The earth is surrounded by an invisible blanket of air. It is all around us and makes up the atmosphere.
Air is invisible and odorless, and critical to all life on earth. So, what exactly constitutes air? Is it a mixture, compound, or element?
Air is a homogeneous mixture of naturally occurring gases. It also contains trace elements of human pollutants, dust particles, and water vapor. So, let’s learn more about air.
Is air an element?
Air is not an element. An element cannot be broken down into simpler components through a chemical process.
Air contains several gaseous compounds like oxygen, hydrogen, and nitrogen and inert gases like Argon (Ar) and Helium (He).
Further, the air holds tiny aerosols like pollen and dust particles and contains pollutants including soot and smoke. All these different components make the air a mixture rather than an element.
An element in the simplest and primary constituent of matter. It is usually denoted by an atomic number that accounts for the number of protons in the atom nucleus.
The only way to break an element is through nuclear processes. Different elements and compounds in the air are mixed up in varying compositions.
For instance, nitrogen makes up the majority of the air at 78% and oxygen is the most abundant at 21%. Therefore, the air is not an element.
Is air a compound?
When two or more elements react chemically, they form compounds. The elements combine in fixed ratios to form strong chemical bonds that are difficult to break.
A chemical process is needed to separate compounds into their elements.
Air is a mixture of different compounds; thus, it’s not a compound. The constituents can be separated physically without needing a chemical process.
As such, air fails to meet this requirement; hence not a compound.
Air is made up of different compositions of gaseous compounds. The general composition of air by volume at 15 C and 101325 Pa is:
- Nitrogen (N2) – 78.084%
- Oxygen (O2) – 20.9476%
- Argon (Ar) 0.934%
- Carbon Dioxide (CO2) – 0.04%
Other trace elements include Ozone, Helium, Neon, Argon, and Krypton. Industrial pollutants such as sulfur dioxide, fluorine, and its compounds, and iodine and its compounds also make up the air mixture.
Is air a mixture?
To be called a mixture, the matter must have two or more elements that don’t react chemically and can be separated physically. The elements must retain their chemical characteristics within the mixture.
Air is a mixture. In a mixture, several compounds and elements combine without any chemical reaction, thus no chemical bonding.
These individual components retain their unique chemical characteristics. Further, the constituents can be separated by physical processes such as distillation.
Air is made up of two main gaseous compounds making about 99%. These are nitrogen (78%) and oxygen (21%).
Other trace compounds and elements include argon, carbon dioxide, ozone, water vapor, pollen, and many others. All these constituents can be physically separated from the air.
One of the physical techniques to separate components in the air is distillation. Here, the process takes advantage of the different boiling points.
Since the individual compounds retain their chemical characteristics in a mixture, a physical procedure can displace these compounds from the air.
Fractional distillation is a common process of extracting oxygen and nitrogen from the air. In the process, air after filtration to remove dust and other debris is cooled down to -200 degrees Celsius and becomes liquid.
Water vapor condenses and is removed. At -78.46 degrees Celsius, carbon dioxide liquefies and is removed.
At -200 degrees, the liquid air mixture enters a heated column, where three gases are extracted due to the difference in their boiling points. These are:
- Oxygen boiling point (-183.0 degrees Celsius)
- Argon boiling point (-185.8 degrees Celsius)
- Nitrogen boiling point (-195.8 degrees Celsius)
Air is a homogenous mixture of several gases, including oxygen, nitrogen, hydrogen, helium, argon, and many others.
It also contains other trace elements of pollutants, water vapor, pollen, and dust particles. All these elements and compounds don’t react chemically and retain their characteristics; thus, air cannot be a compound.
Further, the constituents of air can be separated physically through means such as distillation. Therefore, the air is a mixture