Transcript
© MDR PUBLISHING 2011
Gases around us
Are made of particles
These are invisible
Consist of…….
Nitrogen
Oxygen
Water Vapour
Carbon Dioxide
Argon
Helium and HydrogenIn the upper atmosphere
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The particles in a gas are…
separated by large spaces
free to move
THIS MEANS THAT GASES CAN……
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…be poured
…easily change shape
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Each tiny particle in a gas has a mass. If you add these up …………….…
A balloon contains 2g of air
1 m3 contains about 1 kg of air
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The mass of air pushing down on every m2 of the earth’s surface is huge…
About 10 tonnes / m2
Or 10 elephants standing on each other
SO WHY DOESN’T THE TABLE BREAK?
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Because air is a fluid,
Pressure acts in all directions at once
The pressure pushing DOWNIs balanced by
The pressure pushing UP
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The air in DRY atmosphere is made from 4 Gases
NITROGEN 78%
OXYGEN 21%
ARGON 0.9 %
Carbon Dioxide 0.03%
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NITROGEN 78%
Used help plants grow
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OXYGEN 21%
Burns fuels…
Carbohydrates Hydrocarbons
To Produce ENERGY
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OXYGEN 21%
Burns fuels…
Carbohydrates Hydrocarbons
To Produce ENERGY
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Carbon Dioxide
Has a larger density than air
Is TOXIC for animals
But is used by plants during photosynthesis
To make OXYGEN, SUGARS and STARCHES
Starches
CO2
O2Sugars
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It is used …..
In fire extinguishers
In Fizzy drinks
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ARGON
Is an INERT gas
Which means it doesn’t react
Used as anartificial
atmosphereIn light bulbs
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HELIUM
Is an also an INERT gas
It has a much lower density than air
and so a Helium balloon will float
upwardswhen released
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HYDYOGEN
Is a very useful clean fuel
When It burns in Oxygen
It releases a lot of energy
And produces only WATER
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The air around us also contains water vapour
The amount of water Vapour is called the HUMIDITY
This changes from place to place
Rain forest Arctic Desert
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HUMIDITY
Varies from season to season
It depends on how much water is evaporating into the air
This depends on the CLIMATE
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