The earths atmosphere was originally molten so any atmosphere just boiled away into space
Eventually a thin crust formed but volcanoes kept on erupting
The volcanoes gave out lots of gases like carbon dioxide and water vapour
This means the atmosphere was like that of mars and Venus now

Question 3

How were oceans formed

Answer 3

When the water vapour in the early atmosphere cooled and condensed

Question 4

Describe phase 2 of the evolution of the atmosphere

Answer 4

Lots of the co2 had also dissolved into the oceans
Green plants had evolved over most of the earth and were happy in the co2 atmosphere
They also removed co2 from the air and put oxygen into it this caused the oxygen levels in the atmosphere to slowly increase

Question 5

Describe phase 3 of the evolution of the early atmosphere

Answer 5

The build up of oxygen in the atmosphere killed off some of the earlier organisms but allowed more complex ones to develop
The oxygen also created the ozone layer which blocked some of the rays from the sun so even more complex organisms could form
Now there is very little co2 in the atmosphere

Question 6

Describe how our atmosphere is still changing from human activity

Answer 6

Human activity
burning fossil fuels releases co2
Deforestation means less co2 is taken from the atmosphere
Livestock farming releases huge amounts of Methane into the atmosphere

Question 7

Describe how the atmosphere is still changing because of volcanic activity

Answer 7

Sulfur dioxide can be thrown up high into the atmosphere where it can react with water sunlight or oxygen to from smog
Carbon dioxide is thrown up into the atmosphere by eruptions

Question 8

Why are sources of information on the early atmosphere limited

Answer 8

In the Antarctic each year a new layer of ice forms trapping air bubbles inside so if you go down really deep you can find bubbles from the early atmosphere and then see what gases are in the bubbles and also the early atmosphere
But because no one was actually there at the time scientists can never be certain most of the scientists just have guesses

Question 9

How can you do an experiment to show the proportion of gases in the atmosphere

Answer 9

When heated cooper reacts with oxygen in the air to form copper oxide so the reaction uses up oxygen
If you heat copper in a tube and pass air over it using two syringes you can see how much oxygen gets used up by the amount of oxygen still in the syringes
The chemical equation is 2Cu + O2 -> 2CuO

Question 10

Describe how co2 became locked up in sedimentary rock

Answer 10

When the organisms in the sea took in CO2 and then they die they are buried under layers of sediment and the co2 is trapped in the rocks