Ozone is a gas. Unlike many others, it is not transparent, but has a characteristic color and even a smell. It is present in our atmosphere and is one of its most important components. What is the density of ozone, its mass and other properties? What is its role in the life of the planet?
Blue gas
In chemistry, ozone does not have a separate place in the periodic table. This is because it is not an element. Ozone is an allotropic modification or variation of oxygen. As in O2, its molecule consists only of oxygen atoms, but has not two, but three. Therefore, its chemical formula looks like O3.
Ozone is a blue gas. It has a distinct pungent odor reminiscent of chlorine if the concentration is too high. Do you remember the smell of freshness in the rain? This is ozone. Thanks to this property, it got its name, because from the ancient Greek language "ozone" is "smell".
The gas molecule is polar, the atoms in it are connected at an angle of 116, 78°. Ozone is formed when a free oxygen atom is attached to an O2 molecule. It happens inthe time of various reactions, for example, the oxidation of phosphorus, an electric discharge, or the decomposition of peroxides, during which oxygen atoms are released.
Properties of ozone
Under normal conditions, ozone exists as a gas with a molecular weight of almost 48 g/mol. It is diamagnetic, that is, it is not able to be attracted to a magnet, just like silver, gold or nitrogen. The density of ozone is 2.1445 g/dm³.
In the solid state, ozone acquires a bluish-black color, in the liquid state, an indigo color close to violet. The boiling point is 111.8 degrees Celsius. At a temperature of zero degrees, it dissolves in water (only in pure water) ten times better than oxygen. It mixes well with liquid methane, nitrogen, fluorine, argon, and under certain conditions with oxygen.
Under the action of a number of catalysts, it is easily oxidized, while releasing free oxygen atoms. Connecting with it, it immediately ignites. The substance is able to oxidize almost all metals. Only platinum and gold are not amenable to its action. It destroys various organic and aromatic compounds. Forms ammonium nitrite upon contact with ammonia, destroys double carbon bonds.
Present in the atmosphere in high concentrations, ozone spontaneously decomposes. In this case, heat is released and an O2 molecule is formed. The higher its concentration, the stronger the heat release reaction. When the ozone content is more than 10%, it is accompanied by an explosion. By increasing temperature and decreasing pressure, or by contact withOrganic substances decompose O3 faster.
Discovery history
In chemistry, ozone was not known until the 18th century. It was discovered in 1785 thanks to the smell that the physicist Van Marum heard next to a working electrostatic machine. Another 50 years after that, the gas did not appear in scientific experiments and research.
Scientist Christian Schonbein in 1840 studied the oxidation of white phosphorus. During the experiments, he managed to isolate an unknown substance, which he called "ozone". The chemist came to grips with the study of its properties and described how to obtain a newly discovered gas.
Soon, other scientists joined the research of the substance. The famous physicist Nikola Tesla even built the first ever ozone generator. The industrial use of O3 began at the end of the 19th century with the advent of the first installations for supplying drinking water to homes. The substance was used for disinfection.
Ozone in the atmosphere
Our Earth is surrounded by an invisible shell of air - the atmosphere. Without it, life on the planet would be impossible. Components of atmospheric air: oxygen, ozone, nitrogen, hydrogen, methane and other gases.
Ozone does not exist by itself and only occurs as a result of chemical reactions. Close to the surface of the Earth, it is formed due to electrical discharges of lightning during a thunderstorm. Unnaturally, it appears due to exhaust emissions from cars, factories, gasoline fumes, and thermal power plants.
Ozone of the lower layers of the atmosphere is called surface or tropospheric. There is also a stratospheric one. It occurs under the influence of ultraviolet radiation coming from the sun. It forms at a distance of 19-20 kilometers above the surface of the planet and stretches to a height of 25-30 kilometers.
Stratospheric O3 forms the planet's ozone layer, which protects it from powerful solar radiation. It absorbs approximately 98% of ultraviolet radiation with a wavelength sufficient to cause cancer and burns.
Using a substance
Ozone is an excellent oxidizer and destroyer. This property has long been used to purify drinking water. The substance has a detrimental effect on bacteria and viruses that are dangerous to humans, and when oxidized, it turns into harmless oxygen.
It can kill even chlorine-resistant organisms. In addition, it is used to purify wastewater from environmentally harmful oil products, sulfides, phenols, etc. Such practices are common mainly in the United States and some European countries.
Ozone is used in medicine to disinfect instruments, in industry it is used to bleach paper, purify oils, and obtain various substances. The use of O3 to purify air, water and premises is called ozonation.
Ozone and man
Despite all its beneficial properties, ozone can be dangerous to humans. If there is more gas in the air than a person can tolerate, poisoning cannot be avoided. In Russia, its permissible normis 0.1 µg/L.
When this rate is exceeded, typical signs of chemical poisoning appear, such as headache, irritation of mucous membranes, dizziness. Ozone reduces the body's resistance to infections transmitted through the respiratory tract, and also reduces blood pressure. Gas concentrations above 8–9 µg/L can lead to pulmonary edema and even death.
At the same time, it is quite easy to recognize ozone in the air. The smell of "freshness", chlorine or "crayfish" (as Mendeleev claimed) is clearly audible even with a low content of the substance.
