What substances does helium consist of? Technical helium - application in science and industry. Transport and storage

Exists three main sources of helium:

• from helium-containing natural gases
• from minerals
• out of thin air

Production of helium from natural gas

The main method for obtaining helium is the method of fractional condensation from natural helium-containing gases, i.e. deep cooling method. Moreover, its characteristic property is used - the lowest boiling point compared to known substances. This makes it possible to condense all gases associated with helium, primarily methane and nitrogen. The process is usually carried out in two stages:

• isolation of the so-called raw helium (concentrate containing 70-90% He)
• purification to obtain commercially pure helium.

The figure below shows one of the installation schemes for extracting helium from natural gas.

The gas is compressed to 25 atmospheres and enters the plant under this pressure. Cleaning from (CO 2) and partial dehydration of the gas is carried out in scrubbers, which are irrigated with a solution containing 10-20% monoethanolamine, 70-80% diethylene glycol and 5-10% water. After the scrubbers, 0.003-0.008% carbon dioxide CO 2 remains in the gas, and the dew point does not exceed 5°C. Further drying is carried out in adsorbers with silica gel, where a dew point temperature of -45°C is reached.

Under a pressure of about 20 atmospheres, clean dry gas enters the preliminary heat exchanger 1, where it is cooled to -28 ° C by reverse gas flows. In this case, condensation of heavy hydrocarbons occurs, which are separated in the separator 2. In the ammonia cooler 3, the gas is cooled to -45 ° C, the condensate is separated in the separator 4. In the main heat exchanger 5, the gas temperature decreases to -110 ° C, resulting in the condensation of a significant part of methane. The vapor-liquid mixture (about 20% liquid) is throttled to a pressure of 12 atmospheres into the first counterflow condenser 6, at the outlet of which the vapor-gas mixture is enriched with helium up to 3%. The condensate formed in the tubes flows into the stripping section, on the plates of which the helium dissolved in it is removed from the liquid, which joins the vapor-gas flow.

The liquid is throttled up to 1.5 atmospheres into the annular space of the condenser, where it serves as a refrigerant. The steam formed here is removed through heat exchangers 5 and 1. The vapor-gas mixture leaving the condenser 6 and containing up to 3% He, under a pressure of 12 atmospheres, goes to the second counterflow condenser 7, which consists of two parts: in the lower part there is a coil heat exchanger, in in the tubes of which the bottom liquid, throttled from 12 to 1.5 atmospheres, evaporates, and in the upper part - a straight-tube heat exchanger, in the annular space of which nitrogen boils at a temperature of -203 ° C and a pressure of 0.4 atmospheres. As a result of condensation of the components of the gas mixture in the lower part of apparatus 7, the gas is enriched with helium up to 30-50%, and in the upper part - up to 90-92%.

Raw helium of this composition under a pressure of 11-12 atmospheres enters the heat exchangers, where it is heated and removed from the plant. Since natural gas contains small impurities of hydrogen, the concentration of hydrogen in raw helium increases to 4-5%. Hydrogen removal is carried out by catalytic hydrogenation followed by gas drying in adsorbers with silica gel. Raw helium is compressed to 150-200 atmospheres by a membrane compressor 8, cooled in a heat exchanger 9 and enters a once-through coil condenser 10 cooled by nitrogen boiling under vacuum. The condensate (liquid) is collected in the separator 11 and periodically removed, and the uncondensed gas containing approximately 98% He goes to the adsorber 12 with activated carbon cooled with liquid nitrogen. The helium leaving the adsorber contains impurities less than 0.05% and enters the cylinders 13 as a product.

Natural gases are especially rich in helium in the United States, which determines the widespread use of helium in this country.

Obtaining helium from minerals

Another source of helium are some radioactive minerals containing uranium, thorium and samarium:

• slanders
• fergusonite
• samarskite
• gadolinite
• monazite
• thorianite

In particular monazite sands, a large deposit of which is in Travancore (India): the monazites of this deposit contain about 1 cm 3 of helium per 1 g of ore.

To obtain helium from a monocyte, it is necessary to heat the monocyte in a closed vessel to 1000°C. Helium is released along with carbon dioxide (CO 2 ), which is then absorbed into the sodium hydroxide solution (NaOH). The tail gas contains 96.6% He. Further purification is carried out at 600°C on magnesium metal to remove nitrogen, and then at 580°C on calcium metal to remove the remaining impurities. The production gas contains over 99.5% He. About 80 m 3 of pure helium can be obtained from 1000 tons of monazite sand. Such the method of obtaining helium is not of technical and industrial interest..

Getting helium from the air

There is a small amount of helium in the air, from which it can be obtained as a by-product in the production of oxygen and nitrogen from air, described in the article "". In industrial distillation columns for air separation over liquid nitrogen, the remaining gaseous mixture of neon and helium is collected. The figure below shows Claude's apparatus specially adapted to separate such a mixture.

The gas leaving the apparatus through valve D is cooled in coil S, which is poured with liquid nitrogen from T to condense the residual nitrogen. If valve R is opened a little, a mixture containing very little nitrogen is obtained. With this method of industrial production of helium, in addition to the difficulty that lies in the need to process a large number of air, there is another additional difficulty - the need separation of helium from neon. This separation can be carried out with liquid hydrogen, in which the neon solidifies, or with the adsorption of neon on activated carbon cooled with liquid nitrogen.

Obtaining helium from air is impractical due to its small amount - 0.00046% by volume or 0.00007% by weight. Calculations show that the cost of one cubic meter of helium extracted from the air will be thousands of times higher than when it is extracted from natural gases. Such a high cost, of course, excludes the possibility of industrial separation of helium from the air.

For example: To produce 1 cubic meter of helium, you need to allocate 116 tons of nitrogen.

Helium(lat. Helium), symbol Not, chemical element Group VIII periodic system, refers to inert gases; serial number 2, atomic mass 4.0026; colorless and odorless gas. Natural Helium consists of 2 stable isotopes: 3 He and 4 He (the content of 4 He sharply prevails).

Historical reference. Helium was first discovered not on Earth, where it is scarce, but in the atmosphere of the Sun. In 1868, the Frenchman J. Jansen and the Englishman J. N. Lockyer studied the composition of solar prominences spectroscopically. The images they received contained a bright yellow line (the so-called D3 line) that could not be attributed to any of the elements known at the time. In 1871, Lockyer explained its origin by the presence of a new element on the Sun, which they called helium (from the Greek helios - Sun). On Earth, Helium was first isolated in 1895 by the Englishman W. Ramsay from the radioactive mineral cleveite. The same line appeared in the spectrum of the gas released during heating of kleveite.

Distribution of helium in nature. There is little Helium on Earth: 1 m 3 of air contains only 5.24 cm 3 of Helium, and each kilogram of terrestrial material contains 0.003 mg of Helium. In terms of prevalence in the Universe, Helium ranks second after hydrogen: Helium accounts for about 23% of the cosmic mass.

On Earth, Helium (more precisely, the isotope 4He) is constantly formed during the decay of uranium, thorium and other radioactive elements (total in earth's crust contains about 29 radioactive isotopes producing 4He).

Approximately half of all helium is concentrated in the earth's crust, mainly in its granite shell, which accumulated the main reserves of radioactive elements. The content of helium in the earth's crust is small - 3·10 -7% by weight. Helium accumulates in free gas accumulations of the bowels and in oil; such deposits reach an industrial scale. The maximum concentrations of Helium (10-13%) were found in free gas accumulations and gases from uranium mines and (20-25%) in gases released spontaneously from groundwater. The older the age of gas-bearing sedimentary rocks and the higher the content of radioactive elements in them, the more Helium is in the composition of natural gases. Volcanic gases are usually characterized by a low content of Helium.

Helium production on an industrial scale is carried out from natural and petroleum gases of both hydrocarbon and nitrogen composition. According to the quality of raw materials, helium deposits are divided into: rich (He content > 0.5% by volume); ordinary (0.10-0.50) and poor (<0,10). В СССР природный Гелий содержится во многих нефтегазовых месторождениях. Значительные его концентрации известны в некоторых месторождениях природного газа Канады, США (штаты Канзас, Техас, Нью-Мексико, Юта).

Isotopes, atom and molecule of Helium. In natural helium of any origin (atmospheric, from natural gases, from radioactive minerals, meteorite, etc.), the isotope 4 He predominates. The content of 3 He is usually low (depending on the source of Helium, it ranges from 1.3·10 -4 to 2·10 -8%) and only in Helium isolated from meteorites does it reach 17-31.5%. The rate of formation of 4 He during radioactive decay is low: in 1 ton of granite containing, for example, 3 g of uranium and 15 g of thorium, 1 mg of Helium is formed in 7.9 million years; however, since this process proceeds constantly, during the existence of the Earth, it should have ensured the content of Helium in the atmosphere, lithosphere and hydrosphere, which is much higher than the present one (it is about 5 10 14 m 3). Such a shortage of helium is explained by its constant volatilization from the atmosphere. Light atoms of Helium, falling into the upper layers of the atmosphere, gradually acquire a speed higher than the second cosmic one and thereby get the opportunity to overcome the forces of the earth's gravity. The simultaneous formation and volatilization of helium lead to the fact that its concentration in the atmosphere is practically constant.

The 3 He isotope, in particular, is formed in the atmosphere during the β-decay of the heavy hydrogen isotope - tritium (T), which, in turn, arises during the interaction of cosmic radiation neutrons with atmospheric nitrogen:

14 7 N + 3 0 n → 12 6 C + 3 1 T.

The nuclei of the 4 He atom (consisting of 2 protons and 2 neutrons), called alpha particles or helions, are the most stable among the compound nuclei. The binding energy of nucleons (protons and neutrons) in 4 He has a maximum value compared to the nuclei of other elements (28.2937 MeV); therefore, the formation of 4 He nuclei from hydrogen nuclei (protons) 1 H is accompanied by the release of a huge amount of energy. It is believed that this nuclear reaction:

4 1 H = 4 He + 2β + + 2n

[simultaneously with 4 He, two positrons (β +) and two neutrinos (ν) are formed] serves as the main source of energy for the Sun and other stars similar to it. Thanks to this process, very significant reserves of Helium accumulate in the Universe.

Physical properties of Helium. Under normal conditions, helium is a monatomic gas, colorless and odorless. Density 0.17846 g/l, t bale -268.93°С, t pl -272.2°С. Thermal conductivity (at 0°C) 143.8 10 -3 W / (cm K) . The radius of the Helium atom, determined by various methods, ranges from 0.85 to 1.33 Å. About 8.8 ml of Helium dissolves in 1 liter of water at 20°C. The primary ionization energy of Helium is greater than that of any other element - 39.38 10 -13 J (24.58 eV); Helium has no electron affinity. Liquid Helium, consisting only of 4 He, exhibits a number of unique properties.

Chemical properties of Helium. So far, attempts to obtain stable chemical compounds of helium have ended in failure.

Getting Helium. In industry, helium is obtained from helium-containing natural gases (at present, deposits containing > 0.1% Helium are mainly exploited). Helium is separated from other gases by deep cooling, using the fact that it is more difficult to liquefy than all other gases.

Helium application. Due to its inertness, helium is widely used to create a protective atmosphere during melting, cutting and welding. active metals. Helium is less electrically conductive than another inert gas - argon, and therefore an electric arc in an atmosphere of Helium gives higher temperatures, which significantly increases the speed of arc welding. Due to its low density, combined with incombustibility, helium is used to fill stratostats. Helium's high thermal conductivity, its chemical inertness, and its extremely low ability to enter into a nuclear reaction with neutrons make it possible to use Helium to cool nuclear reactors. Liquid Helium is the coldest liquid on Earth and serves as a refrigerant in various scientific studies. One of the methods for determining their absolute age is based on the determination of the helium content in radioactive minerals. Due to the fact that helium is very poorly soluble in blood, it is used as constituent part artificial air supplied for breathing to divers (replacement of nitrogen by Helium prevents the occurrence of decompression sickness). The possibilities of using helium in the atmosphere of a spacecraft cabin are also being studied.

Helium liquid. The relatively weak interaction of Helium atoms causes it to remain gaseous to lower temperatures than any other gas. The maximum temperature below which it can be liquefied (its critical temperature T k) is 5.20 K. Liquid Helium is the only non-freezing liquid: at normal pressure, Helium remains liquid at arbitrarily low temperatures and solidifies only at pressures exceeding 2 5 MN/m 2 (25 at).

Liquid

Helium goes under the second serial number in the periodic system of elements of Mendeleev. It is one of the main elements of the inert group of gases. Helium is denoted by the Latin letters "He" and has atomic number two. This gas is odorless, colorless and tasteless.
Helium gas is one of the most abundant elements in the universe and comes just behind hydrogen in quantity. Helium is also one of the lightest elements. To obtain helium, the method of fractional distillation (low-temperature separation process) is used.

Discovery of helium

During a solar eclipse in the city of Guntur in 1868, French scientist Pierre Jansen was able to study the solar chromosphere using a spectroscope. He was able to determine that the prominences of the Sun contain not only hydrogen, but also other elements. While new element taken for D sodium. But Pierre Jansen wrote a letter to the French Academy of Sciences, where he outlined his theory of the discovery of a new element.
A couple of months later, an astronomer from England, Norman Lockyer, conducted his own research and, using a spectroscope, also revealed new line in the spectrum of an unknown element with a length of 587.56 nm. During a joint work with his friend chemist Edward Frankland, Norman Lockyer gave the name of the discovered element - helium, which meant ancient Greek"Sun".
In honor of the discovery of a new element, the French Academy decided to award honorary medals to both scientists and to Norman Lockyer and Pierre Jansen.
The Italian Luigi Palmieri was able to identify helium in 1881 during his research on volcanic gases. Luigi Palmieri used calcination to heat the volcanic product in a Bunsen burner and tried to determine the full range of gases produced. But Palmieri was never able to clearly formulate his research and therefore his experiments were not given much importance. But many years later, helium and argon were indeed found in volcanic gases.
The discovery of helium on Earth occurred in 1895, when the Scottish chemist William Ramsay was studying gases obtained from the decomposition of the mineral cleveite. Using a spectrometer, he was able to detect a yellow line in the spectrum of gases, which indicated the presence of helium. For additional research, William Ramsay sent samples to scientist William Crookes. Additional studies have shown that the yellow line coincides with the spectrum earlier discovered helium in the Sun's chromosphere. Later, the Swedish chemists N. Lengle and P. Kleve were able to accurately determine the atomic weight of helium by repeating Ramsay's experiments with cleveite. The final point in the discovery of helium on Earth in 1896 was put by Siegbert Friedländer, Edward Bailey and Heinrich Kaiser, who determined the presence of helium in the atmosphere of our planet.
Later, Ramsay continued his research on helium and found that helium often accompanies thorium and uranium. In 1906, the scientists Royds and Resenford discovered that the alpha particles of these radioactive elements were helium nuclei. It was thanks to Ramsay's research that the beginning of the theory of the structure of the atom was laid.
Liquid helium was first obtained by throttling by Dutch physicist Heike Kamerling-Onnes. He cooled helium in hydrogen boiling in a vacuum. It was not possible to obtain solid helium until 1926. German physicist Willem Hendrik was able to compress helium under high pressure and separate the crystals.
In 1932, the scientist Keez investigated the dependence of the heat capacity of liquid helium and temperature. He learned that at a temperature of 2.1 K (the exact value = 2.172 K.), a smooth rise in the heat capacity of helium is replaced by a sharp drop and the heat capacity graph looks like the Greek letter "lambda" (?). In connection with this discovery, this temperature point was given the name "?-point". It is at this point that global changes occur with helium. One phase of liquid helium replaces another and no heat is released. Helium below the "?-dot" was given the designation helium-II, and above helium-I.
The phenomenon of helium superfluidity was first discovered by the Soviet scientist Pyotr Leonidovich Kapitsa, who studied the properties of liquid helium-II. He was able to prove that liquid helium-II flows with virtually no friction.
origin of name
The word helium has the ending "-y" (lat. "-um" - "Helium"), which is typical for the designation of metals in the periodic system of elements. This is due to the fact that Lockyer, when discovering helium, suggested that it was a metal and gave such a name. And it was no longer possible to rename it to “Helion” with the ending “-on”, since this name was assigned to the nucleus of the light isotope of helium (helium-III)

Finding helium

In space
In the universe, helium is the second most abundant. Most of the helium in space was formed after big bang, during the period of primary nucleosynthesis. On this moment helium is formed in the universe due to the thermonuclear fusion of hydrogen in the interior of stars. A small part of helium is formed in the earth's crust during the alpha decay of heavy elements and seeps through the earth's crust, bonding with particles of natural gas. The concentration of helium in natural gas can reach seven percent or more of the volume.

In the earth's atmosphere
Helium in the earth's atmosphere is obtained as a result of the decay of the elements Ac, Th, U. And the content of helium in the atmosphere reaches 7.24?10?5% by weight and 5.27?10?4% by volume. Helium reserves are estimated at about 5×1014 m?. Usually the concentration of helium in other gases does not exceed two percent, and in very rare cases there are gases in which the helium content reaches 8-15%.
In the earth's crust
Helium ranks second after argon in terms of content in the earth's crust. In terrestrial matter, the helium content is estimated at about 3 g/t. The highest concentration of helium is observed in minerals containing thorium, samarium, uranium, monazite, gadolinite, fergusonite, cleveite, and thorianite. At the same time, the content of helium in thorianite can reach 10.5 l/kg, in the rest of the mineral it ranges from 0.8 to 3.5 l/kg.

Helium definition
To qualitatively determine helium, an analysis of the emission spectra is used (lines 388.86 nm and 587.56 nm). Quantitatively, helium is determined by chromatographic and mass spectrometric methods. Methods are also used that are based on measuring the physical properties of helium, such as density, thermal conductivity, and so on.
Physical properties helium
Helium is an inert chemical element. It is non-toxic, colorless, tasteless and odorless. Under normal conditions, helium is a monatomic gas with a boiling point of 4.215 K (helium IV). The solid state of helium is achieved only at pressures of the order of 25 atmospheres and above. Without pressure, helium does not turn into a solid state even at temperatures close to absolute zero. Most helium compounds are unstable under normal conditions and require special conditions to form bonds.
The effect of helium on the body
For the most part, inert gases affect the body, causing drug intoxication. The impact of simple helium at normal pressure on the body has no effect. With an increase in pressure, a person may experience high blood pressure syndrome.

Properties in the gas phase
Helium behaves like an ideal gas under normal conditions. In most manifestations, helium is a polyatomic gas with a density of 0.17847 kg/m?. The thermal conductivity of helium under normal conditions is 0.1437 W / (m.K), more than that of hydrogen and other gases. The specific heat capacity under normal conditions is 5.23 kJ / (kg.K), and in hydrogen 14.23 kJ / (kg.K).
When current is passed through a tube filled with helium, discharges of various colors can be observed, which depend on the pressure in the tube. If you reduce the pressure, the colors will change from pink, yellow to green and orange. This is due to the fact that the spectrum of helium contains several lines that range from the ultraviolet to the infrared spectrum. The main lines of the helium spectrum lie between 706.52 nm and 447.14 nm. A decrease in pressure in the tube leads to an increase in the electron path length, and the energy from its collision with helium atoms increases. As a result, the excitation of atoms and higher energy occurs, which leads to a shift in the spectral lines.
Helium is slightly soluble in water compared to other gases. At a temperature of 20 °C, only 8.8 ml of helium dissolves in one liter of water. 2.5 ml dissolves in ethanol at 15°C and 3.2 ml at 25°C. The diffusion rate of helium in solid materials is several times greater than that of other gases. For example, the diffusion of helium is 65% greater than that of hydrogen.
Helium has a refractive index closer to unity than other gases. Helium at normal temperature has a negative Joule-Thomson coefficient. That is, it does not heat up when it expands freely. Helium cools during free expansion only at temperatures below 40 K (below the Joule-Thomson inversion temperature) at normal pressure. With a decrease in temperature, helium is able to go into a liquid state during expansion cooling. Such cooling is possible with the help of an expander.

Chemical properties of helium
Helium is one of the least active chemical elements among the inert gases. Most helium compounds exist in the gas phase, in the form of excimer molecules, which have an unstable ground state and a stable excited electronic state. Helium is able to form diatomic molecules (He2), compounds with fluorine (HeF) and chlorine (HeCl).

Getting helium
Helium-containing natural gas deposits are used industrially to produce helium. Deep cooling is used to separate helium from other gases. Helium liquefies better than other gases. With the help of throttling, helium is purified from carbon dioxide and hydrocarbons in several stages. The result is a mixture of several gases (helium, hydrogen and neon). Further, CuO and a temperature of 650-800 K are used to separate hydrogen from helium. Helium is finally purified by cooling the mixture in a boiling N2 vacuum and adsorbing the remaining impurities. This method produces pure helium (up to 99.8% by volume)
In Russia, helium gas is produced from petroleum or natural gas. The main Russian helium production plant is OOO Gazprom dobycha Orenburg. This plant extracts helium from gas with a low helium content, which increases its final cost. To reduce the cost of helium, projects were developed for the development of deposits in Eastern Siberia and Far East. At this stage, the main supplier of helium to the world market is the United States, which accounts for about 140 million m? helium per year. All the largest helium deposits are located in the United States. In terms of helium production, Russia ranks third after the United States and Algeria.

Helium transportation
In order to transport helium, special gas cylinders are used (GOST 949-73). These cylinders must be placed in special containers so as not to damage them on the road. For the transport of packaged helium cylinders, any transport suitable for transporting gases can be used. Liquid helium is transported in special transport containers. When transporting liquid helium, helium containers must be in a vertical position. With proper transportation, helium can be transported both by rail and by special vehicles.

Helium application
Helium is widely used in national economy and industry. In metallurgy, helium is used in the smelting of pure metals. Helium is used as an E939 food additive and packaging agent. Due to its unique properties, helium is used as a refrigerant. Helium is filled with balloons, used in medicine as a breathing mixture, used in lasers and as coolants in boilers and pipelines.

Helium

HELIUM-I; m.[from Greek. helios - the sun]. A chemical element (He), an odorless chemically inert gas, the lightest after hydrogen.

◁ Helium, th, th. G-th core.

(lat. Helium), a chemical element of group VIII of the periodic system, belongs to the noble gases; colorless and odorless, density 0.178 g/l. It is more difficult to liquefy than all known gases (at -268.93ºC); the only substance that does not solidify at normal pressure, no matter how deep it is cooled. Liquid helium is a quantum liquid that has superfluidity below 2.17ºK (-270.98ºC). A small amount of helium is found in the air and the earth's crust, where it is constantly formed during the decay of uranium and other α-radioactive elements (α-particles are the nuclei of helium atoms). Helium is much more common in the Universe, for example, on the Sun, where it was first discovered (hence the name: from the Greek hēlios - the Sun). Helium is obtained from natural gases. They are used in cryogenic technology, for creating inert media, in aeronautics (for filling stratospheric balloons, balloons, etc.).

HELIUM (lat. Helium), He (read "helium"), a chemical element with atomic number 2, atomic mass 4.002602. Belongs to the group of inert, or noble, gases (group VIIIA of the periodic system), is in the 1st period.
Natural helium consists of two stable nuclides: 3 He (0.00013% by volume) and 4 He. The almost complete predominance of helium-4 is associated with the formation of nuclei of this nuclide during the radioactive decay of uranium, thorium, radium and other atoms, which took place during the long history of the Earth.
The radius of a neutral helium atom is 0.122 nm. Electronic configuration of a neutral unexcited atom 1s 2 . The energies of successive ionization of a neutral atom are 24.587 and 54.416 eV, respectively (the helium atom has the highest energy of detachment of the first electron among neutral atoms of all elements).
The simple substance helium is a light monatomic gas without color, taste or smell.
Discovery history
The discovery of helium began in 1868, when French astronomers P. J. Jansen observed a solar eclipse. (cm. Jansen Pierre Jules Cesar) and Englishman D. N. Lockyer (cm. Lockyer Joseph Norman) independently discovered in the spectrum of the solar corona (cm. SOLAR CORONA) yellow line (it was called D 3-line), which could not be attributed to any of the elements known at that time. In 1871, Lockyer explained its origin by the presence of a new element on the Sun. In 1895, the Englishman W. Ramsay (cm. RAMZAY William) isolated a gas from the natural radioactive ore cleveite, in the spectrum of which the same D 3-line. Lockyer gave the new element a name reflecting the history of its discovery (Greek Helios, the sun). Since Lockyer believed that the discovered element was a metal, he used the ending "lim" in the Latin name of the element (corresponding to the Russian ending "ij"), which is usually used in the name of metals. Thus, helium, long before its discovery on Earth, received a name that distinguishes it from the names of other inert gases with an ending.
Being in nature
In atmospheric air, the helium content is very low and is about 5.27·10 -4% by volume. In the earth's crust it is 0.8 10 -6%, in sea water - 4 10 -10%. The source of helium is oil and helium-bearing natural gases, in which the helium content reaches 2-3%, and in rare cases 8-10% by volume. But in space, helium is the second most common element (after hydrogen): it accounts for 23% of the cosmic mass.
Receipt
The technology for producing helium is very complex: it is isolated from natural helium-bearing gases using the deep cooling method. There are deposits of such gases in Russia, the USA, Canada and South Africa. Helium is also contained in some minerals (monazite, thorianite, and others), while from 1 kg of the mineral, when heated, up to 10 liters of helium can be isolated.
Physical properties
Helium is a light non-combustible gas, the density of gaseous helium under normal conditions is 0.178 kg / m 3 (only hydrogen gas is less). The boiling point of helium (at normal pressure) is about 4.2K (or -268.93°C, which is the lowest boiling point).
At normal pressure, liquid helium cannot be turned into a solid even at temperatures close to absolute zero (0K). At a pressure of about 3.76 MPa, the melting point of helium is 2.0K. The lowest pressure at which the transition of liquid helium to a solid state is observed is 2.5 MPa (25 atm), while the melting point of helium is about 1.1 K (–272.1 °C).
0.86 ml of helium dissolves in 100 ml of water at 20 °C, and its solubility is even lower in organic solvents. Light helium molecules pass (diffuse) well through various materials (plastics, glass, some metals).
For liquid helium-4 cooled below -270.97 °C, a number of unusual effects are observed, which gives reason to consider this liquid as a special, so-called quantum liquid. This liquid is usually referred to as helium-II, in contrast to liquid helium-I, a liquid that exists at slightly higher temperatures. The graph of the heat capacity of liquid helium with temperature changes resembles the Greek letter lambda (l). The transition temperature of helium-I to helium-II is 2.186 K. This temperature is often called the l-point.
Liquid helium-II is able to quickly penetrate through the smallest holes and capillaries, without revealing viscosity (the so-called superfluidity). (cm. SUPERFLUIDITY) liquid helium-II). In addition, helium-II films quickly move over the surface solids, as a result of which the liquid quickly leaves the vessel in which it was placed. This property of helium-II is called supercreep. The superfluidity of helium-II was discovered in 1938 by the Soviet physicist P. L. Kapitsa (cm. KAPITS Pyotr Leonidovich)(Nobel Prize in Physics, 1978). The explanation for the unique properties of helium-II was given by another Soviet physicist L. D. Landau (cm. LANDAU Lev Davidovich) in 1941-1944 (Nobel Prize in Physics, 1962).
Helium does not form any chemical compounds. True, in rarefied ionized helium it is possible to detect sufficiently stable diatomic He 2 + ions.
Application
Helium is used to create an inert and protective atmosphere when welding, cutting and melting metals, when pumping rocket fuel, to fill airships and balloons, as a component of the helium laser environment. Liquid helium, the coldest liquid on Earth, is a unique refrigerant in experimental physics that allows ultra-low temperatures to be used in scientific research(for example, when studying electrical superconductivity (cm. SUPERCONDUCTIVITY)). Due to the fact that helium is very poorly soluble in blood, it is used as an integral part of the artificial air supplied to divers for breathing. Replacing nitrogen with helium prevents decompression sickness (cm. caisson disease)(when ordinary air is inhaled, nitrogen under high pressure dissolves in the blood, and then is released from it in the form of bubbles that clog small vessels).

encyclopedic Dictionary. 2009 .

See what "Helium" is in other dictionaries:

- (lat. Helium) He, a chemical element of group VIII of the periodic system, atomic number 2, atomic mass 4.002602, belongs to the noble gases; colorless and odorless, density 0.178 g/l. It is more difficult to liquefy than all known gases (at 268.93 ° C); ... ... Big Encyclopedic Dictionary

- (Greek, from helyos sun). An elementary body discovered in the solar spectrum and present on earth in some rare minerals; is present in the air in trace amounts. Dictionary of foreign words included in the Russian language. Chudinov A.N ... Dictionary of foreign words of the Russian language

- (symbol He), a gaseous non-metallic element, NOBLE GAS, discovered in 1868. First obtained from the mineral clevit (a variety of uranite) in 1895. Currently, its main source is natural gas. Also contained in... Scientific and technical encyclopedic dictionary

Me, husband. , old Eliy, I. Father: Gelievich, Gelievna. Derivatives: Gelya (Gela); Elya. Origin: (From the Greek. hēlios sun.) Name day: July 27 Dictionary of personal names. Helium See Ellius. Day Angel. Reference … Dictionary of personal names

HELIUM- chem. element, symbol He (lat. Helium), at. n. 2, at. m. 4.002, refers to inert (noble) gases; colorless and odorless, density 0.178 kg/m3. Under normal conditions, hydrogen is a monatomic gas, the atom of which consists of a nucleus and two electrons; formed... Great Polytechnic Encyclopedia

- (Helium), He, a chemical element of group VIII of the periodic system, atomic number 2, atomic mass 4.002602; refers to the noble gases; the lowest boiling substance (tbp 268.93shC), the only one that does not solidify at normal pressure; ... ... Modern Encyclopedia

Chem. eighth element. periodic system, serial number 2; inert gas with at. V. 4.003. Consists of two stable isotopes He4 and He3. Soder. their changeable and depends on the source of formation, but the heavy isotope always prevails. IN… … Geological Encyclopedia

Helium- (Helium), He, a chemical element of group VIII of the periodic system, atomic number 2, atomic mass 4.002602; refers to the noble gases; the lowest boiling substance (tbp 268.93 ° C), the only one that does not solidify at normal pressure; ... ... Illustrated Encyclopedic Dictionary

Sunny Dictionary of Russian synonyms. helium n., number of synonyms: 4 gas (55) name (1104) … Synonym dictionary

HELIUM, me, husband. A chemical element, an inert, colorless and odorless gas, the lightest gas after hydrogen. | adj. helium, oh, oh. Dictionary Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

- (Helium) colorless and odorless gas, chemically inactive, 7.2 times lighter than air, does not burn. In a very small amount is in the atmosphere (1/2000%). Due to its lightness and incombustibility, it is mainly used to fill airships ... Marine Dictionary

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• The White Horse, Helium Ryabov, 384 pages state border, films One of us, Theft, Favorite, etc. His pen belongs to the book The Tale of ... Category:

Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the group of noble gases in the periodic table. Its boiling point is the lowest among all elements. After hydrogen, helium is the second lightest and second most abundant element in the observable universe, present at about 24% of the total mass of elements, more than 12 times the mass of all heavier elements combined. Its abundance is due to the very high nuclear binding energy (per nucleon) of helium-4 relative to the next three elements after helium. This helium-4 binding energy also explains why helium is a product of both nuclear fusion and radioactive decay. Most of the helium in the universe is in the form of helium-4, and is believed to have formed during the Big Bang. A large amount of new helium is created by the nuclear fusion of hydrogen in stars. Helium is named after the Greek sun god, Helios. Helium was first discovered as an unknown yellow spectral line signature in sunshine during a solar eclipse in 1868 by Georges Rayet, Captain C.T. Haig, Norman R. Pogson, and Lieutenant John Herschel.

This observation was subsequently confirmed by the French astronomer Jules Janssen. Janssen is often credited with discovering this element along with Norman Lockyer. Janssen recorded the spectral line of helium during the 1868 solar eclipse, while Lockyer observed the phenomenon from Britain. Lockyer was the first to suggest that this line was associated with a new element, to which he named helium. The formal discovery of the element was made in 1895 by two Swedish chemists, Per Theodor Cleve and Nils Abraham Langlet, who discovered helium coming from uranium ore cleveite. In 1903, large reserves of helium were discovered in natural gas fields in parts of the United States. To date, the United States is the largest supplier of gas. Liquid helium is used in cryogenics (its largest single use, absorbing about a quarter of production), in particular in the cooling of superconducting magnets, with the main commercial application being in MRI scanners. Other industrial uses for helium are as a pressurizing and purge gas, as a shielding atmosphere for arc welding, and in processes such as growing crystals to make silicon wafers. A well-known but minor use of helium is as a lifting gas for balloons and airships. As with any gas whose density differs from that of air, inhaling a small amount of helium temporarily changes the timbre and quality of the human voice. In scientific research, the behavior of the two liquid phases of helium-4 (helium I and helium II) is important for researchers studying quantum mechanics (in particular, the property of superfluidity) and for scientists studying phenomena such as superconductivity in matter near absolute zero. On Earth, helium is relatively rare - 5.2 ppm. by volume in the atmosphere. Today, most of the helium present on Earth is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium, although there are other examples), since the alpha particles emitted by such decays are composed of helium-4 nuclei. This radiogenic helium is captured in natural gas at concentrations up to 7% by volume, from which it is recovered commercially by a low-temperature separation called fractional distillation. Previously, terrestrial helium was a non-renewable resource because, once released into the atmosphere, it could easily travel into space, and the element was thought to be increasingly scarce. However, recent studies show that helium produced on Earth from radioactive decay may be collected in natural gas reserves in larger quantities than expected, in some cases released by volcanic activity.

Story

Scientific discoveries

The first evidence of the existence of helium was made on August 18, 1868. A bright yellow line with a wavelength of 587.49 nanometers was observed in the spectrum of the Sun's chromosphere. This line was discovered by French astronomer Jules Janssen during a total solar eclipse in Guntur, India. This line was originally thought to be sodium. On October 20 of the same year, English astronomer Norman Lockyer observed a yellow line in the Sun's spectrum, which he called the D3 Fraunhofer line because it was close to the known sodium D1 and D2 lines. The scientist came to the conclusion that this line was caused by an element of the Sun, unknown on Earth. Lockyer and the English chemist Edward Frankland named the element by the Greek word for the sun, ἥλιος (helios). In 1881, Italian physicist Luigi Palmieri first detected helium on Earth through its D3 spectral line, while analyzing material that was sublimated during the eruption of Mount Vesuvius. On March 26, 1895, Scottish chemist Sir William Ramsay isolated helium on Earth by treating the mineral cleaveite (a range of uraninites with at least 10% rare earth elements) with mineral acids. Ramsey was looking for argon, but after separating nitrogen and oxygen from the gas given off by sulfuric acid, he noticed a bright yellow line that matched the D3 line seen in the Sun's spectrum. These samples were identified as helium by Lockyer and the British physicist William Crookes. Helium was independently isolated from kleveite in the same year by chemists Per Theodor Kleve and Abraham Langlet in Uppsala, Sweden, who collected enough gas to accurately determine its atomic weight. Helium was also isolated by the American geochemist William Francis Hillebrand prior to Ramsey's discovery, when he noticed unusual spectral lines while testing a sample of the mineral uraninite. Hillebrand, however, attributed these lines to nitrogen. In 1907, Ernest Rutherford and Thomas Royds demonstrated that alpha particles were helium nuclei by allowing the particles to penetrate the thin glass wall of an evacuated tube and then creating a discharge in the tube to study the spectra of the new gas inside. In 1908, helium was first liquefied by the Dutch physicist Heike Kamerlingh Onnes by cooling the gas to less than one kelvin. He tried to solidify the gas by lowering the temperature even further, but failed because helium does not solidify when atmospheric pressure. Onnes' student, Willem Hendrik Keesom, was eventually able to solidify 1 cm3 of helium in 1926 by adding additional external pressure. In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 had virtually no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. This phenomenon is associated with Bose-Einstein condensation. In 1972, the same phenomenon was observed for helium-3, but at temperatures much closer to absolute zero, by American physicists Douglas D. Osheroff, David M. Lee, and Robert C. Richardson. The phenomenon in helium-3 is believed to be due to the pairing of helium-3 fermions to form bosons, similar to the Cooper pairs of electrons that produce superconductivity.

Extraction and use

After an oil drilling operation in 1903 in Dexter, Kansas, a gas geyser was produced that did not burn, and Kansas state geologist, Erasmus Haworth, collected samples of the escaping gas and took them to the University of Kansas at Lawrence, where, with the help of chemists Hamilton Cudi and David McFarland, he found that the gas consisted of 72% nitrogen, 15% methane (a combustible percentage with only enough oxygen), 1% hydrogen, and 12% an unidentifiable gas. Upon further analysis, Cady and McFarland found that 1.84% of the gas sample was helium. This showed that, despite its general rarity on Earth, helium was concentrated in large quantities beneath the American Great Plains, available for extraction as a by-product of natural gas. This allowed the United States to become the world's leading supplier of helium. Following the suggestion of Sir Richard Threlfall, Navy The United States sponsored three small experimental helium plants during World War I. The goal was to supply boom balloons with a non-flammable gas lighter than air. During this program, 5,700 m3 (200,000 cu ft) of 92% helium was produced, although less than one cubic meter of this gas had previously been produced. Some of this gas was used in the world's first helium airship, a US Navy C-7, which made its maiden voyage from Hampton Roads, Virginia to Bolling Field in Washington, D.C. on December 1, 1921, almost two years before construction. the first helium-filled rigid airship in September 1923 at the Shenandoah factory. Although the extraction process using low-temperature gas liquefaction was not developed at that time, during the First World War, production continued. Helium was mainly used as a lifting gas in aircraft lighter than air. During World War II, the demand for helium as a lifting gas and for shielded arc welding increased. The helium mass spectrometer was also of great importance in the Manhattan Project (the code name for the US work on the first atomic bomb during World War II). The United States government established the National Helium Reserve in 1925 at Amarillo, Texas, for the purpose of supplying military airships in times of war and commercial airships in times of peace. Because of the Helium Control Act (1927), which banned the export of rare helium, which was then a US monopoly, along with the prohibitive cost of gas, the Hindenburg, like all German Zeppelins, was forced to use hydrogen as a lifting gas. The helium market was suppressed after World War II, but stocks were expanded in the 1950s to supply liquid helium as a refrigerant for oxyhydrogen rocket fuel (among other uses) during the "space race" and cold war . The use of helium in the United States in 1965 was more than eight times the peak wartime consumption. Since the "Helium Acts Amendments of 1960" (Public Law 86-777), the United States Bureau of America has set up five private plants to recover helium from natural gas. For this helium conservation program, the Bureau built a 425-mile (684-kilometer) pipeline from Bushton, Kansas to connect these plants to the government's partially depleted Cliffside gas field near Amarillo, Texas. This helium-nitrogen mixture was injected and stored in the Cliffside gas field until needed, during which time it was further refined. By 1995, a billion cubic meters of gas had been collected and the reserve was $1.4 billion in debt, prompting the United States Congress to liquidate the reserve in 1996. The "Helium Privatization Act of 1996" (Public Law 104-273) forces the United States Department of the Interior to release the reserve and begin sales from 2005. Helium produced between 1930 and 1945 was approximately 98.3% pure (2% nitrogen), which was sufficient for airships. In 1945, a small amount of 99.9% helium was obtained for welding. By 1949, 99.95% commercial grade A helium was available. For years, the United States produced more than 90% of the world's commercially used helium, with mining facilities in Canada, Poland, Russia and other countries producing the rest. In the mid-1990s, a new plant in Argeve, Algiers, began operating, producing 17 million cubic meters (600 million cubic feet of helium), with enough production to cover all of Europe's needs. Meanwhile, by 2000, US helium consumption had increased to over 15 million kg per year. In 2004-2006, additional plants were built in Ras Laffan, Qatar and Skikda, Algeria. Algeria quickly became the second leading producer of helium. During this time, both helium consumption and helium production costs increased. From 2002 to 2007 helium prices have doubled. As of 2012, the United States National Helium Reserve accounted for 30 percent of the world's helium reserves. The reserve is expected to run out in 2018. Regardless, a proposed bill in the United States Senate would allow the reserve to continue selling gas. Other large reserves of helium were in the Hugoton state of Kansas, USA, and nearby gas fields in Kansas, as well as in the Texas and Oklahoma highs. New helium plants were due to open in 2012 in Qatar, in Russia and in Wyoming in the US, but they were not expected to reduce the shortage. In 2013, construction began on the world's largest helium plant in Qatar. 2014 was widely recognized as the year of oversupply in the helium business, after years of shortages.

Characteristics

helium atom

Helium in quantum mechanics

From a quantum mechanics perspective, helium is the second simplest atom to model, following the hydrogen atom. Helium has two electrons per atomic orbitals, surrounding a nucleus containing two protons and (usually) two neutrons. As in Newtonian mechanics, no system of more than two particles can be solved with an exact analytical mathematical approach, and helium is no exception. Thus, numerical mathematical methods are required, even to solve a system consisting of one nucleus and two electrons. Such computational chemistry methods have been used to generate a quantum mechanical picture of helium electron binding that is less than 2% accurate over several computational steps. Such models show that each electron in helium partially shields one nucleus from another, so that the effective nuclear charge Z that each electron sees is about 1.69 units, and not 2 charges of the classical "bare" helium nucleus.

Relative stability of the helium-4 nucleus and electron shell

The nucleus of the helium-4 atom is identical to the alpha particle. High-energy electron scattering experiments show that its charge decreases exponentially from a maximum at the central point, just like the charge density of helium's own electron cloud. This symmetry reflects a similar underlying physics: a pair of neutrons and a pair of protons in a helium nucleus obey the same quantum mechanical rules as a pair of helium electrons (although the nuclear particles are subject to a different nuclear binding potential), so that all of these fermions completely occupy the 1s orbitals in the pairs , and neither of them has an orbital momentum, and each of them cancels the own spin of the other. Adding any other of these particles would require angular momentum and release substantially less energy (in fact, no five-nucleon nucleus is stable). Thus, this scheme is energetically extremely stable for all these particles, and this stability explains many important facts about helium in nature. For example, the stability and low energy of the electron cloud state in helium explains the chemical inertness of the element, as well as the lack of interaction of helium atoms with each other, creating the lowest melting and boiling points of all elements. Likewise, the special energy stability of the helium-4 core, created by similar effects, explains the ease of producing helium-4 in atomic reactions that involve either the release of heavy metals or their fusion. Some stable helium-3 (2 protons and 1 neutron) is produced in hydrogen fusion reactions, but this amount is very small compared to the highly sensitive energy of helium-4. The unusual stability of the helium-4 nucleus is also important cosmologically: it explains the fact that in the first few minutes after the Big Bang, during the creation of a "mess of free protons and neutrons", which were originally created in a ratio of approximately 6: 1, cooled to such extent that nuclear binding became possible, almost all of the first formed composite atomic nuclei were helium-4 nuclei. helium-4 binding was so tight that helium-4 production consumed almost all of the free neutrons in a few minutes before they could be beta decayed, and also left a small amount to form heavier atoms such as lithium, beryllium or boron . The nuclear binding of helium-4 per nucleon is stronger than any of these elements, and thus, when helium was formed, there was no energetic drive to create elements 3, 4, and 5. It was not energetically advantageous for helium to fuse into the next element with less energy per nucleon, carbon. However, due to the lack of intermediate elements, this process requires three helium nuclei hitting each other almost simultaneously. Thus, within minutes of the Big Bang, there was no time for a significant amount of carbon to form before the early expanding universe cooled to a temperature and pressure where helium-carbon fusion would have been impossible. Because of this, the early universe had a hydrogen/helium ratio similar to today's (3 parts hydrogen to 1 part helium-4 by mass), with nearly all neutrons in the universe captured by helium-4. All of the heavier elements (including those needed for rocky planets like Earth and for carbon or other life forms) were thus created after the Big Bang in stars that were hot enough to fuse helium itself. All elements, except hydrogen and helium, today make up only 2% of the mass of atomic matter in the universe. Helium-4, by contrast, makes up about 23% of the ordinary matter in the universe—nearly all of the ordinary matter that isn't hydrogen.

Gas and plasma phases

Helium is the second least reactive noble gas after neon and therefore the second least reactive of all elements. It is inert and monoatomic under all standard conditions. Due to the relatively low molar (atomic) mass of helium, its thermal conductivity, specific heat capacity, and speed of sound in the gas phase are greater than those of any other gas other than hydrogen. For these reasons, and because of the small size of monatomic helium molecules, helium diffuses through solid particles at three times the speed of air and about 65% of that of hydrogen. Helium is the least water-soluble monatomic gas and one of the less water-soluble gases (CF4, SF6 and C4F8 have lower mole fraction solubility: 0.3802, 0.4394 and 0.2372 x2/10-5 respectively against 0.70797 x2/10- 5 for helium), in addition, the refractive index of helium is closer to unity than the refractive index of any other gas. Helium has a negative Joule-Thomson coefficient at normal temperature environment, which means that it heats up when it is allowed to expand freely. Just below its Joule-Thomson inversion temperature (about 32 to 50 K at 1 atmosphere), helium cools as it expands freely. After supercooling below this temperature, helium can be liquefied by refrigeration. Most extraterrestrial helium is in a plasma state and has properties quite different from those of atomic helium. In a plasma, helium's electrons are not bound to its nucleus, resulting in very high electrical conductivity even when the gas is only partially ionized. Charged particles are strongly affected by magnetic and electric fields. For example, in the solar wind, along with ionized hydrogen, particles interact with the Earth's magnetosphere, resulting in Birkeland currents and aurora.

liquid helium

Unlike any other element, helium will remain liquid down to absolute zero at normal pressures. This is a direct influence of quantum mechanics: in particular, the zero-point energy of the system is too high to allow freezing. Solid helium requires a temperature of 1-1.5 K (about -272 °C or -457 °F) at a pressure of about 25 bar (2.5 MPa). It is often difficult to tell solid helium from liquid helium because the refractive index of the two phases is almost the same. The solid has a distinct melting point and has a crystalline structure, but it is highly compressible; applying pressure in the laboratory can reduce its volume by more than 30%. With a volume modulus of about 27 MPa, helium is 100 times more compressible than water. Solid helium has a density of 0.214±0.006 g/cm3 at 1.15 K and 66 atm; the predicted density at 0 K and 25 bar (2.5 MPa) is 0.187 ± 0.009 g/cm3. At higher temperatures, helium will solidify with sufficient pressure. At room temperature, this requires about 114,000 atm.

Helium state I

Below its boiling point of 4.22 kelvin and above its lambda point of 2.1768 kelvin, the isotopic helium-4 exists in its normal colorless liquid state called helium I. Like other cryogenic liquids, helium I boils when it is heated and contracts when its temperature drops. However, below the lambda point, helium does not boil, and it expands as the temperature drops further. Helium I has a gaseous refractive index of 1.026, which makes it so difficult to see its surface that pop-up polystyrene foams are often used to observe its surface. This colorless liquid has a very low viscosity and a density of 0.145-0.125 g/ml (about 0-4 K), which is only one-fourth of the value expected from classical physics. To explain this property, quantum mechanics, and therefore both states of liquid helium (helium I and helium II) are called quantum liquids, meaning that they exhibit atomic properties on a macroscopic scale. This may be due to the fact that the boiling point of helium is so close to absolute zero that it prevents random molecular motion (thermal energy) from masking its atomic properties.

Helium II state

Liquid helium below its lambda point (called helium II) has very unusual characteristics. Due to its high thermal conductivity, when it boils, it does not bubble but evaporates directly from the surface. Helium-3 also has a superfluid phase, but only at much lower temperatures; as a result, little is known about the properties of this isotope. Helium II is a superfluid liquid and a quantum mechanical state with strange properties. For example, when it flows through capillaries 10-7 to 10-8 m thick, it has no measurable viscosity. However, when measurements were made between two moving disks, a viscosity comparable to that of gaseous helium was observed. The present theory explains this with a two-fluid model for helium II. In this model, liquid helium below the lambda point is considered to be a substance containing a portion of ground state helium atoms that are superfluid and flow with zero viscosity, and a portion of excited helium atoms that behave like a normal liquid. In the spouting effect, a chamber is built which is connected to the helium reservoir II by a sintered disc through which superfluid helium easily flows, but through which non-superfluid helium cannot pass. If the inside of the container is heated, the superfluid helium changes to non-superfluid helium. In order to maintain an equilibrium proportion of superfluid helium, the superfluid helium flows and increases the pressure, causing liquid to be released from the container. The thermal conductivity of helium II is greater than that of any other known substance, a million times greater than that of helium I and several hundred times greater than that of copper. This is due to the fact that thermal conductivity occurs due to an exceptional quantum mechanism. Most materials that conduct heat have a valence band of free electrons that serve to transfer heat. Helium II does not have such a valence band, but nevertheless conducts heat well. The heat flux is determined by equations that are similar to the wave equation used to characterize the propagation of sound in air. When exposed to heat, it travels at 20 meters per second at 1.8 K through helium II as waves in a phenomenon known as second sound. Helium II also has a "creeping" effect. When the surface passes through the helium II level, helium II moves across the surface, against gravity. Helium II will exit the unsealed vessel, sliding down the sides until it reaches a warmer area where it evaporates. It moves in a 30 nm thick film regardless of the surface material. This film is called Rollin film after the scientist who first characterized this quality, Bernard W. Rollin. As a result of this "creeping" behavior and the ability of Helium II to flow rapidly through tiny holes, it is very difficult to contain liquid helium. If the container is not carefully constructed, helium II will crawl over the surface and through the valves until it reaches a warmer area, from where it will evaporate. Waves propagating through a Rollin film are governed by the same equation as gravitational waves in shallow water, but instead of gravity, the restoring force is the van der Waals force. These waves are known as the third sound.

isotopes

There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. In the Earth's atmosphere, there is one 3He atom per million 4He atoms. Unlike most elements, the isotopic abundance of helium varies greatly in origin due to different formation processes. The most abundant isotope, helium-4, is produced on Earth by the alpha decay of heavier radioactive elements; the resulting alpha particles are fully ionized helium-4 nuclei. Helium-4 is an unusually stable nucleus because its nucleons are arranged in full shells. It has also been formed in vast quantities in big bang nucleosynthesis. Helium-3 is present on Earth only in trace amounts; most helium-3 has been present since the formation of the earth, although some finds its way to earth trapped in cosmic dust. Trace amounts of helium are also produced in the beta decay of tritium. The rocks of the earth's crust have isotopic ratios varying by a factor of ten, and these ratios can be used to study the origin of rocks and the composition of the Earth's mantle. 3He is much more common in stars as a product of nuclear fusion. Thus, the ratio of 3He to 4He in the interstellar medium is approximately 100 times higher than on Earth. Extraplanetary material such as lunar and asteroidal regolith has trace amounts of helium-3 from being bombarded by solar winds. The lunar surface contains helium-3 at concentrations on the order of 10 ppm, much higher than the approximately 5 ppm found in earth's atmosphere. A number of scientists, beginning with Gerald Kulcinski in 1986, have proposed exploring the moon, collecting lunar regolith, and using helium-3 for fusion. Liquid helium-4 can be cooled to about 1 kelvin using evaporative cooling in a pot, which reaches 1 K. Similar cooling of lower boiling helium-3 can reach about 0.2 kelvin in a helium-3 refrigerator. Equal mixtures of liquid 3He and 4He with temperatures below 0.8 K separate into two immiscible phases due to their dissimilarity (they have different quantum statistics: helium-4 atoms are bosons, while helium-3 atoms are fermions). In refrigeration machines operating on a mixture of cryogenic substances, this immiscibility is used to achieve temperatures of several millikelvins. It is possible to produce exotic helium isotopes that quickly decay into other substances. The shortest-lived heavy isotope of helium is helium-5, with a half-life of 7.6×10-22 s. Helium-6 decays by emitting a beta particle and has a half-life of 0.8 seconds. Helium-7 also emits a beta particle as well as a gamma ray. Helium-7 and helium-8 are produced in some nuclear reactions. Helium-6 and helium-8 are known to have a nuclear halo.

Helium compounds

Helium has a valence of 0 and is chemically inactive under all normal conditions. Helium is an electrical insulator unless it is ionized. Like other noble gases, helium has metastable energy levels that allow it to remain ionized in an electrical discharge below its ionization potential. Helium can form unstable compounds known as excimers with tungsten, iodine, fluorine, sulfur, and phosphorus when it is subjected to glow discharge, electron bombardment, or reduced to plasma by other means. Thus, molecular compounds HeNe, HgHe10 and WHe2 and molecular ions He +2, He2 +2, HeH + and HeD + were created. HeH+ is also stable in its ground state, but is extremely reactive - it is the strongest Bronsted acid, and therefore can only exist in isolation, as it will protonate any molecule or prothianion it comes into contact with. This method also produced the neutral He2 molecule, which has a large number of band systems, and HgHe, which appears to be held together only by polarization forces. Helium van der Waals compounds can also form with cryogenic helium gas and atoms of some other substance such as LiHe and He2. Theoretically, there may be other true compounds, such as helium fluorohydride (HHeF), which would be similar to the HArF discovered in 2000. Calculations show that two new compounds containing a helium-oxygen bond can be stable. The two new molecular species predicted using the theory, CsFHeO and N(CH3)4FHeO, are derivatives of the metastable FHeO anion first proposed in 2005 by a group in Taiwan. If confirmed by experiment, the only remaining element with no known stable compounds would be neon. Helium atoms were inserted into the molecules of hollow carbon frameworks (fullerenes) by heating under high pressure. The created endohedral fullerene molecules are stable at high temperatures. When chemical derivatives of these fullerenes are formed, helium remains inside. If helium-3 is used, it can be easily observed using nuclear spectroscopy. magnetic resonance helium. Many fullerenes containing helium-3 have been reported. Although helium atoms are not bound by covalent or ionic bonds, these substances have certain properties and a certain composition, like all stoichiometric chemical compounds. At high pressures, helium can form compounds with various other elements. Helium nitrogen clathrate crystals (He(N2)11) were grown at room temperature at pressures of approx. 10 GPa in a high pressure chamber with diamond anvils. It was shown that the Na2He insulating electrolyte is thermodynamically stable at pressures above 113 GPa. It has a fluorite structure.

Origin and production

natural abundance

Although rare on Earth, helium is the second most abundant element in the known universe (after hydrogen), making up 23% of its baryon mass. The vast majority of helium was formed by Big Bang nucleosynthesis one to three minutes after the Big Bang. Thus, measurements of its abundance contribute to cosmological models. In stars, helium is formed by the nuclear fusion of hydrogen into proton-proton chain reactions and the CNO cycle, part of stellar nucleosynthesis. In the Earth's atmosphere, the concentration of helium by volume is only 5.2 parts per million. The concentration is low and fairly constant, despite the continuous production of new helium, because most of the helium in the Earth's atmosphere enters space through several processes. In the terrestrial heterosphere, parts of the upper atmosphere, helium and other lighter gases are the most abundant elements. Most of the helium on Earth is the result of radioactive decay. Helium is found in large quantities in uranium and thorium minerals, including cleveite, tar, carnotite, and monazite, as they release alpha particles (helium nuclei, He2+) to which electrons immediately bind once the particle is stopped by the stone. Thus, about 3,000 metric tons of helium are generated in the entire lithosphere. In the earth's crust, the concentration of helium is 8 parts per billion. In sea water, the concentration is only 4 parts per trillion. Not large quantities helium is also present in mineral springs, volcanic gas, and meteoric iron. Since helium is trapped in the earth's interior under conditions that also trap natural gas, the largest natural concentrations of helium on the planet are found in natural gas, from which most commercial helium is extracted. Helium concentrations vary widely, from a few ppm to over 7% in a small gas field in San Juan County, New Mexico. As of 2011, the world's helium reserves were estimated at 40 billion cubic meters, with a quarter of these reserves located in the South Pars / North Dome Gas-Condensate field, jointly owned by Qatar and Iran. In 2015 and 2016 more probable reserves were announced in the Rocky Mountains of North America and East Africa.

Modern mining and distribution

For large scale use, helium is extracted by fractional distillation from natural gas, which can contain up to 7% helium. Since helium has a lower boiling point than any other element, low temperature and high pressure are used to liquefy almost all other gases (mainly nitrogen and methane). The resulting crude helium gas is purified by successive temperature-lowering treatments, at which almost all of the remaining nitrogen and other gases are precipitated from the gas mixture. Activated carbon is used as the final purification step, typically producing 99.995% pure Class A helium. The main impurity in class A helium is neon. At the final stage of production, most of the helium produced is liquefied through a cryogenic process. This is essential for applications requiring liquid helium and also allows helium suppliers to reduce the cost of transporting helium over long distances, as the largest liquid helium containers have more than five times the capacity of the largest gas helium trailers. In 2008, approximately 169 million standard cubic meters of helium were recovered from natural gas or helium reserves, approximately 78% from the United States, 10% from Algeria, and most of the rest from Russia, Poland and Qatar. By 2013, an increase in helium production in Qatar (by RasGas under Air Liquide) increased Qatar's share of world helium production to 25% and made the country the second largest exporter of helium after the United States. An estimated 54 billion cubic feet (1.5 × 109 m3) of helium were discovered in Tanzania in 2016. In the United States, most helium is extracted from natural gas at Hugoton and nearby gas fields in Kansas, Oklahoma, and the Panhandle field in Texas. Most of this gas was once pipelined to the National Helium Reserve, but this reserve has been depleted and sold off since 2005 and is expected to be largely depleted by 2021, in accordance with the Responsible Helium and Stewardship Act. adopted in October 2013 (HR 527). Diffusion of raw natural gas through special semi-permeable membranes and other barriers is another way to recover and purify helium. In 1996, helium reserves were discovered in the US in such gas well complexes, about 147 billion standard cubic feet (4.2 billion SCM). At the rate of use at the time (72 million SCM per year in the US), helium would have been sufficient for about 58 years of use in the US, and less than that (perhaps 80% of the time) in the world, but the factors affecting the savings and processing affect effective reserve ratios. Helium must be extracted from natural gas because it is only a fraction of neon present in the air, but the demand for it is much higher. It is estimated that if all neon products were converted to store helium, 0.1% of the world's helium needs would be met. Similarly, only 1% of the world's helium needs could be met by reinstalling all air distillation plants. Helium can be synthesized by bombarding lithium or boron with high speed protons or by bombarding lithium with deuterons, but these processes are completely uneconomical. Helium is commercially available in either liquid or gaseous form. As a liquid, it can be supplied in small insulated containers called dewars, which hold up to 1,000 liters of helium, or large ISO containers, which have a nominal capacity of up to 42 m3 (about 11,000 US gal). In gaseous form, small quantities of helium are sold in high pressure cylinders holding up to 8 m3 (about 282 standard cubic feet) of helium, while large quantities of high pressure gas are delivered in tubular trailers with a capacity of 4,860 m3 (about 172,000 standard cubic feet). cubic feet).

Helium safety protection

According to helium preservation advocates such as physicist laureate Nobel Prize Robert Coleman Richardson writing in 2010 that the free market price of helium contributed to its "wasteful" use (for example, for helium balloons). In the 2000s, prices were lowered by the decision of the US Congress to sell large stocks of helium in the country by 2015. The price should be multiplied by 20 to eliminate excessive helium depletion, Richardson said. In his book The Future of Helium as natural resource(Routledge, 2012) Nuttall, Clarke & Glowacki (2012) also proposed the creation of an International Helium Agency (IHA) to create a sustainable market for this precious commodity.

Areas of use

While balloons are perhaps the most well-known use of helium, they represent a minor part of all helium use. Helium is used for many purposes that require some of its unique properties such as low boiling point, low density, low solubility, high thermal conductivity or inertness. Of the total world helium production in 2014, about 32 million kg (180 million standard cubic meters) of helium per year, greatest use(about 32% of the total in 2014) is in cryogenic applications, most of which are related to the cooling of superconducting magnets in medical MRI scanners and NMR spectrometers. Other main applications were pressurization and purging systems, welding, controlled atmosphere maintenance and leak detection. Other uses by category were relatively small fractions.

Controlled Atmospheres

Helium is used as a shielding gas in growing silicon and germanium crystals, in the production of titanium and zirconium, and in gas chromatography because it is inert. Due to its inertness, thermal and calorically perfect nature, high speed of sound, and high heat capacity ratio, it is also useful in supersonic wind tunnels and impulse applications.

Gas tungsten arc welding

Helium is used as a shielding gas in arc welding processes on materials that are contaminated and weakened by air or nitrogen at welding temperatures. Gas tungsten arc welding uses a range of inert shield gases, but uses helium instead of cheap argon, especially for higher thermal conductivity welding consumables such as aluminum or copper.

Less common uses

Industrial leak detection

One of the industrial applications of helium is leak detection. As helium diffuses through solids three times faster than air, it is used as a tracer gas to detect leaks in high vacuum equipment (such as cryogenic tanks) and high pressure containers. The test substance is placed in the chamber, which is then evacuated and filled with helium. Helium that passes through a leak is detected by a sensitive device (helium mass spectrometer) even at leak rates of 10-9 mbar l/s (10-10 Pa m3/s). The measurement procedure is usually carried out automatically and is called the integral helium test. A simple procedure is to fill the test object with helium and manually search for the leak using a handheld device. Helium percolation through cracks should not be confused with gas permeation through bulk material. While helium has documented permeation constants (thus a calculated penetration rate) through glasses, ceramics, and synthetics, inert gases such as helium will not penetrate most large metals.

Flying

Since helium is lighter than air, airships and hot air balloons are pumped with this gas to rise into the air. While hydrogen gas is more flotation and permeates through the membrane at a slower rate, helium has the advantage of being non-flammable and truly flame retardant. Another minor use of helium is in rockets, where helium is used as an air cushion to replace fuel and oxidizers in storage tanks and to condense hydrogen and oxygen to make rocket fuel. It is also used to clean fuel and oxidizer from ground support equipment prior to launch and to pre-cool liquid hydrogen at spacecraft. For example, the Saturn V rocket used in the Apollo program required about 370,000 m3 (13 million cubic feet) of helium to launch.

Minor commercial and recreational uses

Helium as a breathing gas does not have any narcotic properties, so helium mixtures such as trimix, heliox, and heliair are used for deep diving to reduce the effects of narcosis, which worsen with depth. As pressure increases at depth, the density of the breathing gas also increases, and the low molecular weight of helium greatly reduces the effort of breathing, reducing the density of the mixture. This reduces the number of Reynolds flows, resulting in less turbulent flow and more laminar flow, requiring less work to breathe. At depths below 150 meters (490 ft), divers breathing helium-oxygen mixtures begin to experience tremors and reduced psychomotor function, a nervous syndrome caused by increased pressure. To some extent, the addition of some narcotic gases, such as hydrogen or nitrogen, to the helium-oxygen mixture can contribute to this effect. Helium-neon lasers, a type of low-power red-beam gas laser, had various practical applications, including barcode readers and laser pointers, before they were almost universally replaced by cheaper diode lasers. Due to its inertness and high thermal conductivity, neutron transparency and the absence of radioactive isotope formation under reactor conditions, helium is used as a coolant in some nuclear reactors with gas cooling. Helium mixed with more heavy gas, such as xenon, is useful for thermoacoustic cooling due to the resulting high heat capacity and low Prandtl number. Helium persistence has environmental benefits over traditional refrigeration systems that contribute to ozone depletion or global warming. Helium is also used in some hard drives.

Scientific applications

The use of helium reduces the distorting effects of temperature changes in the space between lenses in some telescopes due to its extremely low refractive index. This method is especially used in solar telescopes where a vacuum insulated telescope tube would be too heavy. Helium is a widely used carrier gas for gas chromatography. The age of rocks and minerals containing uranium and thorium can be estimated by measuring helium levels in a process known as helium dating. Helium at low temperatures is used in cryogenics and in some applications of cryogenics. As examples of such applications, liquid helium is used to cool certain metals to the extremely low temperatures required for superconductivity, such as in superconducting magnets for magnetic resonance imaging. The Large Hadron Collider at CERN uses 96 metric tons of liquid helium to maintain a temperature of 1.9 Kelvin.

Inhalation and safety

effects

Neutral helium is non-toxic under standard conditions, does not play any biological role, and is found in trace amounts in human blood. The speed of sound in helium is almost three times the speed of sound in air. Because the fundamental frequency of the gas-filled cavity is proportional to the speed of sound in the gas, when helium is inhaled, there is a corresponding increase in the resonant frequencies of the vocal tract. The fundamental frequency (sometimes called tone) does not change, as it does by direct vibration of the vocal folds, which does not change. However, higher resonant frequencies cause a change in timbre, resulting in a thin, duck-like sound. The opposite effect, lowering resonant frequencies, can be obtained by inhaling a dense gas such as sulfur hexafluoride or xenon.

dangers

Breathing in excess helium can be dangerous because helium is a simple asphyxiant that displaces the oxygen needed for normal breathing. Deaths have been reported, including young people suffocated to death in Vancouver in 2003 and two adults suffocated to death in South Florida in 2006. In 1998, an Australian girl (age unknown) from Victoria fell unconscious and turned temporarily blue after inhaling the entire contents of a helium tank. Inhaling helium directly from pressurized cylinders or even cylinder filling valves is extremely dangerous, as the high flow rate and pressure can lead to barotrauma, a fatal injury to lung tissue. Death caused by helium is rare. The first reported case in the media was that of a 15-year-old Texas girl who died in 1998 from helium inhalation at a friend's party. In the United States, only two deaths were reported between 2000 and 2004, including a man who died in North Carolina from barotrauma in 2002. A young man suffocated in Vancouver in 2003, and a 27-year-old man in Australia had an embolism after inhaling gas from a cylinder in 2000. Since then, two adults suffocated to death in South Florida in 2006, several cases were recorded in 2009 and 2010, one with a California youth found with a bag over his head attached to a helium tank, and another with a teenager in Northern Ireland who died of suffocation. In Eagle Point, Oregon, a teenage girl died in 2012 from barotrauma at a party. A Michigan girl died of hypoxia at the end of that year. On February 4, 2015, it was revealed that on January 28, while taping the TV show for the Japanese girl group 3B Junior, a 12-year-old member of the group (whose name has been kept secret) suffered an embolism, passed out, and fell into a coma as a result of air bubbles blocking blood flow to the brain. after inhaling large amounts of helium. The incident was not made public until the following week. TV Asahi staff held an emergency press conference to announce that the girl had been taken to the hospital and was showing signs of rehabilitation such as eye and limb movement, but her consciousness had not yet recovered sufficiently. The police launched an investigation due to the neglect of security measures. The safety issues of cryogenic helium are similar to those of liquid nitrogen; its extremely low temperatures can lead to cold burns, and its liquid-to-gas expansion ratio can cause explosions unless pressure relief devices are installed. Helium gas containers at 5-10 K should be handled as if they contained liquid helium due to the rapid and significant thermal expansion that occurs when helium gas at less than 10 K is heated to room temperature. At high pressures (more than about 20 atm or two MPa), a mixture of helium and oxygen (heliox) can lead to high pressure nervous syndrome, a kind of reverse anesthetic effect; adding a small amount of nitrogen to the mixture may alleviate the problem.

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List of used literature:

Rayet, G. (1868) "Analyse spectral des protuberances observées, pendant l"éclipse totale de Soleil visible le 18 août 1868, à la presqu"île de Malacca" (Spectral analysis of the protuberances observed during the total solar eclipse, seen on 18 August 1868, from the Malacca peninsula), Comptes rendus … , 67: 757–759. From p. 758: "... je vis immédiatement une série de neuf lignes brillantes qui... me semblent devoir être assimilées aux lignes principales du spectre solaire, B, D, E, b, une ligne inconnue, F, et deux lignes du groupe G." (… I saw immediately a series of nine bright lines that… seemed to me should be classed as the principal lines of the solar spectrum, B, D, E, b, an unknown line, F, and two lines of the group G.