The matter is anything that occupies space. Air is a matter which is inevitable in our lives. The earth is covered with a blanket of air called the atmosphere. Among the few fundamental elements, it is the most important because no life can exist for a pulse of time without it. It is needed by every single organism for their survival. In addition to breathing, it has an influential role on abiotic components of environment like wind, rain, climate, etc. Let’s learn about its composition and properties in detail.
Chemical Composition of Air
Air is a mixture of gases which makes up the Earth’s atmosphere. These gases are colorless, odorless and hence we can’t see them but only feel.
|Composition of Dry Air|
|Element||Volume by %||Weight by %||PPM(Parts per Million) by Volume||Symbol of the Element||Molecular Weight of the element|
|Xenon||8.7 x 10-6||0.00004||0.087||Xe||131.30|
The atmosphere is an ocean of these gases. It consists of 78% nitrogen, 21% oxygen and 1 % other gases and water vapour. The moisture content varies from place to place. Arid regions have less moisture content as compared to wetlands.
- The water vapor or moisture content of air varies. The maximum moisture carrying capacity of air depends primarily on temperature
- The composition of air is unchanged until elevation of approximately 10.000 m
- The average air temperature diminishes at the rate of 0.6oC for each 100 m vertical height
- “One Standard Atmosphere” is defined as the pressure which is equal to that exerted by a 760 mm column of mercury at 0°C sea level and at standard gravity (32.174 ft/sec2)
Other components in air
- Sulfur dioxide(SO2 ) – 1.0 ppm
- Methane(CH4 )2.0 ppm
- Nitrous oxide(N2O) – 0.5 ppm
- Ozone(O3 ) 0 to 0.07 ppm
- Nitrogen dioxide(NO2 ) – 0.02 ppm
- Iodine(I2) 0.01 ppm
- Carbon monoxide(CO) – 0 to trace ppm
- Ammonia(NH3 ) 0 to trace ppm
As mentioned earlier, gases are matter.They exhibit certain properties like any other matter. Some common properties are as follows:
Colorless and odourless:
Air generally has no color or odour. It is an invisible matter that can only be felt. All living things breathe air for their survival. Moving air is called the wind.
It is a mixture of different gases. Hence, like every other matter, they also occupy space. On blowing, a balloon expands because the air being blown into it fills in the empty space.
Air exerts pressure:
It has weight, and the pressure exerted by the weight of air is known as air pressure. Due to gravity, this mixture of gases near the surface is denser than at high altitudes. This is why the gaseous atmosphere in mountains is thinner than that at the surface.
Another property is its expanding property. On heating, it expands and occupies more space. More it expands, more it becomes thinner. Hence, the pressure of warm wind is lower than that of cold wind.
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