The phrase "ozone layer", which became famous in the 70s. last century, has long been sore. However, few people really understand what this concept means and what is the danger of the destruction of the ozone layer. An even greater mystery for many is the structure of the ozone molecule, but it is directly related to the problems of the ozone layer. Let's learn more about ozone, its structure and its use in industry.
What is ozone?
Ozone, or, as it is also called, active oxygen, is a gas of azure color with a sharp metallic smell.
This substance can exist in all three states of aggregation: gaseous, solid and liquid.
Moreover, in nature, ozone is found only in the form of gas, forming the so-called ozone layer. It is because of its azure color that the sky appears blue.
What does the ozone molecule look like
Ozone got its nickname "active oxygen" because of its similarity to oxygen. So the main active chemical element in these substances is oxygen (O). However, if the oxygen molecule contains 2 of its atoms, then the ozone molecule (formula - O 3 ) consists of 3 atoms of this element.
Due to this structure, the properties of ozone are similar to oxygen, but more pronounced. In particular, like O 2 , O 3 is the strongest oxidizing agent.
The most important difference between these "related" substances, which is vital for everyone to remember, is the following: you cannot breathe ozone, it is toxic and if inhaled it can damage the lungs or even kill a person. At the same time, O 3 is perfect for purifying air from toxic impurities. By the way, precisely because of this, it is so easy to breathe after rain: ozone oxidizes the harmful substances contained in the air, and it is purified.
The ozone molecule model (consisting of 3 oxygen atoms) is a bit like an image of an angle, and its size is 117 °. This molecule has no unpaired electrons; therefore, it is diamagnetic. In addition, it has a polarity, although it consists of atoms of one element.
Two atoms of this molecule are firmly bonded to each other. But the connection with the third is less reliable. For this reason, the ozone molecule (photo of the model can be seen below) is very fragile and disintegrates soon after formation. As a rule, oxygen is released during any decomposition reaction of O 3 .
Due to the instability of ozone, it cannot be harvested and stored, as well as transported like other substances. For this reason, its production is more expensive than other substances.
Moreover, the high activity of O 3 molecules allows this substance to be the strongest oxidizing agent, more powerful than oxygen, and safer than chlorine.
If the ozone molecule is destroyed and O 2 is released , this reaction is always accompanied by the release of energy. At the same time, for the reverse process to occur (the formation of O 3 from O 2 ), it is necessary to spend it no less.
In the gaseous state, the ozone molecule decomposes at a temperature of 70 ° C. If it is raised to 100 degrees or more, the reaction will accelerate significantly. The presence of impurities also accelerates the decay period of ozone molecules.
O3 Properties
Whichever of the three states ozone is in, it remains blue. The harder the substance, the richer and darker this shade.
Each ozone molecule weighs 48 g / mol. It is heavier than air, which helps to separate these substances among themselves.
O 3 is able to oxidize almost all metals and non-metals (except gold, iridium and platinum).
Also, this substance can participate in the combustion reaction, however, this requires a higher temperature than for O 2 .
Ozone is capable of dissolving in H 2 O and freons. In the liquid state, it can be mixed with liquid oxygen, nitrogen, methane, argon, carbon tetrachloride and carbon dioxide.
How an ozone molecule is formed
O 3 molecules are formed by attaching free oxygen atoms to oxygen molecules. They, in turn, appear due to the splitting of other O 2 molecules due to exposure to electric discharges, ultraviolet rays, fast electrons and other high-energy particles. For this reason, the specific smell of ozone can be felt near sparkling electrical appliances or lamps that emit ultraviolet light.
On an industrial scale, O 3 is isolated using electric ozone generators or ozonizers. In these devices, a high-voltage electric current is passed through a gas stream in which O 2 is located, whose atoms serve as the “building material” for ozone.
Sometimes pure oxygen or ordinary air is launched into these devices. The purity of the ozone depends on the purity of the starting product. So, medical O 3 , intended for the treatment of wounds, is extracted only from chemically pure O 2 .
History of the discovery of ozone
Having understood how the ozone molecule looks and how it is formed, it is worth getting acquainted with the history of this substance.
It was first synthesized by the Dutch researcher Martin Van Marum in the second half of the 18th century. The scientist noticed that after passing electric sparks through a container with air, the gas in it changed its properties. At the same time, Van Marum did not understand that he isolated molecules of a new substance.
But his German colleague by the name of Scheinbein, trying to decompose H 2 O into H and O 2 using electricity, drew attention to the evolution of a new gas with a pungent odor. After conducting a lot of research, the scientist described the substance he discovered and gave him the name “ozone” in honor of the Greek word “smell”.
The ability to kill fungi and bacteria, as well as reduce the toxicity of harmful compounds, which had an open substance, interested many scientists. 17 years after the official discovery of O 3, Werner von Siemens designed the first apparatus to synthesize any amount of ozone. And after 39 years, the brilliant Nikola Tesla invented and patented the world's first ozone generator.
It was this apparatus that, after 2 years, was first used in France in wastewater treatment plants for drinking water. With the beginning of the XX century. Europe begins to switch to the ozonation of drinking water for its purification.
The Russian empire first used this technique in 1911, and after 5 years, almost 4 dozen installations for purifying drinking water using ozone were equipped in the country.
Today, ozonation of water is gradually replacing chlorination. So, 95% of all drinking water in Europe is purified using O 3 . This technique is also very popular in the United States. In the CIS, it is still under study, because although this procedure is safer and more convenient, it is more expensive than chlorination.
Ozone Applications
In addition to water purification, O 3 has a number of other applications.
- Ozone is used as a bleach in the manufacture of paper and fabric.
- Active oxygen is used to disinfect wines, as well as to accelerate the aging process of cognacs.
- With the help of O 3 various vegetable oils are refined.
- Very often, this substance is used to process perishable products, such as meat, eggs, fruits and vegetables. With this procedure, there are no chemical traces, as when using chlorine or formaldehyde, and the products can be stored for much longer.
- Ozone sterilizes medical equipment and clothing.
- Also purified O 3 is used for various medical and cosmetic procedures. In particular, with its help in dentistry, the oral cavity and gums are disinfected, and various diseases (stomatitis, herpes, oral candidiasis) are treated. In European countries, O 3 is very popular for wound disinfection.
- In recent years, portable home appliances for filtering air and water with ozone have gained immense popularity.
Ozone layer - what is it?
At a distance of 15-35 km above the Earth’s surface is the ozone layer, or, as it is also called, the ozonosphere. At this point, concentrated O 3 serves as a kind of filter for harmful solar radiation.
Where does such an amount of matter come from if its molecules are unstable? It is not difficult to answer this question if we recall the model of the ozone molecule and the method of its formation. So, oxygen, consisting of 2 oxygen molecules, getting into the stratosphere, is heated there by the sun's rays. This energy is enough to split O 2 into atoms, from which O 3 is formed. At the same time, the ozone layer not only uses part of the solar energy, but also filters it, absorbs dangerous ultraviolet.
It was said above that ozone is dissolved by freons. These gaseous substances (used in the manufacture of deodorants, fire extinguishers and refrigerators), once in the atmosphere, affect ozone and contribute to its decomposition. As a result of this, holes arise in the ozonosphere through which unfiltered sun rays fall on the planet, which destructively affect living organisms.
Having considered the features and structure of ozone molecules, we can conclude that this substance, although dangerous, is very useful for humanity, if used correctly.