Ozone is a gas. Unlike many others, it is not transparent, but has a characteristic color and even 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. All because it is not an element. Ozone is an allotropic modification or a 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 pronounced 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 joins an O2 molecule. This happens during various reactions, for example, oxidation of phosphorus, electrical discharge or decomposition of peroxides, during which oxygen atoms are released.
Ozone Properties
Under normal conditions, ozone exists in the form of a gas with a molecular weight of almost 48 g / mol. He is a diamagnet, that is, he is not able to attract 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, the color of indigo is close to violet. The boiling point is 111.8 degrees Celsius. At a temperature of zero degrees, it dissolves in water (only in pure) 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, releasing free oxygen atoms. Connecting with it, it immediately ignites. The substance is capable of oxidizing almost all metals. Only platinum and gold are not amenable to its action. It destroys various organic and aromatic compounds. Upon contact with ammonia forms ammonium nitrite, destroys double carbon bonds.
Being present in the atmosphere in high concentrations, ozone decomposes spontaneously. 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. With an increase in temperature and a decrease in pressure or in contact with organic substances, the decomposition of O3 occurs faster.
Discovery story
In chemistry, ozone was not known until the 18th century. It was discovered in 1785 due to the smell that physicist Van Marum heard next to a working electrostatic machine. For another 50 years after this, gas did not appear in scientific experiments and studies.
The scientist Christian Schönbein 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 methods for producing a newly discovered gas.
Soon, other scientists joined the study of the substance. The famous physicist Nikola Tesla even built the first ozone generator in history . 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.
Atmospheric ozone
Our Earth is surrounded by an invisible shell of air - the atmosphere. Without it, life on the planet would not have been possible. Components of atmospheric air: oxygen, ozone, nitrogen, hydrogen, methane and other gases.
Ozone itself does not exist and arises only as a result of chemical reactions. Close to the surface of the Earth, it is formed due to electric discharges of lightning during a thunderstorm. In an unnatural way, it appears due to exhaust emissions from automobiles, factories, gasoline fumes, and the effects of thermal power plants.
Ozone in the lower 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 is formed 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 ozone layer of the planet, which protects it from powerful solar radiation. It absorbs approximately 98% of ultraviolet radiation with a wavelength sufficient to cause cancer and burns.
Substance use
Ozone is an excellent oxidizer and destroyer. This property has long been used to purify drinking water. The substance is detrimental to bacteria and viruses dangerous to humans, and when oxidized, it turns into harmless oxygen.
It is capable of killing even chlorine-resistant organisms. In addition, it is used to purify wastewater from environmentally harmful oil products, sulfides, phenols, etc. Such practices are distributed mainly in the United States and some European countries.
Ozone is used in medicine for disinfecting instruments, in industry with its help paper is bleached, oils are purified, various substances are obtained. The use of O3 for the purification of 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 carry, poisoning cannot be avoided. In Russia, its allowable rate is 0.1 μg / L.
When this norm is exceeded, typical signs of chemical poisoning appear, such as headache, irritation of the mucous membranes, dizziness. Ozone reduces the body's resistance to infections transmitted through the respiratory tract, and also reduces blood pressure. At gas concentrations above 8–9 μg / L, pulmonary edema and even death are possible.
At the same time, it is quite easy to recognize ozone in the air. The smell of "freshness", chlorine or "crayfish" (as Mendeleev argued) is clearly audible even with a low content of the substance.