Liquid hydrogen: properties and applications. What is hydrogen? Which material contains a lot of hydrogen?

Hydrogen (H) is a very light chemical element, with a content of 0.9% by weight in the Earth's crust and 11.19% in water.

Characteristics of hydrogen

It is the first among gases in lightness. Under normal conditions, it is tasteless, colorless, and absolutely odorless. When it enters the thermosphere, it flies off into space due to its low weight.

In the entire universe, it is the most numerous chemical element (75% of the total mass of substances). So much so that many stars in outer space are made entirely of it. For example, the Sun. Its main component is hydrogen. And heat and light are the result of the release of energy when the nuclei of a material merge. Also in space there are entire clouds of its molecules of various sizes, densities and temperatures.

Physical properties

High temperature and pressure significantly change its qualities, but under normal conditions it:

It has high thermal conductivity when compared with other gases,

Non-toxic and poorly soluble in water,

With a density of 0.0899 g/l at 0°C and 1 atm.,

Turns into liquid at a temperature of -252.8°C

Becomes hard at -259.1°C.,

Specific heat of combustion 120.9.106 J/kg.

It requires high pressure and very low temperatures to turn into a liquid or solid. In a liquefied state, it is fluid and light.

Chemical properties

Under pressure and upon cooling (-252.87 degrees C), hydrogen acquires a liquid state, which is lighter in weight than any analogue. It takes up less space in it than in gaseous form.

It is a typical non-metal. In laboratories, it is produced by reacting metals (such as zinc or iron) with dilute acids. Under normal conditions it is inactive and reacts only with active non-metals. Hydrogen can separate oxygen from oxides, and reduce metals from compounds. It and its mixtures form hydrogen bonds with certain elements.

The gas is highly soluble in ethanol and in many metals, especially palladium. Silver does not dissolve it. Hydrogen can be oxidized during combustion in oxygen or air, and when interacting with halogens.

When it combines with oxygen, water is formed. If the temperature is normal, then the reaction proceeds slowly; if it is above 550°C, it explodes (it turns into detonating gas).

Finding hydrogen in nature

Although there is a lot of hydrogen on our planet, it is not easy to find in its pure form. A little can be found during volcanic eruptions, during oil production and where organic matter decomposes.

More than half of the total amount is in the composition with water. It is also included in the structure of oil, various clays, flammable gases, animals and plants (presence in every living cell is 50% by the number of atoms).

Hydrogen cycle in nature

Every year, a colossal amount (billions of tons) of plant residues decomposes in water bodies and soil, and this decomposition releases a huge mass of hydrogen into the atmosphere. It is also released during any fermentation caused by bacteria, combustion and, along with oxygen, participates in the water cycle.

Hydrogen Applications

The element is actively used by humanity in its activities, so we have learned to obtain it on an industrial scale for:

Meteorology, chemical production;

Margarine production;

As rocket fuel (liquid hydrogen);

Electric power industry for cooling electric generators;

Welding and cutting of metals.

A lot of hydrogen is used in the production of synthetic gasoline (to improve the quality of low-quality fuel), ammonia, hydrogen chloride, alcohols, and other materials. Nuclear energy actively uses its isotopes.

The drug “hydrogen peroxide” is widely used in metallurgy, the electronics industry, pulp and paper production, for bleaching linen and cotton fabrics, for the production of hair dyes and cosmetics, polymers and in medicine for the treatment of wounds.

The "explosive" nature of this gas can become a lethal weapon - a hydrogen bomb. Its explosion is accompanied by the release of a huge amount of radioactive substances and is destructive for all living things.

Contact of liquid hydrogen and skin can cause severe and painful frostbite.

Prevalence in nature. V. is widespread in nature; its content in the earth's crust (lithosphere and hydrosphere) is 1% by mass and 16% by number of atoms. V. is part of the most common substance on Earth - water (11.19% of V. by weight), in the composition of compounds that make up coal, oil, natural gases, clays, as well as animal and plant organisms (i.e., in the composition proteins, nucleic acids, fats, carbohydrates, etc.). In the free state, V. is extremely rare; it is found in small quantities in volcanic and other natural gases. Minor amounts of free hydrogen (0.0001% by number of atoms) are present in the atmosphere. In the near-Earth space, radiation forms the Earth's internal (“proton”) radiation belt in the form of a flow of protons. In space, V. is the most common element. In the form of plasma, it makes up about half the mass of the Sun and most stars, the bulk of the gases of the interstellar medium and gaseous nebulae. V. is present in the atmosphere of a number of planets and in comets in the form of free H2, methane CH4, ammonia NH3, water H2O, radicals such as CH, NH, OH, SiH, PH, etc. In the form of a flow of protons, energy is part of the corpuscular radiation of the Sun and cosmic rays.

Isotopes, atom and molecule. Ordinary vitriol consists of a mixture of two stable isotopes: light vitriol, or protium (1H), and heavy vitriol, or deuterium (2H, or D). In natural compounds, there are on average 6800 1H atoms per 1 2H atom. A radioactive isotope has been artificially produced - superheavy V., or tritium (3H, or T), with soft β-radiation and a half-life T1/2 = 12.262 years. In nature, tritium is formed, for example, from atmospheric nitrogen under the influence of cosmic ray neutrons; in the atmosphere it is negligibly small (4-10-15% of the total number of V atoms). An extremely unstable isotope 4H was obtained. The mass numbers of the isotopes 1H, 2H, 3H and 4H, respectively 1,2, 3 and 4, indicate that the nucleus of a protium atom contains only 1 proton, deuterium - 1 proton and 1 neutron, tritium - 1 proton and 2 neutrons, 4H - 1 proton and 3 neutrons. The large difference in the masses of the isotopes of V. determines a more noticeable difference in their physical and chemical properties than in the case of isotopes of other elements.

The V. atom has the simplest structure among the atoms of all other elements: it consists of a nucleus and one electron. The binding energy of an electron with a nucleus (ionization potential) is 13.595 eV. A neutral atom can also add a second electron, forming a negative ion H-; in this case, the binding energy of the second electron with a neutral atom (electron affinity) is 0.78 eV. Quantum mechanics makes it possible to calculate all possible energy levels of an atom and, therefore, give a complete interpretation of its atomic spectrum. The V atom is used as a model atom in quantum mechanical calculations of the energy levels of other, more complex atoms. Molecule B. H2 consists of two atoms connected by a covalent chemical bond. The energy of dissociation (i.e., decay into atoms) is 4.776 eV (1 eV = 1.60210-10-19 J). The interatomic distance at the equilibrium position of the nuclei is 0.7414-Å. At high temperatures, molecular hydrogen dissociates into atoms (the degree of dissociation at 2000°C is 0.0013, at 5000°C 0.95). Atomic V. is also formed in various chemical reactions (for example, by the action of Zn on hydrochloric acid). However, the existence of hydrogen in the atomic state lasts only a short time; the atoms recombine into H2 molecules.

Physical and chemical properties. V. is the lightest of all known substances (14.4 times lighter than air), density 0.0899 g/l at 0°C and 1 atm. Helium boils (liquefies) and melts (solidifies), respectively, at -252.6°C and -259.1°C (only helium has lower melting and boiling points). The critical temperature of water is very low (-240°C), so its liquefaction is fraught with great difficulties; critical pressure 12.8 kgf/cm2 (12.8 atm), critical density 0.0312 g/cm3. Of all gases, V. has the greatest thermal conductivity, equal to 0.174 W/(m-K) at 0°C and 1 atm, i.e. 4.16-0-4 cal/(s-cm-°C). The specific heat capacity of V. at 0°C and 1 atm Ср 14.208-103 J/(kg-K), i.e. 3.394 cal/(g-°C). V. is slightly soluble in water (0.0182 ml/g at 20°C and 1 atm), but well soluble in many metals (Ni, Pt, Pd, etc.), especially in palladium (850 volumes per 1 volume of Pd) . V.'s solubility in metals is related to its ability to diffuse through them; Diffusion through a carbon alloy (for example, steel) is sometimes accompanied by destruction of the alloy due to the interaction of carbon with carbon (so-called decarbonization). Liquid V. is very light (density at -253°C 0.0708 g/cm3) and fluid (viscosity at -253°C 13.8 spuaz).

In most compounds, V. exhibits a valence (more precisely, oxidation state) +1, like sodium and other alkali metals; usually it is considered as an analogue of these metals, leading 1 gram. Mendeleev's system. However, in metal hydrides, the B ion is negatively charged (oxidation state -1), i.e., the Na+H- hydride is structured similarly to the Na+Cl- chloride. This and some other facts (the similarity of the physical properties of V. and halogens, the ability of halogens to replace V. in organic compounds) give grounds to classify V. also in the VII group of the periodic table (for more details, see the Periodic Table of Elements). Under normal conditions, molecular V. is relatively little active, directly combining only with the most active of nonmetals (with fluorine, and in the light with chlorine). However, when heated, it reacts with many elements. Atomic V. has increased chemical activity compared to molecular. With oxygen, V. forms water: H2 + 1/2O2 = H2O with the release of 285.937-103 J/mol, i.e. 68.3174 kcal/mol of heat (at 25°C and 1 atm). At normal temperatures the reaction proceeds extremely slowly, above 550°C it explodes. The explosive limits of a hydrogen-oxygen mixture are (by volume) from 4 to 94% H2, and of a hydrogen-air mixture - from 4 to 74% H2 (a mixture of 2 volumes of H2 and 1 volume of O2 is called detonating gas). V. is used to reduce many metals, as it removes oxygen from their oxides:

CuO + H2 = Cu + H2O,
Fe3O4 + 4H2 = 3Fe + 4H2O, etc.
With halogens, V. forms hydrogen halides, for example:
H2 + Cl2 = 2HCl.

At the same time, V. explodes with fluorine (even in the dark and at -252°C), reacts with chlorine and bromine only when illuminated or heated, and with iodine only when heated. V. reacts with nitrogen to form ammonia: 3H2 + N2 = 2NH3 only on a catalyst and at elevated temperatures and pressures. When heated, V. reacts vigorously with sulfur: H2 + S = H2S (hydrogen sulfide), much more difficult with selenium and tellurium. V. can react with pure carbon without a catalyst only at high temperatures: 2H2 + C (amorphous) = CH4 (methane). V. reacts directly with certain metals (alkali, alkaline earth, etc.), forming hydrides: H2 + 2Li = 2LiH. Of great practical importance are the reactions of hydrogen with carbon monoxide, in which various organic compounds are formed, depending on temperature, pressure, and catalyst, for example HCHO, CH3OH, etc. (see Carbon monoxide). Unsaturated hydrocarbons react with hydrogen, becoming saturated, for example: CnH2n + H2 = CnH2n+2 (see Hydrogenation).

HYDROGEN, H (lat. hydrogenium; a. hydrogen; n. Wasserstoff; f. hydrogene; i. hidrogeno), is a chemical element of the periodic system of Mendeleev’s elements, which is simultaneously classified as groups I and VII, atomic number 1, atomic mass 1, 0079. Natural hydrogen has stable isotopes - protium (1 H), deuterium (2 H, or D) and radioactive - tritium (3 H, or T). For natural compounds, the average ratio D/H = (158±2).10 -6 The equilibrium content of 3 H on Earth is ~5.10 27 atoms.

Physical properties of hydrogen

Hydrogen was first described in 1766 by the English scientist G. Cavendish. Under normal conditions, hydrogen is a colorless, odorless, and tasteless gas. In nature, it is found in the free state in the form of H2 molecules. The dissociation energy of the H 2 molecule is 4.776 eV; ionization potential of the hydrogen atom is 13.595 eV. Hydrogen is the lightest substance known, at 0°C and 0.1 MPa 0.0899 kg/m 3 ; boiling t - 252.6°C, melting t - 259.1°C; critical parameters: t - 240°C, pressure 1.28 MPa, density 31.2 kg/m 3. The most thermally conductive of all gases is 0.174 W/(m.K) at 0°C and 1 MPa, specific heat capacity 14.208.10 3 J(kg.K).

Chemical properties of hydrogen

Liquid hydrogen is very light (density at -253°C is 70.8 kg/m 3) and fluid (at -253°C it is 13.8 cP). In most compounds, hydrogen exhibits an oxidation state of +1 (similar to alkali metals), less often -1 (similar to metal hydrides). Under normal conditions, molecular hydrogen is inactive; solubility in water at 20°C and 1 MPa 0.0182 ml/g; highly soluble in metals - Ni, Pt, Pd, etc. With oxygen it forms water with the release of heat 143.3 MJ/kg (at 25°C and 0.1 MPa); at 550°C and above the reaction is accompanied by an explosion. When interacting with fluorine and chlorine, reactions also occur explosively. The main hydrogen compounds: H 2 O, ammonia NH 3, hydrogen sulfide H 2 S, CH 4, metal and halogen hydrides CaH 2, HBr, Hl, as well as organic compounds C 2 H 4, HCHO, CH 3 OH, etc.

Hydrogen in nature

Hydrogen is a widespread element in nature, its content is 1% (by weight). The main reservoir of hydrogen on Earth is water (11.19%, by mass). Hydrogen is one of the main components of all natural organic compounds. In a free state, it is present in volcanic and other natural gases, in (0.0001%, by number of atoms). It makes up the bulk of the mass of the Sun, stars, interstellar gas, and gas nebulae. In the atmospheres of planets it is present in the form of H 2, CH 4, NH 3, H 2 O, CH, NHOH, etc. It is part of the corpuscular radiation of the Sun (proton flows) and cosmic rays (electron flows).

Production and use of hydrogen

Raw materials for the industrial production of hydrogen are oil refinery gases, gasification products, etc. The main methods for producing hydrogen are: the reaction of hydrocarbons with water vapor, partial oxidation of hydrocarbons, oxide conversion, electrolysis of water. Hydrogen is used for the production of ammonia, alcohols, synthetic gasoline, hydrochloric acid, hydrotreating of petroleum products, and cutting metals with a hydrogen-oxygen flame.

Hydrogen is a promising gaseous fuel. Deuterium and tritium have found application in nuclear energy.

Hydrogen storage.

Gladysheva Marina Alekseevna, 10A, school No. 75, Chernogolovka. Report at the conference "Start in Science", MIPT, 2004.

The attractiveness of hydrogen as a universal energy carrier is determined by its environmental friendliness, flexibility and efficiency of energy conversion processes involving its participation. Technologies for multi-scale hydrogen production are quite well developed and have an almost unlimited raw material base. However, the low density of hydrogen gas, the low temperature of its liquefaction, as well as the high explosion hazard, combined with a negative impact on the properties of structural materials, bring to the fore the problems of developing effective and safe hydrogen storage systems - these are the problems that are currently hindering the development of hydrogen energy and technology .

In accordance with the classification of the US Department of Energy, hydrogen fuel storage methods can be divided into 2 groups:

The first group includes physical methods that use physical processes (mainly compression or liquefaction) to convert hydrogen gas into a compact state. Hydrogen stored using physical methods consists of H 2 molecules , weakly interacting with the storage environment. The following physical methods for storing hydrogen have been implemented today:

Compressed hydrogen gas:

gas cylinders;

stationary massive storage systems, including underground tanks;

storage in pipelines;

glass microspheres.

Liquid hydrogen: stationary and transport cryogenic containers.

IN chemical methods, hydrogen storage is ensured by physical or chemical processes of its interaction with certain materials. These methods are characterized by the strong interaction of molecular or atomic hydrogen with the material of the storage medium. This group of methods mainly includes the following:

Adsorption:

zeolites and related compounds;

Activated carbon;

hydrocarbon nanomaterials.

Absorption per volume of material(metal hydrides)

Chemical interaction:

alonates;

fullerenes and organic hydrides;

ammonia;

sponge iron;

water-reactive alloys based on aluminum and silicon.

Hydrogen gas storage is no more complex problem than natural gas storage. In practice, gas tanks, natural underground reservoirs (aquifers, depleted oil and gas fields), and storage facilities created by underground atomic explosions are used for this purpose. The fundamental possibility of storing hydrogen gas in salt caverns created by dissolving salt with water through boreholes has been proven.

To store hydrogen gas at pressures up to 100 MPa, welded vessels with two- or multi-layer walls are used. The inner wall of such a vessel is made of austenitic stainless steel or other material compatible with hydrogen under high pressure conditions, the outer layers are made of high-strength steels. For these purposes, seamless thick-walled vessels made of low-carbon steels designed for pressures of up to 40 - 70 MPa are also used.

The storage of hydrogen gas in gas holders with a water pool (wet gas holders), constant pressure piston gas holders (dry gas holders), and constant volume gas holders (high pressure tanks) has become widespread. Cylinders are used to store small quantities of hydrogen.

It should be borne in mind that wet as well as dry (piston) gas tanks of welded construction do not have sufficient tightness. According to the technical conditions, hydrogen leakage is allowed during normal operation of wet gas tanks with a capacity of up to 3000 m3 3 – about 1.65%, and with a capacity from 3000 m 3 and more - about 1.1% per day (based on the nominal volume of the gas tank).

One of the most promising ways to store large quantities of hydrogen is to store it in aquifers. Annual losses with this storage method range from 1 to 3%. This amount of losses is confirmed by the experience of natural gas storage.

Hydrogen gas can be stored and transported in steel vessels under pressure up to 20 MPa. Such containers can be transported to the point of consumption on automobile or railway platforms, both in standard containers and in specially designed containers.

For storage and transportation of small quantities of compressed hydrogen at temperatures from –50 to +60 0 C use steel seamless cylinders of small capacity up to 12 dm 3 and average capacity 20 – 50 dm 3 with working pressure up to 20 MPa. The valve body is made of brass. The cylinders are painted dark green and have the inscription “Hydrogen” in red.

Hydrogen storage cylinders are quite simple and compact. However, to store 2 kg N 2 bolts weighing 33 kg are required. Progress in materials science makes it possible to reduce the mass of the cylinder material to 20 kg per 1 kg of hydrogen, and in the future it is possible to reduce it to 8–10 kg. So far, the mass of hydrogen when stored in cylinders is approximately 2–3% of the mass of the cylinder itself.

Large quantities of hydrogen can be stored in large pressurized gas tanks. Gas tanks are usually made of carbon steel. The working pressure in them usually does not exceed 10 MPa. Due to the low density of hydrogen gas, storing it in such containers is beneficial only in relatively small quantities. Increasing the pressure above the specified value, for example, to hundreds of mega Pascals, firstly, causes difficulties associated with hydrogen corrosion of carbon steels, and, secondly, leads to a significant increase in the cost of such containers.

For storing very large quantities of hydrogen, a cost-effective method is to store depleted gas and aquifers. There are more than 300 underground gas storage facilities in the United States.

Hydrogen gas in very large quantities is stored in salt caverns 365 m deep at a hydrogen pressure of 5 MPa, in porous water-filled structures containing up to 20 10 6 m 3 hydrogen.

Experience of long-term storage (more than 10 years) in underground gas storage facilities of gas containing 50% hydrogen has shown the full possibility of its storage without noticeable leaks. Layers of clay soaked in water can provide hermetically sealed storage due to the weak dissolution of hydrogen in water.

Liquid hydrogen storage

Among the many unique properties of hydrogen that are important to consider when storing it in liquid form, one is especially important. Hydrogen in the liquid state is found in a narrow temperature range: from the boiling point of 20K to the freezing point of 17K, when it turns into a solid state. If the temperature rises above its boiling point, hydrogen instantly changes from liquid to gas.

To prevent local overheating, vessels that are filled with liquid hydrogen should be pre-cooled to a temperature close to the boiling point of hydrogen, only then can they be filled with liquid hydrogen. To do this, cooling gas is passed through the system, which is associated with high consumption of hydrogen to cool the container.

The transition of hydrogen from liquid to gaseous state is associated with inevitable losses from evaporation. The cost and energy content of the evaporated gas is significant. Therefore, organizing the use of this gas from an economic and safety point of view is necessary. According to the conditions for safe operation of a cryogenic vessel, it is necessary that after reaching the maximum operating pressure in the container, the gas space is at least 5%.

There are a number of requirements for liquid hydrogen storage tanks:

the design of the tank must ensure strength and reliability, long-term safe operation;

the consumption of liquid hydrogen for pre-cooling the storage facility before filling it with liquid hydrogen should be minimal;

The storage tank must be equipped with a means for rapid filling with liquid hydrogen and rapid dispensing of the stored product.

The main part of the cryogenic hydrogen storage system is thermally insulated vessels, the mass of which is approximately 4 - 5 times less per 1 kg of stored hydrogen than with cylinder storage under high pressure. In cryogenic storage systems for liquid hydrogen, 1 kg of hydrogen accounts for 6–8 kg of the mass of a cryogenic vessel, and in terms of volumetric characteristics, cryogenic vessels correspond to the storage of gaseous hydrogen under a pressure of 40 MPa.

Liquid hydrogen is stored in large quantities in special storage facilities with a volume of up to 5 thousand m 3 . Large spherical storage facility for liquid hydrogen with a volume of 2850 m 3 has an internal diameter of the aluminum sphere of 17.4 m 3 .

Storage and transportation of hydrogen in a chemically bound state

The advantages of storing and transporting hydrogen in the form of ammonia, methanol, ethanol over long distances are the high density of the volumetric hydrogen content. However, in these forms of hydrogen storage, the storage medium is used once. The liquefaction temperature of ammonia is 239.76 K, the critical temperature is 405 K, so at normal temperature, ammonia liquefies at a pressure of 1.0 MPa and can be transported through pipes and stored in liquid form. Basic The ratios are given below:

1 m 3 N 2 (g) » 0.66 m 3 NH 3 » 0?75 dm 3 H 2 (l);

1 t NH 3 » 1975 m 3 N 2 + 658 m 3 N 2 – 3263 MJ;

2NH 3 ?N 2 + 3H 2 – 92 kJ.

Dissociators for the decomposition of ammonia (crackers), which occurs at temperatures of approximately 1173 - 1073 K and atmospheric pressure, use a spent iron catalyst to synthesize ammonia. To produce one kg of hydrogen, 5.65 kg of ammonia is consumed. As for the heat consumption for the dissociation of ammonia when using this heat from the outside, the heat of combustion of the resulting hydrogen can be up to 20% higher than the heat of combustion of the ammonia used in the decomposition process. If hydrogen obtained in the process is used for the dissociation process, then the efficiency of such a process (the ratio of the heat of the resulting gas to the heat of combustion of the consumed ammonia) does not exceed 60 - 70%.

Hydrogen from methanol can be obtained according to two schemes: either by catalytic decomposition:

CH 3 OH? CO+2H 2 – 90 kJ

followed by catalytic conversion of CO or catalytic steam conversion in one stage:

H 2 O + CH 3 OH? CO 2 + 3H 2 – 49 kJ.

Typically, the process uses a zinc-chromium catalyst for methanol synthesis. The process occurs at 573 – 673 K. Methanol can be used as fuel for conversion processes. In this case, the efficiency of the hydrogen production process is 65–70% (the ratio of the heat of the produced hydrogen to the heat of combustion of the consumed methanol); if heat for the process of producing hydrogen is supplied from the outside, the heat of combustion of hydrogen obtained by catalytic decomposition is 22%, and that of hydrogen obtained by steam reforming is 15% higher than the heat of combustion of consumed methanol.

It should be added to the above that when creating an energy-technological scheme using waste heat and the use of hydrogen obtained from methanol, ammonia or ethanol, it is possible to obtain a process efficiency higher than when using these products as synthetic liquid fuels. Thus, with direct combustion of methanol and a gas turbine unit, the efficiency is 35%, when, due to the heat of exhaust gases, evaporation and catalytic conversion of methanol and combustion of the CO + H mixture are carried out 2 The efficiency increases to 41.30%, and when carrying out steam reforming and combustion of the resulting hydrogen - up to 41.9%.

Hydride hydrogen storage system

By storing hydrogen in hydride form, there is no need for bulky and heavy cylinders required when storing compressed hydrogen gas, or difficult to manufacture and expensive vessels for storing liquid hydrogen. When storing hydrogen in the form of hydrides, the volume of the system is reduced by approximately 3 times compared to the volume of storage in cylinders. Hydrogen transportation is simplified. There are no costs for conversion and liquefaction of hydrogen.

Hydrogen can be obtained from metal hydrides by two reactions: hydrolysis and dissociation.

By hydrolysis it is possible to obtain twice as much hydrogen as is present in the hydride. However, this process is practically irreversible. The method of producing hydrogen by thermal dissociation of a hydride makes it possible to create hydrogen batteries, for which a slight change in temperature and pressure in the system causes a significant change in the equilibrium of the hydride formation reaction.

Stationary devices for storing hydrogen in the form of hydrides do not have strict restrictions on mass and volume, so the limiting factor in the choice of a particular hydride will, in all likelihood, be its cost. For some applications, vanadium hydride may be useful, since it dissociates well at a temperature close to 270 K. Magnesium hydride is relatively inexpensive, but has a relatively high dissociation temperature of 560 - 570 K and a high heat of formation. The iron-titanium alloy is relatively inexpensive, and its hydride dissociates at temperatures of 320 - 370 K with a low heat of formation. The use of hydrides has significant safety advantages. A damaged hydrogen hydride vessel poses significantly less danger than a damaged liquid hydrogen tank or pressure vessel filled with hydrogen.

Currently, at the Institute of Chemical Physics of the Russian Academy of Sciences in Chernogolovka, work is underway to create hydrogen batteries based on metal hydrides.

Bibliography :

1. Directory. "Hydrogen. Properties, receipt, storage, transportation, application.” Moscow “Chemistry” - 1989

2. “Review of hydrogen storage methods.” Institute of Materials Science Problems of the National Academy of Sciences of Ukraine. http://shp.by.ru/sci/fullerene/rorums/ichms/2003/

It has its own specific position in the periodic table, which reflects the properties it exhibits and speaks about its electronic structure. However, among all of them there is one special atom that occupies two cells at once. It is located in two groups of elements that are completely opposite in their properties. This is hydrogen. Such features make it unique.

Hydrogen is not just an element, but also a simple substance, as well as an integral part of many complex compounds, a biogenic and organogenic element. Therefore, let us consider its characteristics and properties in more detail.

Hydrogen as a chemical element

Hydrogen is an element of the first group of the main subgroup, as well as the seventh group of the main subgroup in the first minor period. This period consists of only two atoms: helium and the element we are considering. Let us describe the main features of the position of hydrogen in the periodic table.

1. The atomic number of hydrogen is 1, the number of electrons is the same, and, accordingly, the number of protons is the same. Atomic mass - 1.00795. There are three isotopes of this element with mass numbers 1, 2, 3. However, the properties of each of them are very different, since an increase in mass even by one for hydrogen is immediately double.
2. The fact that it contains only one electron on its outer surface allows it to successfully exhibit both oxidizing and reducing properties. In addition, after donating an electron, it remains with a free orbital, which takes part in the formation of chemical bonds according to the donor-acceptor mechanism.
3. Hydrogen is a strong reducing agent. Therefore, its main place is considered to be the first group of the main subgroup, where it heads the most active metals - alkali.
4. However, when interacting with strong reducing agents, such as metals, it can also be an oxidizing agent, accepting an electron. These compounds are called hydrides. According to this feature, it heads the subgroup of halogens with which it is similar.
5. Due to its very small atomic mass, hydrogen is considered the lightest element. In addition, its density is also very low, so it is also a benchmark for lightness.

Thus, it is obvious that the hydrogen atom is a completely unique element, unlike all other elements. Consequently, its properties are also special, and the simple and complex substances formed are very important. Let's consider them further.

Simple substance

If we talk about this element as a molecule, then we must say that it is diatomic. That is, hydrogen (a simple substance) is a gas. Its empirical formula will be written as H2, and its graphical formula will be written through a single sigma H-H relationship. The mechanism of bond formation between atoms is covalent nonpolar.

1. Steam methane reforming.
2. Coal gasification - the process involves heating coal to 1000 0 C, resulting in the formation of hydrogen and high-carbon coal.
3. Electrolysis. This method can only be used for aqueous solutions of various salts, since the melts do not lead to a discharge of water at the cathode.

Laboratory methods for producing hydrogen:

1. Hydrolysis of metal hydrides.
2. The effect of dilute acids on active metals and medium activity.
3. Interaction of alkali and alkaline earth metals with water.

To collect the hydrogen produced, you must hold the test tube upside down. After all, this gas cannot be collected in the same way as, for example, carbon dioxide. This is hydrogen, it is much lighter than air. It evaporates quickly, and in large quantities it explodes when mixed with air. Therefore, the test tube should be inverted. After filling it, it must be closed with a rubber stopper.

To check the purity of the collected hydrogen, you should bring a lit match to the neck. If the clap is dull and quiet, it means the gas is clean, with minimal air impurities. If it is loud and whistling, it is dirty, with a large proportion of foreign components.

Areas of use

When hydrogen is burned, such a large amount of energy (heat) is released that this gas is considered the most profitable fuel. Moreover, it is environmentally friendly. However, to date its application in this area is limited. This is due to ill-conceived and unsolved problems of synthesizing pure hydrogen, which would be suitable for use as fuel in reactors, engines and portable devices, as well as residential heating boilers.

After all, the methods for producing this gas are quite expensive, so first it is necessary to develop a special synthesis method. One that will allow you to obtain the product in large volumes and at minimal cost.

There are several main areas in which the gas we are considering is used.

1. Chemical syntheses. Hydrogenation is used to produce soaps, margarines, and plastics. With the participation of hydrogen, methanol and ammonia, as well as other compounds, are synthesized.
2. In the food industry - as additive E949.
3. Aviation industry (rocket science, aircraft manufacturing).
4. Electric power industry.
5. Meteorology.
6. Environmentally friendly fuel.

Obviously, hydrogen is as important as it is abundant in nature. The various compounds it forms play an even greater role.

Hydrogen compounds

These are complex substances containing hydrogen atoms. There are several main types of such substances.

1. Hydrogen halides. The general formula is HHal. Of particular importance among them is hydrogen chloride. It is a gas that dissolves in water to form a solution of hydrochloric acid. This acid is widely used in almost all chemical syntheses. Moreover, both organic and inorganic. Hydrogen chloride is a compound with the empirical formula HCL and is one of the largest produced in our country annually. Hydrogen halides also include hydrogen iodide, hydrogen fluoride and hydrogen bromide. They all form the corresponding acids.
2. Volatile Almost all of them are quite poisonous gases. For example, hydrogen sulfide, methane, silane, phosphine and others. At the same time, they are very flammable.
3. Hydrides are compounds with metals. They belong to the class of salts.
4. Hydroxides: bases, acids and amphoteric compounds. They necessarily contain hydrogen atoms, one or more. Example: NaOH, K 2, H 2 SO 4 and others.
5. Hydrogen hydroxide. This compound is better known as water. Another name is hydrogen oxide. The empirical formula looks like this - H 2 O.
6. Hydrogen peroxide. This is a strong oxidizing agent, the formula of which is H 2 O 2.
7. Numerous organic compounds: hydrocarbons, proteins, fats, lipids, vitamins, hormones, essential oils and others.

It is obvious that the variety of compounds of the element we are considering is very large. This once again confirms its high importance for nature and humans, as well as for all living beings.

- this is the best solvent

As mentioned above, the common name for this substance is water. Consists of two hydrogen atoms and one oxygen, connected by covalent polar bonds. The water molecule is a dipole, this explains many of the properties it exhibits. In particular, it is a universal solvent.

It is in the aquatic environment that almost all chemical processes occur. Internal reactions of plastic and energy metabolism in living organisms are also carried out using hydrogen oxide.

Water is rightfully considered the most important substance on the planet. It is known that no living organism can live without it. On Earth it can exist in three states of aggregation:

• liquid;
• gas (steam);
• solid (ice).

Depending on the isotope of hydrogen included in the molecule, three types of water are distinguished.

1. Light or protium. An isotope with mass number 1. Formula - H 2 O. This is the usual form that all organisms use.
2. Deuterium or heavy, its formula is D 2 O. Contains the isotope 2 H.
3. Super heavy or tritium. The formula looks like T 3 O, isotope - 3 H.

The reserves of fresh protium water on the planet are very important. There is already a shortage of it in many countries. Methods are being developed for treating salt water to produce drinking water.

Hydrogen peroxide is a universal remedy

This compound, as mentioned above, is an excellent oxidizing agent. However, with strong representatives he can also behave as a restorer. In addition, it has a pronounced bactericidal effect.

Another name for this compound is peroxide. It is in this form that it is used in medicine. A 3% solution of crystalline hydrate of the compound in question is a medical medicine that is used to treat small wounds for the purpose of disinfecting them. However, it has been proven that this increases the healing time of the wound.

Hydrogen peroxide is also used in rocket fuel, in industry for disinfection and bleaching, and as a foaming agent for the production of appropriate materials (foam, for example). Additionally, peroxide helps clean aquariums, bleach hair, and whiten teeth. However, it causes harm to tissues, so it is not recommended by specialists for these purposes.