The Earth is surrounded by atmosphere, which is a relatively thin collection of gases that surrounds the Earth. These gases are essential to life on earth. These are the layers off the atmosphere, in order from closest to the Earth’s surface to furthest from the Earth’s surface.
The area of the atmosphere closest to the Earth is called the troposphere, which is where most of the weather activity happens. The troposphere is the most dense part of the atmosphere.
Above the troposphere is the stratosphere, which is contains the ozone layer and also where aircrafts travel. The ozone layer plays a key role in maintaining and protecting life on Earth because it absorbs harmful uv radiation from the sun.
The layer above the stratosphere is the mesosphere. In this area of the atmosphere, meteors usually burn out. However, meteors that pass through the mesosphere and eventually through the troposphere are called meteorites (if it is actually able to hit the Earth’s surface).
Above the mesosphere is the thermosphere. Which is the area where many of our satellites are.
The layer above the thermosphere is the exosphere and is the outermost layer. The exosphere is the least dense part of the atmosphere.
|How high||Part of the Atmosphere|
The air is most dense in the troposphere as the air here is made of a mixture of gases. As you go further up the atmosphere, away from earth, the air gets less dense.
In the atmosphere the three main gases are nitrogen, oxygen and argon. Below is a table showing the percentage of the gases present in the atmosphere.
|Other gases (e.g. argon)||<1%|
Nitrogen and oxygen, which exist as molecules (groups in sets of 2 atoms), make up 99% of the atmosphere. The other gases are found in smaller amounts.
This is how the percentage of oxygen has changed overtime:
We can calculate the percentage of oxygen in the air by reacting it with copper.
The oxygen in the air reacts with the copper to form copper oxide, in the reaction:
Oxygen + Copper ⮕ Copper oxide
or more specifically
O2 + 2Cu ⮕ 2CuO
At the end, there should be no oxygen left in the air that was passed over the hot copper.
If you were to do a test, this is what you would typically find:
|Starting volume of the air in cm3||100|
|Ending volume of the air in cm3||79|
|Oxygen Volume in cm3 (Volume of air at the start – Volume of air at the end)||21|
To calculate the percentage of oxygen, the equation is:
Volume of oxygen ÷ Volume of air × 100
= 21 ÷ 100 × 100