Ozone is a gas of blue color. Properties and application of gas. Ozone in the atmosphere

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 his role in the life of the planet?

Blue gas

In chemistry, ozone does not have a separate place in the periodic table. All because he 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 it has not two but three. Therefore, its chemical formula looks like O3.

Ozone is a gas of blue color. It has a noticeable sharp smell resembling 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" - it "smells".

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 added to the O2 molecule. This occurs during various reactions, for example, oxidation of phosphorus, electric discharge or 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 a diamagnet, that is, it can not attract to a magnet, just like silver, gold or nitrogen. The density of ozone is 2.1445 g / dm3.

In solid state, ozone acquires a blue-black color, in liquid state it is indigo, close to purple. 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 perfectly mixes with liquid methane, nitrogen, fluorine, argon, and under certain conditions with oxygen.

Under the action of a number of catalysts, it is easy to oxidize, releasing free oxygen atoms. Connecting with him, immediately ignited. The substance is able to oxidize almost all metals. Only platinum and gold do not lend themselves to its action. It destroys various organic and aromatic compounds. Upon contact with ammonia, it forms ammonium nitrite, destroys the double carbon bonds.

Being present in the atmosphere in high concentrations, ozone spontaneously decomposes. In this case, heat is released and a molecule O2 is formed. The higher its concentration, the stronger the heat release reaction. With an ozone content of more than 10%, it is accompanied by an explosion. With increasing temperature and decreasing pressure or contact with organic substances, the decomposition of O3 is faster.

History of the discovery

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 the working electrostatic machine. Another 50 years after that, gas did not appear in scientific experiments and research.

Scientist Christian Schoenbane in 1840 studied the oxidation of white phosphorus. During the experiments, he managed to identify an unknown substance, which he called "ozone." The chemist took up the study of his properties and described ways of obtaining newly discovered gas.

Soon, other scientists joined the research of the substance. The famous physicist Nikola Tesla even built the first ever ozone generator. Industrial use of O3 began at the end of the XIX 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 from the air - the atmosphere. Without it, life on the planet would be impossible. Ambient air components: oxygen, ozone, nitrogen, hydrogen, methane and other gases.

Ozone itself does not exist and only appears 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. Unnatural way it appears due to emissions of car exhausts, plants, fumes of gasoline, the operation of thermal power plants.

Ozone of the lower layers of the atmosphere is called surface or tropospheric. There is also a stratospheric one. It arises under the action 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 for the onset of cancer and burns.

Application of the substance

Ozone is an excellent oxidizer and destroyer. This property has long been used to purify drinking water. The substance has a harmful effect on dangerous bacteria and viruses for humans, and itself turns into harmless oxygen during oxidation.

It is able to kill even organisms that are resistant to chlorine. In addition, it is used to purify sewage from environmentally harmful petroleum products, sulphides, phenols, etc. Such practices are prevalent mainly in the US and some European countries.

Ozone is used in medicine to disinfect tools, in the industry with its help, bleach paper, clean oils, get various substances. The use of O3 for cleaning air, water and a room is called ozonation.

Ozone and man

Despite all its useful properties, ozone can be dangerous to humans. If there is more gas in the air than a person can tolerate, poisoning can not be avoided. In Russia, its permissible norm is 0.1 μg / l.

When this limit 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. If the gas concentration is above 8-9 μg / l, pulmonary edema and even death are possible.

In this case, 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 matter.