Ozone Layer

What is Ozone?

Ozone is a natural gas present within the atmosphere of our planet. Well, how is ozone formed? Three oxygen atoms form the ozone layer on the upper atmosphere of the Earth's surface. The layer of atmosphere in which the ozone layer lies is called the stratosphere. Hence, you get the ozone layer formula - O₃. The ozone structure indicates that it is quite unstable and much more reactive as compared to oxygen (O₂). It implies it can it is easy to form and decompose when interacted with other compounds. The O₃ can deplete and decompose when it collaborates with human-made compounds in the stratosphere.

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Diagram showing where the Ozone layer lies and distance between different layers in Earth's atmosphere.

On the other hand, Ozone gas also exists near the Earth's surface, in the lower atmosphere called the troposphere. Here chemical responses between air pollutants from gasoline smoke, vehicle exhaust, and other emissions create O₃ that is, however, toxic to people and plants alike.

Today this protective ozone layer is depleting because of the presence of chlorofluorocarbon compounds (CFC) in the atmosphere. These compounds mix with other gases present in the environment and enter the Earth's stratosphere. In the presence of ultraviolet rays, these agents deliver chlorine radicals in the air to produce oxygen molecule and chlorine monoxide. As a result, the ozone layer depletes. 

Element Properties

  • Symbol: O₃

  • Atomic Weight: 48

  • Solubility: 570 mg/l bij 20 °C

  • Energy: 142,3 KJ/mol (34,15 kcal/mol)

  • Melting Point: -192.2 °C

  • Boiling Point: -112 °C

  • Critical Temperature: -12,1 °C

  • Binding Degree: 116 °

  • Critical Pressure: 5460 kPa

  • Density: 2,14 kg O₃/m³ bij 0°C 1013 mbar

  • Relative Density (in air): 1,7 kg/m³

  • Electrochemical Potential: 2,07 volt

Properties of O₃

  • Ozone is a form of oxygen called a triatomic allotrope of oxygen. The molecule in the ozone structure comprises of three atoms.

  • This form of oxygen is a pale blue and irritating gas that even at low concentrations is combustible and lethal in nature.

  • O₃ absorbs solar ultraviolet radiation when naturally produced in the Earth's stratosphere in little quantities. Otherwise, the UV sunlight could lead to drastic destruction to living organisms on our planet. Ozone can control the ultraviolet range extending between 220 - 290 nm of the atmospheric spectrum.

  • Another significant property of O₃ is that it is highly reactive, especially when exposed to heat. In the presence of heat, it even decomposes back to oxygen, which is known as thermal decomposition process. This process can spontaneously happen at roughly 300 degrees Celsius. When the temperature rises, it creates an exothermic reaction that causes the breakdown of ozone to an oxygen atom as well as an oxygen molecule. 

  • The boiling point of ozone is −112 °C (−169.6 °F) that turns into violet-blue crystals on solidifying whereas its melting point is -192.2 (−314 °F).

Preparation of Ozone Layer

You might be wondering how ozone layer is formed? Don't worry; here we will clear out all your confusion regarding the preparation of ozone.

The preparation of ozone is done in a two-step reactive method in the stratosphere region of the earth's surface. Firstly, an oxygen molecule decomposes by sunlight into two oxygen atoms. Afterward, the oxygen atoms interact with another oxygen atom to form O₃.

However, is this the only way you get ozone? Definitely not, men, today can even create ozone gas. So, how is the ozone formed by us? All you require for the preparation of ozone is a machine and oxygen molecules to create ozone gas. The ozone-producing machine is called an ozonizer, which is an apparatus generally used as a water or air purifier. The O₃ in this device swoops bacteria to eliminate them. 

Scientists use a similar methodology in the laboratory for the preparation of ozone. They instead of sunlight just use a high voltage electric current. The dry oxygen is placed in an ozoniser in this process. Then a salient electric current, which is high voltage electrical current zaps through the oxygen molecule that transforms the oxygen molecule into O₃ gas.

The equation for ozone formation is as follows:

  • 3O₂ + energy = 2O₃

Importance of Ozone Layer

  • One of the most important uses of the ozone layer for our environment is that it saves every single living being on the planet from the harmful UV rays of the sun. As a shield to Earth, it protects us from physical and environmental damage that UV radiation can cause.

  • Further, human-produced ozone gas is used for water and air purification.

  • Other uses of ozone layer gas are to help eliminate any unwanted toxic substances from the environment.

  • It is suitable for various industrial purposes.

Ozone Layer Depletion

Halogen gases are the reasons behind the ozone layer depletion. Bromide, halons, Chlorofluorocarbons, hydrochlorofluorocarbons, methyl, and chloride are called ozone-depleting substances or ODS. They release at the surface, spreading all over in the air and go from the lower atmosphere to the upper atmosphere through wind transport patterns. These gases further create chlorine and/or bromine that are capable of ozone layer depletion by destroying the stratosphere in the presence of ultraviolet rays. 

Apart from the natural factors, scientists believe that somewhat stratospheric ozone is also damaging because of human actions such as human - made chemicals.

Fun Facts

  • Volcanic eruptions may shoot substances into the stratosphere, which causes an increased risk of ozone layer depletion.

  • In 1840 Schönbein first made an electrical ozone generating machine.

FAQ (Frequently Asked Questions)

Q1. How is the Ozone Hole Forming?

Answer. The leading cause of the ozone hole and ozone layer depletion is due to chemicals discharged in the atmosphere. It includes halocarbon solvents, refrigerants, and propellants. Further, naturally formed ozone-depleting substances (ODS), namely, CFCs, HCFCs, halons, etc., are also the culprits behind ozone damage. This ozone hole can destroy life on the earth, causing diseases like skin cancers, immune deficiency disorders, and eye cataracts. Further, it causes infertility in animals and negatively affects plant growth.

Q2. Where is the Ozone Layer Found?

Answer. A total of 90% of ozone exists in the stratosphere. It is the layer of atmosphere between 30 to 50 km altitude approximately. Ozone gas is a result of the chemical reaction between oxygen molecules (O₂) and sunlight in the upper atmosphere. Thus, the ozone structure has three oxygen atoms.