Cryogenic release of radioactive noble gases. What is an inert gas

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What are “noble” gases

The group of noble gases includes a whole list of different chemical elements that can be ordered or combined according to their properties. Naturally, gases do not have a completely identical composition, and what they have in common is that under the simplest conditions, which in chemistry are called normal conditions, these gases have no color, taste or smell. In addition, they also have in common the fact that they have extremely low chemical reactivity.

List of "noble" gases

The list of noble gases known to mankind includes only 6 names. Among them are the following chemical elements:

Radon;
Helium;
Xenon;
Argon;
Krypton;
Neon.

Why are gases called “noble”?

As for the direct origin of the name that scientists assigned to the chemical elements described above, it was given to them because of the behavior of the atoms of the elements with other elements.

As is known, chemical elements can influence each other and exchange atoms with each other. This condition also applies to many gases. However, if we talk about the elements from the list presented above, they do not react with any other elements present in the periodic table known to us all. This led to the fact that scientists very quickly conditionally classified the gases into one group, calling it noble in honor of their “behavior.”

Other names for noble gases

It is important to note that noble gases also have other names by which scientists call them and which can also be called official

“Noble” gases are also called “Inert” or “Rare” gases

As for the second option, its origin is quite obvious, because from the entire periodic table of elements, only 6 atoms can be noted that belong to the list of noble gases. If we talk about the origin of the name “Inert,” then here you can use synonyms of this word, among which there are such concepts as “inactive” or “lacking initiative.”

Thus, all three names used for such gases are relevant and rationally selected.

Opening:

In 1893, attention was drawn to the discrepancy between the densities of nitrogen from the air and nitrogen obtained from the decomposition of nitrogen compounds: a liter of nitrogen from the air weighed 1.257 g, and that obtained chemically weighed 1.251 g. A very accurate study of the composition of the air carried out to clarify this mysterious circumstance showed that after all the oxygen and nitrogen were removed, there was a small residue (about 1%) that did not react chemically with anything.

The discovery of a new element, called argon (Greek for inactive), thus represented the “triumph of the third decimal place.” The molecular weight of argon turned out to be 39.9 g/mol.

The next inert gas to be discovered, helium (“solar”), was discovered on the Sun earlier than on Earth. This turned out to be possible thanks to the spectral analysis method developed in the 50s of the last century.

A few years after the discovery of argon and helium (in 1898), three more noble gases were isolated from the air: neon (“new”), krypton (“hidden”) and xenon (“alien”). How difficult it was to detect them can be seen from the fact that 1 m 3 of air, along with 9.3 liters of argon, contains only 18 ml of neon, 5 ml of helium, 1 ml of krypton and 0.09 ml of xenon.

The last inert gas, radon, was discovered in 1900 while studying certain minerals. Its content in the atmosphere is only 6-10 -18% by volume (which corresponds to 1-2 atoms per cubic centimeter). It has been estimated that the entire earth's atmosphere contains only 374 liters of radon.

Physical properties:

All noble gases are colorless and consist of monatomic molecules. The separation of inert gases is based on the difference in their physical properties.

Inert gases are colorless and odorless. They are present in small quantities in the air. Inert gases are not poisonous. However, an atmosphere with an increased concentration of inert gases and a corresponding decrease in oxygen concentration can have a suffocating effect on a person, including loss of consciousness and death. There are known cases of death due to argon leaks.


Melting point, °C
Boiling point, °C

The amount of heat required to transfer a substance from a solid to a liquid state is called the heat of fusion, and to transfer from a liquid to a vapor state is called the heat of evaporation. Both quantities are usually referred to as transitions occurring under normal pressure. For inert gases they have the following values (kcal/g-atom):


Heat of Melting
Heat of vaporization

Below are compared critical temperatures inert gases and those pressures that are necessary and sufficient for their transfer at these temperatures from a gaseous state to a liquid state, - critical pressures:


Critical temperature, °C
Critical pressure, atm

This is interesting :

The question of the atomicity of the argon molecule was resolved using kinetic theory. According to it, the amount of heat that needs to be expended to heat a gram-molecule of a gas by one degree depends on the number of atoms in its molecule. At constant volume, a gram-molecule of a monatomic gas requires 3 feces, diatomic - 5 cal. For argon the experiment gave 3 feces, which indicated the monoatomic nature of its molecule. The same applies to other inert gases.

Helium was the last gas to be converted into a liquid and solid state. In relation to it, there were special difficulties due to the fact that as a result of expansion at ordinary temperatures, helium does not cool, but heats up. Only below -250 °C does it begin to behave “normally”. It follows that the usual liquefaction process could be applied to helium only after it had been very strongly cooled beforehand. On the other hand, the critical temperature of helium is extremely low. Due to these circumstances, favorable results when working with helium were obtained only after mastering the technique of operating with liquid hydrogen, using the evaporation of which only it was possible to cool helium to the required temperatures. It was possible to obtain liquid helium for the first time in 1908, solid helium-V1926

Chemical properties:

Inert gases are characterized by a complete (He, Ne, Ar) or almost complete (Kr, Xe, Rn) lack of chemical activity. In the periodic table they form a special group (VIII). Soon after the discovery of inert gases, the new group they formed in the periodic table was called zero, in order to emphasize the zero valency of these elements, i.e., their lack of chemical activity. This name is often used at the present time, however, in essence of the periodic law, it is more correct to consider the group of inert gases as the eighth group, since the corresponding periods do not begin with these elements, but end.

The absence of complete chemical inertness in heavy inert gases was discovered only in 1962. It turned out that they are capable of combining with the most active metalloid - fluorine (and only with it). Xenon (and radon) react quite easily, krypton much more difficult. XeF 2 , XeF 4 , XeF 6 and low-stable KrF 2 were obtained. All of them are colorless volatile crystalline substances.

Xenon difluoride(XeF 2) - is slowly formed under the influence of daylight on a mixture of Xe and F 2 at zero conditions. It has a characteristic nauseating odor. The formation of a molecule requires excitation of the xenon atom from 5s 2 5p 6 to the nearest divalent state 5s 2 5p 5 s 1 - 803 kJ/mol, to 5s 2 5p 5 6p 1 -924 kJ/mol, 25s 2 5p 1 6d 1 - 953 kJ/ mole.

Xe+F 2 →XeF 2

0.15 mol/l dissolves in water. The solution is a very strong oxidizing agent. The solution decomposes according to the following scheme:

XeF 2 +H 2 O →HF+Xe+O 2 (the process occurs faster in an alkaline environment, slower in an acidic environment).

Xenontetrafluoride- formed from simple substances, the reaction is highly exothermic, and is the most stable of all fluorides.

XeF 4 +2Hg=2HgF 2 +Xe

XeF 4 +Pt=PtF 4 +Xe

Qualitative reaction to xenon tetrafluoride :

XeF 4 +4KI=4KF+2I 2 ↓+Xe

Xenon tetrafluoride decomposes according to the following schemes:

3Xe 4+ →Xe 6+ +2Xe 0 (in acidic medium).

Xe 4+ →Xe 0 +Xe 8+ (in an alkaline medium).

Xenon hexafluoride is colorless, known in 3 crystalline modifications. At 49 ℃, turning into a yellow liquid, when hardening it becomes discolored again. The vapors are pale yellow in color. Explosively decomposes. Under the influence of moist air hydrolyze:

XeF 6 +H 2 O→2HF+OXeF 4

OXeF 4 is a colorless liquid, less reactive than XeF 6. Forms crystalline hydrates with alkali metal fluorides, for example: KF∙OXeF 4

Further hydrolysis can produce xenon trioxide:

XeF 6 +3H 2 O→XeO 3 +6HF

XeO 3 is a colorless explosive substance that diffuses in air. It disintegrates explosively, but when gently heated at 40 degrees Celsius, the reaction occurs:

2XeO 3 →2Xe+3O 2

There is an acid that formally corresponds to this oxide - H 2 XeO 4. There are salts corresponding to this acid: MHXeO 4 or MH 5 XeO 6, an acid (M - from sodium to cesium) corresponding to the last salt was obtained:

3XeF 4 +6Ca(OH) 2 →6CaF 2 ↓+Xe+2H 2 XeO 6

In a strongly alkaline environment, Xe 6+ dismutates:

4Xe 6+ →Xe 0 +3Xe 8+

Krypton difluoride- volatile, colorless crystals , a chemically active substance. At elevated temperatures it decomposes into fluorine krypton . It was first obtained by the action of an electric discharge on a mixture of substances, at -188℃:

F 2 +Kr→KrF 2

Decomposes with water according to the following scheme:

2KrF 2 +2H 2 O→O 2 +4HF+2Kr

Application of inert gases:

Inert gases find quite a variety of practical applications. In particular, the role of helium in obtaining low temperatures is extremely important, since liquid helium is the coldest of all liquids. Artificial air, in which nitrogen is replaced by helium, was first used to ensure the breathing of divers. The solubility of gases increases greatly with increasing pressure, therefore, when a diver descends into water and is supplied with ordinary air, the blood dissolves more nitrogen than under normal conditions. During ascent, when the pressure drops, dissolved nitrogen begins to be released and its bubbles partially clog small blood vessels, thereby disrupting normal blood circulation and causing attacks of “caisson sickness.” Thanks to the replacement of nitrogen with helium, painful effects are sharply weakened due to the much lower solubility of helium in the blood, which is especially noticeable at high pressures. Working in an atmosphere of “helium” air allows divers to descend to great depths (over 100 m) and significantly extend their stay under water.

Since the density of such air is approximately three times less than that of normal air, it is much easier to breathe. This explains the great medical importance of helium air in the treatment of asthma, suffocation, etc., when even short-term relief of a patient’s breathing can save his life. Similar to helium, “xenon” air (80% xenon, 20% oxygen) has a strong narcotic effect when inhaled, which can be used medically.

Neon and argon are widely used in the electrical industry. When an electric current passes through glass tubes filled with these gases, the gas begins to glow, which is used to design illuminated inscriptions.

High-power neon tubes of this type are especially suitable for lighthouses and other signaling devices, since their red light is little blocked by fog. The color of the helium glow changes from pink through yellow to green as its pressure in the tube decreases. Ar, Kr and Xe are characterized by different shades of blue.

Argon (usually mixed with 14% nitrogen) is also used to fill electric lamps. Due to their significantly lower thermal conductivity, krypton and xenon are even better suited for this purpose: electric lamps filled with them provide more light with the same energy consumption, withstand overload better and are more durable than conventional ones.

Editor: Galina Nikolaevna Kharlamova

- (a. inert gasses; n. Inertgase, Tragergase; f. gaz inertes; i. gases inertes) noble, rare gases, monatomic gases without color and odor: helium (He), neon (Ne) ... Geological encyclopedia

- (noble gases, rare gases) elements ch. subgroups of group VIII periodic. systems of elements. Irradiation includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radioactivity. radon (Rn). In nature, i.g. are present in the atmosphere, Not... ... Physical encyclopedia

Big Encyclopedic Dictionary

Noble gases- the same as noble gases... Russian encyclopedia of labor protection

Noble gases- INERT GASES, the same as noble gases. ... Illustrated Encyclopedic Dictionary

INERT [ne], aya, oh; ten, tna. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

inert gases- Elements of group VIII Periodic. systems: He, Ne, Ar, Kr, Xe, Rn. I. g. differ chemically. inertia, which is explained by the stable external an electronic shell, on which Ne has 2 electronics, the rest have 8 electronics. I. g. have a high potential... Technical Translator's Guide

Group → 18 ↓ Period 1 2 Helium ... Wikipedia

inert gases- elements of Group VIII of the Periodic Table: He, Ne, Ar, Kr, Xe, Rn. Noble gases are characterized by chemical inertness, which is explained by a stable outer electron shell, on which He has 2 electrons, the rest have 8... ... Encyclopedic Dictionary of Metallurgy

Noble gases, rare gases, chemical elements forming the main subgroup of the 8th group of the periodic system of Mendeleev: Helium He (atomic number 2), Neon Ne (10), Argon Ar (18), Krypton Kr (36), Xenon Xe (54) and Radon Rn (86). From… … Great Soviet Encyclopedia

Books

Set of tables. Chemistry. Nonmetals (18 tables), . Educational album of 18 sheets. Art. 5-8688-018 Halogens. Chemistry of halogens. Sulfur. Allotropy. Chemistry of sulfur. Sulfuric acid. Chemistry of nitrogen. Nitrogen oxides. Nitric acid is an oxidizing agent. Phosphorus.…
Inert gases, Fastovsky V.G.. The book discusses the basic physical and physico-chemical properties of the inert gases helium, neon, argon, krypton and xenon, as well as their areas of application in chemical, metallurgical,…

- (a. inert gasses; n. Inertgase, Tragergase; f. gaz inertes; i. gases inertes) noble, rare gases, monatomic gases without color and odor: helium (He), neon (Ne) ... Geological encyclopedia

Big Encyclopedic Dictionary

Noble gases- the same as noble gases... Russian encyclopedia of labor protection

Noble gases- INERT GASES, the same as noble gases. ... Illustrated Encyclopedic Dictionary

INERT [ne], aya, oh; ten, tna. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

GROUP 0. NOBLE (INERT) GASES HELIUM, NEON, ARGON, KRYPTON, XENON, RADON Atoms of elements of group zero have a completely completed outer electron shell, which corresponds to the most stable electronic configuration, and for... ... Collier's Encyclopedia

Books

Set of tables. Chemistry. Nonmetals (18 tables), . Educational album of 18 sheets. Art. 5-8688-018 Halogens. Chemistry of halogens. Sulfur. Allotropy. Chemistry of sulfur. Sulfuric acid. Chemistry of nitrogen. Nitrogen oxides. Nitric acid is an oxidizing agent. Phosphorus.…
Inert gases, Fastovsky V.G.. The book discusses the basic physical and physico-chemical properties of the inert gases helium, neon, argon, krypton and xenon, as well as their areas of application in chemical, metallurgical,…

Cryogenic release of radioactive noble gases. What is an inert gas

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