The document discusses the composition of Earth's atmosphere and processes that remove carbon dioxide from the air. It states that the major gases in the atmosphere by percentage are nitrogen (78%), oxygen (21%), argon (0.9%), and carbon dioxide (0.04%). It explains that carbon is locked away through processes like limestone formation, absorption by oceans and plants, and being stored as fossil fuels. Fractional distillation is presented as a method to separate air gases by using differences in their boiling points.

1. Gases in the atmosphere
LOs:
• Propose the composition of
Earth’s atmosphere.
• Describe processes that lock away
carbon from the air.
• Explain how the gases in air can
be separated.

2. Gases in the atmosphere
Gas %
Oxygen
Carbon Dioxide
Nitrogen
Argon
0 9 . 7
2 0
8 4 1 .
0

3. Gases in the atmosphere
Gas %
Oxygen 21
Carbon Dioxide 0.04
Nitrogen 78
Argon 0.9
1
Oxygen
Carbon Dioxide 2
Nitrogen 3
Argon 4

4. Gases in the atmosphere
LOs:
• Propose the composition of
Earth’s atmosphere.
• Describe processes that lock away
carbon from the air.
• Explain how the gases in air can
be separated.

5. Sherlock Holmes and the
‘Case of the Disappearing Carbon Dioxide’
Great Scott
Holmes! Where Sedimentary,
has all the my dear
carbon dioxide Watson.
gone?

6. Carbon Sinks
Carbon has been locked up in the Earth –
Limestone / chalk (CaCO3)
Oceans
Rainforests
Fossil Fuels
Living things

7. FAMILY FORTUNES
We asked 100 people where’s the carbon dioxide gone
X 1 Limestone
X
38
2 Oceans 20
X 3
4
Rainforests
Fossil fuels
16
13 X
X 5 All living things 13
X

8. Gases in the atmosphere
LOs:
• Propose the composition of
Earth’s atmosphere.
• Describe processes that lock away
carbon from the air.
• Explain how the gases in air can
be separated.

9. Fractional Distillation
(Separating compounds by boiling point into fractions)
Separating the gases in air:
Make it very cold so liquefies
then allow to slowly warm COLDER
up and collect one gas.
Gas Boiling point
Nitrogen -196oC
Argon -186oC WARMER
Oxygen -183oC
Carbon Dioxide -78oC

10. What use are the gases?
Gas Use
Make ammonia
Nitrogen Inert – use in food packaging e.g. crisps
Use to cool things e.g. sperm samples
Argon Very inert – Use in light bulbs
Oxygen Hospitals – Help breathing
Welding
Carbon Dioxide Stage shows – dry ice
Use to cool things e.g. chemicals

11. Removing two villains
The Earth may have originally stunk
of babies nappies and cow farts….all
because of ammonia and methane
respectively.
What happened to these?

12. Try summary question
2 p.215
Use p. 214 to help.
Ex. p.218 Q3
Extension
p.218 Q3

13. Self-Assessment
2.a) fractional distillation
b) Removed from liquified air as solids at -200C
c)i) Argon
ii) Oxygen + Argon have similar b.p. so often
produce a mixture.

14. 5%
Self-Assessment
25% 25% 1
1
Nitrogen 2
2
40% Oxygen 3
3 75%
Methane 4
4
30% Ammonia
a) How did the atmosphere of the planet change?
Amount of ammonia, methane and oxygen decreased, nitrogen increased
b) What might have caused the change in part a?
Oxygen reacted with ammonia and methane
c) Copy and complete the word equations to explain the shift
oxygen water
i) Methane + ……………………….. Carbon dioxide + …………………………
oxygen water
ii) Ammonia + ……………………….. Nitrogen + ……………………………

15. Gases in the atmosphere
LOs:
• Propose the composition of
Earth’s atmosphere.
• Describe processes that lock away
carbon from the air.
• Explain how the gases in air can
be separated.