Introduction
Perhaps one of the most abundant of any chemical mixtures, air is so vital to the existence of many living things and various chemical processes. The earth is able to sustain living things anywhere there is air. One might really take air for granted, but this mixture holds a very high value in the world of chemistry which is why it would be nice to learn about it.
In this presentation, we will look at what air is made of. We will also try to see the chemical quantity and composition of various elements in air. One important thing to learn from this presentation is the nature of reaction of the elements in air and how each tries to retain their individual chemical properties.
Chemical components of air
The air we breath is made up of many gases that combine together. Hence, air is viewed as a mixture of several gases. The main chemical components of air are nitrogen and oxygen. These two accounts for for more than 90% volume of air any where. Other gases are present in air but in really minute quantities.
About 1% volume of other gases that make up air includes the rare gases like neon and xenon. Carbon dioxide is also present in air but makes up an insignificant volume - about 0.03%. Being specific here, air contains 78% of nitrogen and 21% of oxygen. The other gases, humidity, dust and other components make up about 1% of the air in our environment. You can take a look at the pie chart below which maps the chemical components of air and their percentage volume.
Remember that the percentage or volume of each component above is not universal. Air differs from place to place due to a lot of factors like altitude, relative humidity, temperature and other factors. However, the deviation in percentage of components is always very slight.
Now consider one of the most important components of air - oxygen
Oxygen in air
The most reactive component of air is oxygen which makes up about 21% of the chemical volume in air. Atmospheric oxygen is vital for many chemical processes and the sustenance of living things. When living organisms breath in air, oxygen is the element that helps to sustain life. Living things breath in oxygen and release carbon dioxide during respiration.
During respiration, oxygen in air is captured through the lungs from where it moves to combine with the blood of that organism. It is then carried by the blood and circulated throughout the body, allowing various tissues and organs of the living thing to stay alive and carry out their functions. A lack of oxygen in air over a short period of time can lead to instant death of the organism.
Another important chemical reaction that involves air and oxygen is combustion. The burning of substances in air is usually actively supported by the presence of atmospheric oxygen. This chemical combination of a burning material and air often results in the formation of oxides. Consider the following chemical reactions:
- Combustion of Candle wax: Candle wax is usually composed of any of the hydrocarbons. When a candle wax burns in air, it decomposes into the various elements that make up the hydrocarbon. In the process, oxygen combines with those elements to produce carbon IV oxide and water.
The candle wax that burns in air might come from any of the hydrocarbon families like alkenes, alkanes and alkynes. Consider the chemical reaction below of a candle wax from the alkane family - Octane.
- Rusting of Metals: Another important chemical reaction that involves atmospheric oxygen is the rusting of metals. Unlike burning which is always fast, rusting takes place over a long period of time. The oxygen in air mixes with water or humidity and attacks an exposed metal. Over time, the metal begins to rust. Since this is a process that usually takes a really long time, carbon (iv) oxide accelerates the entire process.
A very good example of rusting in the presence of atmospheric oxygen is the rusting of iron. In this chemical process, oxygen in air combines with water and attacks iron. This reaction leads to the oxidation of iron to Iron (III) oxide. Check the chemical equation of the reaction below.
Conclusion
Air contains two major elements in Oxygen and Nitrogen. We have seen the volume composition of each element in the mixture. The most reactive of the two is oxygen even though Nitrogen has a larger composition volume. Atmospheric oxygen is crucial to life as it supports respiration through which living organisms obtain oxygen.
Although oxygen is not super reactive as a constituent of air, it readily combines with other elements in different chemical reactions in which air must be present. Examples shown above includes combustion of various materials in air and rusting.
Disclaimer: Thumbnail is from Pixabay. Pie Chart is from Meta Chart. All other Images are mine.