Hydrogen H is the most common element in the Universe (about 75% by mass), on Earth it is the ninth most common element. The most important natural hydrogen compound is water.
Hydrogen ranks first in the periodic table (Z = 1). It has the simplest structure of an atom: the nucleus of an atom is 1 proton, surrounded by an electron cloud consisting of 1 electron.
Under certain conditions, hydrogen exhibits metallic properties(donates an electron), in others - non-metallic (accepts an electron).
Hydrogen isotopes are found in nature: 1H - protium (the nucleus consists of one proton), 2H - deuterium (D - the nucleus consists of one proton and one neutron), 3H - tritium (T - the nucleus consists of one proton and two neutrons).

The simple substance hydrogen

The hydrogen molecule consists of two atoms linked by a non-polar covalent bond.
Physical properties. Hydrogen is a colorless, non-toxic, odorless and tasteless gas. The hydrogen molecule is not polar. Therefore, the forces of intermolecular interaction in gaseous hydrogen are small. This manifests itself in low temperatures boiling (-252.6 0С) and melting (-259.2 0С).
Hydrogen is lighter than air, D (in air) = 0.069; slightly soluble in water (2 volumes of H2 dissolve in 100 volumes of H2O). Therefore, hydrogen, when produced in the laboratory, can be collected by air or water displacement methods.

Getting hydrogen

In the laboratory:

1. Action of dilute acids on metals:
Zn +2HCl → ZnCl 2 +H 2

2. Interaction of alkaline and sh-z metals with water:
Ca + 2H 2 O → Ca (OH) 2 + H 2

3. Hydrolysis of hydrides: metal hydrides are easily decomposed by water with the formation of the corresponding alkali and hydrogen:
NaH + H 2 O → NaOH + H 2
CaH 2 + 2H 2 O \u003d Ca (OH) 2 + 2H 2

4. The action of alkalis on zinc or aluminum or silicon:
2Al + 2NaOH + 6H 2 O → 2Na + 3H 2
Zn + 2KOH + 2H 2 O → K 2 + H 2
Si + 2NaOH + H 2 O → Na 2 SiO 3 + 2H 2

5. Water electrolysis. To increase the electrical conductivity of water, an electrolyte is added to it, for example, NaOH, H 2 SO 4 or Na 2 SO 4. At the cathode, 2 volumes of hydrogen are formed, at the anode - 1 volume of oxygen.
2H 2 O → 2H 2 + O 2

Industrial production of hydrogen

1. Conversion of methane with steam, Ni 800 °C (cheapest):
CH 4 + H 2 O → CO + 3 H 2
CO + H 2 O → CO 2 + H 2

In total:
CH 4 + 2 H 2 O → 4 H 2 + CO 2

2. Water vapor through hot coke at 1000 o C:
C + H 2 O → CO + H 2
CO + H 2 O → CO 2 + H 2

The resulting carbon monoxide (IV) is absorbed by water, in this way 50% of industrial hydrogen is obtained.

3. By heating methane to 350°C in the presence of an iron or nickel catalyst:
CH 4 → C + 2H 2

4. Electrolysis of aqueous solutions of KCl or NaCl as a by-product:
2H 2 O + 2NaCl → Cl 2 + H 2 + 2NaOH

Chemical properties of hydrogen

  • In compounds, hydrogen is always monovalent. It has an oxidation state of +1, but in metal hydrides it is -1.
  • The hydrogen molecule consists of two atoms. The emergence of a bond between them is explained by the formation of a generalized pair of electrons H: H or H 2
  • Due to this generalization of electrons, the H 2 molecule is more energetically stable than its individual atoms. To break a molecule into atoms in 1 mole of hydrogen, it is necessary to expend an energy of 436 kJ: H 2 \u003d 2H, ∆H ° \u003d 436 kJ / mol
  • This explains the relatively low activity of molecular hydrogen at ordinary temperature.
  • With many non-metals, hydrogen forms gaseous compounds such as RN 4, RN 3, RN 2, RN.

1) Forms hydrogen halides with halogens:
H 2 + Cl 2 → 2HCl.
At the same time, it explodes with fluorine, reacts with chlorine and bromine only when illuminated or heated, and with iodine only when heated.

2) With oxygen:
2H 2 + O 2 → 2H 2 O
with heat release. At ordinary temperatures, the reaction proceeds slowly, above 550 ° C - with an explosion. A mixture of 2 volumes of H 2 and 1 volume of O 2 is called explosive gas.

3) When heated, it reacts vigorously with sulfur (much more difficult with selenium and tellurium):
H 2 + S → H 2 S (hydrogen sulfide),

4) With nitrogen with the formation of ammonia only on the catalyst and at elevated temperatures and pressures:
ZN 2 + N 2 → 2NH 3

5) With carbon at high temperatures:
2H 2 + C → CH 4 (methane)

6) Forms hydrides with alkali and alkaline earth metals (hydrogen is an oxidizing agent):
H 2 + 2Li → 2LiH
in metal hydrides, the hydrogen ion is negatively charged (oxidation state -1), that is, the hydride Na + H - is built like chloride Na + Cl -

With complex substances:

7) With metal oxides (used to restore metals):
CuO + H 2 → Cu + H 2 O
Fe 3 O 4 + 4H 2 → 3Fe + 4H 2 O

8) with carbon monoxide (II):
CO + 2H 2 → CH 3 OH
Synthesis - gas (a mixture of hydrogen and carbon monoxide) is of great practical importance, as depending on temperature, pressure and catalyst, various organic compounds, such as HCHO, CH 3 OH and others.

9) Unsaturated hydrocarbons react with hydrogen, turning into saturated:
C n H 2n + H 2 → C n H 2n+2.


The most common chemical element in the universe is hydrogen. This is a kind of reference point, because in the periodic table its atomic number is equal to one. Humanity hopes to be able to learn more about it as one of the most possible vehicles in the future. Hydrogen is the simplest, lightest, most common element, it is abundant everywhere - seventy-five percent of the total mass of matter. It is in any star, especially a lot of hydrogen in gas giants. Its role in stellar fusion reactions is key. Without hydrogen, there is no water, which means there is no life. Everyone remembers that a water molecule contains one oxygen atom, and two atoms in it are hydrogen. This is the well-known formula H 2 O.

How we use it

Hydrogen was discovered in 1766 by Henry Cavendish while analyzing the oxidation reaction of a metal. After several years of observation, he realized that in the process of burning hydrogen, water is formed. Previously, scientists isolated this element, but did not consider it independent. In 1783, hydrogen was given the name hydrogen (translated from the Greek "hydro" - water, and "gene" - to give birth). The element that generates water is hydrogen. It is a gas whose molecular formula is H 2 . If the temperature is close to room temperature and the pressure is normal, this element is imperceptible. Hydrogen can't even be caught human organs senses - it is tasteless, colorless, odorless. But under pressure and at a temperature of -252.87 C (very cold!) This gas liquefies. This is how it is stored, since in the form of a gas it takes up much more space. It is liquid hydrogen that is used as rocket fuel.

Hydrogen can become solid, metallic, but for this, superhigh pressure is needed, and this is what the most prominent scientists, physicists and chemists, are doing now. Already now this element serves as an alternative fuel for transport. Applying it is similar to how an engine works. internal combustion: When hydrogen is burned, a lot of its chemical energy is released. A method for creating a fuel cell based on it has also been practically developed: when combined with oxygen, a reaction occurs, and through this, water and electricity are formed. It is possible that transport will soon "switch" instead of gasoline to hydrogen - a lot of automakers are interested in creating alternative combustible materials, and there are some successes. But a purely hydrogen engine is still in the future, there are many difficulties. However, the advantages are such that the creation of a fuel tank with solid hydrogen is in full swing, and scientists and engineers are not going to retreat.

Basic information

Hydrogenium (lat.) - hydrogen, the first serial number in the periodic table, is designated H. The hydrogen atom has a mass of 1.0079, it is a gas that under normal conditions has no taste, no smell, no color. Chemists since the sixteenth century have described a certain combustible gas, denoting it in different ways. But it turned out for everyone under the same conditions - when acid acts on the metal. Hydrogen, even by Cavendish himself, for many years was simply called "combustible air." Only in 1783, Lavoisier proved that water has a complex composition, through synthesis and analysis, and four years later he gave his "combustible air" modern name. The root of this compound word is widely used when it is necessary to name hydrogen compounds and any processes in which it participates. For example, hydrogenation, hydride and the like. A Russian name proposed in 1824 by M. Solovyov.

In nature, the distribution of this element has no equal. In the lithosphere and hydrosphere of the earth's crust, its mass is one percent, but hydrogen atoms are as much as sixteen percent. The most common water on Earth, and 11.19% by weight in it is hydrogen. Also, it is certainly present in almost all compounds that make up oil, coal, all natural gases, clay. There is hydrogen in all organisms of plants and animals - in the composition of proteins, fats, nucleic acids, carbohydrates, and so on. The free state for hydrogen is not typical and almost never occurs - there is very little of it in natural and volcanic gases. A very negligible amount of hydrogen in the atmosphere - 0.0001%, in terms of the number of atoms. On the other hand, whole streams of protons represent hydrogen in the near-Earth space, which makes up the inner radiation belt of our planet.

Space

In space, no element is as common as hydrogen. The volume of hydrogen in the composition of the elements of the Sun is more than half of its mass. Most stars form hydrogen in the form of plasma. The main part of various gases of nebulae and the interstellar medium also consists of hydrogen. It is present in comets, in the atmosphere of a number of planets. Naturally, not in its pure form, either as free H 2, or as methane CH 4, or as ammonia NH 3, even as water H 2 O. Very often there are radicals CH, NH, SiN, OH, PH and the like. As a stream of protons, hydrogen is part of the corpuscular solar radiation and cosmic rays.

In ordinary hydrogen, a mixture of two stable isotopes is light hydrogen (or protium 1 H) and heavy hydrogen (or deuterium - 2 H or D). There are other isotopes: radioactive tritium - 3 H or T, otherwise - superheavy hydrogen. And also very unstable 4 N. In nature, a hydrogen compound contains isotopes in such proportions: there are 6800 protium atoms per deuterium atom. Tritium is formed in the atmosphere from nitrogen, which is affected by cosmic ray neutrons, but negligible. What do the mass numbers of isotopes mean? The number indicates that the protium nucleus has only one proton, while deuterium has not only a proton, but also a neutron in the nucleus of an atom. Tritium has two neutrons in the nucleus for one proton. But 4 N contains three neutrons per proton. Therefore, the physical and chemical properties of hydrogen isotopes are very different compared to the isotopes of all other elements - the mass difference is too large.

Structure and physical properties

In terms of structure, the hydrogen atom is the simplest in comparison with all other elements: one nucleus - one electron. Ionization potential - the binding energy of the nucleus with the electron - 13.595 electron volts (eV). It is precisely because of the simplicity of this structure that the hydrogen atom is a convenient model in quantum mechanics when it is necessary to calculate the energy levels of more complex atoms. In the H 2 molecule, there are two atoms that are connected by a chemical covalent bond. The decay energy is very high. Atomic hydrogen can be formed in chemical reactions such as zinc and hydrochloric acid. However, interaction with hydrogen practically does not occur - the atomic state of hydrogen is very short, the atoms immediately recombine into H 2 molecules.

From a physical point of view, hydrogen is lighter than all known substances - more than fourteen times lighter than air (remember flying balloons on holidays - they have just hydrogen inside). However, helium can boil, liquefy, melt, solidify, and only helium boils and melts at lower temperatures. It is difficult to liquefy it, you need a temperature below -240 degrees Celsius. But it has a very high thermal conductivity. It almost does not dissolve in water, but metal interacts perfectly with hydrogen - it dissolves in almost all, best of all in palladium (850 volumes are spent on one volume of hydrogen). Liquid hydrogen is light and fluid, and when dissolved in metals, it often destroys alloys due to interaction with carbon (steel, for example), diffusion, decarbonization occurs.

Chemical properties

In compounds, for the most part, hydrogen shows an oxidation state (valence) of +1, like sodium and other alkali metals. He is considered as their analogue, standing at the head of the first group of the Mendeleev system. But the hydrogen ion in metal hydrides is negatively charged, with an oxidation state of -1. Also, this element is close to halogens, which are even able to replace it in organic compounds. This means that hydrogen can also be attributed to the seventh group of the Mendeleev system. Under normal conditions, hydrogen molecules do not differ in activity, combining only with the most active non-metals: it is good with fluorine, and if it is light, with chlorine. But when heated, hydrogen becomes different - it reacts with many elements. Atomic hydrogen, compared to molecular hydrogen, is very active chemically, so water is formed in connection with oxygen, and energy and heat are released along the way. At room temperature, this reaction is very slow, but when heated above five hundred and fifty degrees, an explosion is obtained.

Hydrogen is used to reduce metals, because it takes away oxygen from their oxides. With fluorine, hydrogen forms an explosion even in the dark and at minus two hundred and fifty-two degrees Celsius. Chlorine and bromine excite hydrogen only when heated or illuminated, and iodine only when heated. Hydrogen and nitrogen form ammonia (this is how most fertilizers are made). When heated, it very actively interacts with sulfur, and hydrogen sulfide is obtained. With tellurium and selenium it is difficult to cause a reaction of hydrogen, but with pure carbon the reaction occurs at very high temperatures, and methane is obtained. With carbon monoxide, hydrogen forms various organic compounds, pressure, temperature, catalysts influence here, and all this is of great practical importance. In general, the role of hydrogen, as well as its compounds, is exceptionally great, since it gives acidic properties to protic acids. Hydrogen bonds are formed with many elements, affecting the properties of both inorganic and organic compounds.

Getting and using

Hydrogen is obtained on an industrial scale from natural gases - combustible, coke oven, oil refining gases. It can also be obtained by electrolysis where electricity is not too expensive. However, the most important method of hydrogen production is the catalytic reaction of hydrocarbons, mostly methane, with water vapor, when conversion is obtained. The method of oxidizing hydrocarbons with oxygen is also widely used. Extraction of hydrogen from natural gas is the cheapest way. The other two are the use of coke oven gas and refinery gas - hydrogen is released when the other components are liquefied. They are more easily liquefied, and for hydrogen, as we remember, you need -252 degrees.

Hydrogen peroxide is very popular. Treatment with this solution is used very often. The molecular formula H 2 O 2 is unlikely to be named by all those millions of people who want to be blondes and lighten their hair, as well as those who love cleanliness in the kitchen. Even those who treat scratches from playing with a kitten often do not realize that they are using hydrogen treatment. But everyone knows the story: since 1852, hydrogen for a long time used in aeronautics. The airship invented by Henry Giffard was based on hydrogen. They were called zeppelins. The zeppelins were forced out of the sky by the rapid development of aircraft construction. In 1937, there was a major accident when the Hindenburg airship burned down. After this incident, zeppelins were never used again. But at the end of the eighteenth century, the spread balloons filled with hydrogen was ubiquitous. In addition to the production of ammonia, today hydrogen is needed for the manufacture of methyl alcohol and other alcohols, gasoline, hydrogenated heavy fuel oil and solid fuels. You can not do without hydrogen when welding, when cutting metals - it can be oxygen-hydrogen and atomic-hydrogen. And tritium and deuterium give life nuclear power. This, as we remember, isotopes of hydrogen.

Neumyvakin

Hydrogen as chemical element so good that he couldn't help but have his own fans. Ivan Pavlovich Neumyvakin - doctor of medical sciences, professor, laureate of the State Prize and many more titles and awards, among them. As a doctor of traditional medicine, he was named the best folk healer in Russia. It was he who developed many methods and principles of rendering medical care astronauts in flight. It was he who created a unique hospital - a hospital on board a space ship. At the same time he was the state coordinator of the direction of cosmetic medicine. Space and cosmetics. His passion for hydrogen is not aimed at making big money, as is now the case in domestic medicine, but on the contrary, to teach people how to cure anything from literally a penny remedy, without additional visits to pharmacies.

He promotes treatment with a drug that is present in literally every home. This is hydrogen peroxide. You can criticize Neumyvakin as much as you like, he will still insist on his own: yes, indeed, literally everything can be cured with hydrogen peroxide, because it saturates the internal cells of the body with oxygen, destroys toxins, normalizes acid and alkaline balance, and from here tissues are regenerated, the entire body is rejuvenated. organism. No one has yet seen anyone cured with hydrogen peroxide, much less examined, but Neumyvakin claims that using this remedy, you can completely get rid of viral, bacterial and fungal diseases, prevent the development of tumors and atherosclerosis, defeat depression, rejuvenate the body and never get sick SARS and colds.

Panacea

Ivan Pavlovich is sure that with the proper use of this simple drug and with all the simple instructions, you can defeat many diseases, including very serious ones. Their list is huge: from periodontal disease and tonsillitis to myocardial infarctions, strokes and diabetes. Such trifles as sinusitis or osteochondrosis fly away from the first treatment sessions. Even cancerous tumors are frightened and run away from hydrogen peroxide, because the immune system is stimulated, the life of the body and its defenses are activated.

Even children can be treated in this way, except that it is better for pregnant women to refrain from using hydrogen peroxide for the time being. This method is also not recommended for people with transplanted organs due to possible tissue incompatibility. The dosage should be strictly observed: from one drop to ten, adding one every day. Three times a day (thirty drops of a three percent solution of hydrogen peroxide per day, wow!) half an hour before meals. You can enter the solution intravenously and under the supervision of a physician. Sometimes hydrogen peroxide is combined for a more effective effect with other drugs. Inside the solution is used only in diluted form - with clean water.

Outwardly

Compresses and rinses were very popular even before Professor Neumyvakin created his methods. Everyone knows that, like alcohol compresses, hydrogen peroxide cannot be used in its pure form, because tissue burns will result, but warts or fungal infections are lubricated locally and with a strong solution - up to fifteen percent.

With skin rashes, with headaches, procedures are also performed in which hydrogen peroxide is involved. The compress should be done with a cotton cloth soaked in a solution of two teaspoons of three percent hydrogen peroxide and fifty milligrams of pure water. Cover the fabric with foil and wrap with wool or a towel. The duration of the compress is from a quarter of an hour to an hour and a half in the morning and evening until recovery.

Doctors' opinion

Opinions are divided, not everyone admires the properties of hydrogen peroxide, moreover, they not only do not believe them, they laugh at them. Among the doctors there are those who supported Neumyvakin and even picked up the development of his theory, but they are in the minority. Most doctors consider such a treatment plan not only ineffective, but often fatal.

Indeed, there is not yet officially a single proven case when a patient would be cured with hydrogen peroxide. At the same time, there is no information about the deterioration of health in connection with the use of this method. But precious time is lost, and a person who has received one of the serious diseases and completely relied on Neumyvakin's panacea runs the risk of being late for the start of his real traditional treatment.

Hydrogen(lat. hydrogenium), H, a chemical element, the first in order in the periodic system of Mendeleev; atomic mass 1.00797. Under normal conditions, V. is a gas; has no color, smell and taste.

History reference. In the writings of chemists of the 16th and 17th centuries. the release of combustible gas during the action of acids on metals has been repeatedly mentioned. In 1766 G. Cavendish collected and examined the escaping gas, calling it "combustible air". As a supporter of the theory phlogiston, Cavendish believed that this gas is pure phlogiston. In 1783 A. Lavoisier by analyzing and synthesizing water, he proved the complexity of its composition, and in 1787 he defined “combustible air” as a new chemical element (V.) and gave it the modern name hydrog e ne (from the Greek hydor - water and genn ao - I give birth), which means "giving birth to water"; this root is used in the names of V. compounds and processes with its participation (for example, hydrides, hydrogenation). The modern Russian name "V." was proposed by M. F. Solovyov in 1824.

Distribution in nature . V. is widely distributed in nature, its content in earth's crust(lithosphere and hydrosphere) is 1% by mass, and 16% by the number of atoms. V. is part of the most common substance on Earth - water (11.19% of V. by mass), in the composition of the compounds that make up coal, oil, natural gases, clay, as well as animal and plant organisms (i.e., in the composition proteins, nucleic acids, fats, carbohydrates, etc.). V. is extremely rare in the free state; it is found in small quantities in volcanic and other natural gases. Negligible amounts of free V. (0.0001% by number of atoms) are present in the atmosphere. In the near-Earth space, V. in the form of a stream of protons forms an internal (“proton”) Earth's radiation belt. In space, V. is the most common element. As plasma it makes up about half the mass of the Sun and most stars, the main part 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 h 2 , methane ch 4 , ammonia nh 3 , water h 2 o , radicals such as ch, nh, oh, sih, ph, etc. In the form of a stream of protons, V. is part of the corpuscular radiation of the Sun and cosmic rays.

Isotopes, atom and molecule. Ordinary V. consists of a mixture of 2 stable isotopes: light V., or protium (1 h), and heavy V., or deuterium(2 h, or d). In natural compounds of V., 1 atom 2 h accounts for an average of 6,800 atoms 1 h. A radioactive isotope has been artificially obtained - superheavy V., or tritium(3 h, or T), with soft? radiation and half-life t 1/2= 12.262 years. In nature, tritium is formed, for example, from atmospheric nitrogen under the action of cosmic ray neutrons; in the atmosphere it is negligible (4 10 -15% of the total number of atoms of air). An extremely unstable isotope 4 h has been obtained. The mass numbers of isotopes 1 h, 2 h, 3 h and 4 h, respectively 1,2, 3 and 4, indicate that the nucleus of an atom of protium contains only 1 proton, deuterium - 1 proton and 1 neutron, tritium - 1 proton and 2 neutrons, 4 h - 1 proton and 3 neutrons. The large difference in the masses of isotopes of hydrogen causes a more noticeable difference in their physical and chemical properties than in the case of isotopes of other elements.

Atom V. 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. The neutral atom V. can also attach 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 allows you to calculate all possible energy levels of the atom V., and therefore, give a complete interpretation of its atomic spectrum. V. atom is used as a model in quantum mechanical calculations energy levels other, more complex atoms. The V. h 2 molecule 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 a. At high temperatures, molecular V. dissociates into atoms (the degree of dissociation at 2000°C is 0.0013; at 5000°C it is 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 V. in the atomic state lasts only a short time, the atoms recombine into molecules h 2 .

Physical and Chemical properties . V. - the lightest of all known substances (14.4 times lighter than air), density 0.0899 g/l at 0°С and 1 atm. V. boils (liquefies) and melts (solidifies) at -252.6 ° C and -259.1 ° C, respectively (only helium has lower melting and boiling points). The critical temperature of V. is very low (-240 ° C), so its liquefaction is associated with great difficulties; critical pressure 12.8 kgf/cm 2 (12,8 atm), critical density 0.0312 g/cm 3 . Of all gases, V. has the highest thermal conductivity, equal at 0 ° C and 1 atm 0,174 Tue/(m· TO), i.e. 4.16 0 -4 cal/(With· cm· °C). Specific heat B. at 0°C and 1 atmC p 14.208 10 3 j/(kg· TO), i.e. 3.394 cal/(G· °C). V. slightly soluble in water (0.0182 ml/g at 20°С and 1 atm), but good - in many metals (ni, pt, pd, etc.), especially in palladium (850 volumes per 1 volume pd). V.'s solubility in metals is associated with its ability to diffuse through them; diffusion through a carbonaceous alloy (for example, steel) is sometimes accompanied by the destruction of the alloy due to the interaction of steel with carbon (the so-called decarbonization). Liquid water is very light (density at -253 ° C 0.0708 g/cm 3) and fluid (viscosity at - 253 ° C 13.8 spaise).

In most compounds, V. exhibits a valency (more precisely, the oxidation state) +1, like sodium and others. alkali metals; usually he is considered as an analogue of these metals, heading 1 gr. Mendeleev's systems. However, in metal hydrides, the B. ion is negatively charged (oxidation state -1), i.e., the na + h - hydride is built like the na + cl - chloride. This and some other facts (the closeness of the physical properties of V. and halogens, the ability of halogens to replace V. in organic compounds) give reason to attribute V. also to group vii periodic system. Under normal conditions, molecular V. is relatively inactive, combining directly with only the most active of the 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 V.. With oxygen, V. forms water: h 2 + 1/2 o 2 \u003d h 2 o with the release of 285.937 10 3 j/mol, i.e. 68.3174 kcal/mol heat (at 25°С and 1 atm). At ordinary temperatures, the reaction proceeds extremely slowly, above 550 ° C - with an explosion. The explosive limits of a hydrogen-oxygen mixture are (by volume) from 4 to 94% h 2, and a hydrogen-air mixture - from 4 to 74% h 2 (a mixture of 2 volumes of h 2 and 1 volume of O 2 is called explosive gas). V. is used to reduce many metals, as it takes away oxygen from their oxides:

cuo + H 2 \u003d cu + h 2 o,

fe 3 o 4 + 4h 2 = 3fe + 4h 2 o, etc.

V. forms hydrogen halides with halogens, for example:

h 2 + cl 2 = 2hcl.

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. interacts with nitrogen to form ammonia: 3h 2 + n 2 = 2nh 3 only on a catalyst and at elevated temperatures and pressures. When heated, V. reacts vigorously with sulfur: h 2 + s = h 2 s (hydrogen sulfide), much more difficult with selenium and tellurium. V. can react with pure carbon without a catalyst only at high temperatures: 2h 2 + C (amorphous) = ch 4 (methane). V. directly reacts with certain metals (alkali, alkaline earth, etc.), forming hydrides: h 2 + 2li = 2lih. V.'s reactions with carbon monoxide are of great practical importance, in which various organic compounds are formed, depending on the temperature, pressure, and catalyst, for example, hcho, ch 3 oh, and others. Unsaturated hydrocarbons react with V., turning into saturated ones, for example:

c n h 2 n + h 2 = c n h 2 n +2.

The role of V. and its compounds in chemistry is exceptionally great. B. determines the acidic properties of the so-called protic acids. V. tends to form with some elements the so-called hydrogen bond, which has a decisive influence on the properties of many organic and inorganic compounds.

Receipt . The main types of raw materials for the industrial production of V. - natural combustible gases, coke oven gas(cm. coke chemistry) and refinery gases, as well as products of gasification of solid and liquid fuels (mainly coal). V. is also obtained from water electrolysis (in places with cheap electricity). The most important methods of producing water from natural gas are the catalytic interaction of hydrocarbons, mainly methane, with water vapor (conversion): ch 4 + h 2 o \u003d co + 3h 2, and the incomplete oxidation of hydrocarbons with oxygen: ch 4 + 1 / 2 o 2 = co + 2h 2 . The resulting carbon monoxide also undergoes conversion: co + h 2 o = co 2 + h 2. V., produced from natural gas, is the cheapest. A very common method of producing V. from water and steam-air gases obtained by gasification of coal. The process is based on the conversion of carbon monoxide. Water gas contains up to 50% h 2 and 40% co; in steam-air gas, in addition to h 2 and co, there is a significant amount of n 2, which is used together with the resulting V. for the synthesis of nh 3. V. is isolated from coke oven gas and petroleum refining gases by removing the remaining components of the gas mixture, which are liquefied more easily than V. during deep cooling. Water electrolysis lead direct current by passing it through a solution of koh or naoh (acids are not used to avoid corrosion of steel equipment). In laboratories, V. is obtained by electrolysis of water, as well as by the reaction between zinc and hydrochloric acid. However, more often they use ready-made factory V. in cylinders.

Application . V. began to be obtained on an industrial scale at the end of the 18th century. for filling balloons. At present, V. is widely used in the chemical industry, mainly for the production ammonia. A major consumer of alcohol is also the production of methyl and other alcohols, synthetic gasoline (synthine), and other products synthesized from hydrogen and carbon monoxide. V. is used for the hydrogenation of solid and heavy liquid fuels, fats, etc., for the synthesis of hcl, for the hydrotreatment of petroleum products, in welding and cutting metals with an oxygen-hydrogen flame (temperatures up to 2800 ° C) and in atomic hydrogen welding(up to 4000°С). Deuterium and tritium isotopes have found very important applications in nuclear power engineering.

Lit.: Nekrasov B.V., Course of General Chemistry, 14th ed., M., 1962; Remi G., Course of inorganic chemistry, trans. from German, vol. 1, M., 1963; Egorov A.P., Shereshevsky D.I., Shmanenkov I.V., General chemical technology of inorganic substances, 4th ed., M., 1964; General chemical technology. Ed. S. I. Volfkovich, vol. 1, M., 1952; Lebedev V.V., Hydrogen, its production and use, M., 1958; Nalbandyan A. B., Voevodsky V. V., The mechanism of oxidation and combustion of hydrogen, M. - L., 1949; Brief chemical encyclopedia, v. 1, M., 1961, p. 619-24.

Machine without exhaust gases. This is a Mirai made by Toyota. The car runs on hydrogen fuel.

Only heated air and water vapor exit the exhaust pipes. The car of the future is already on the road, although it has problems with refueling.

Although, given the prevalence of hydrogen in the universe, there should not be such a snag.

The world consists of 1 substance by three quarters. So, your serial number element hydrogen justifies. Today, all attention to him.

Properties of hydrogen

Being the first element hydrogen generates the first substance. This is water. Its formula is known to be H 2 O.

On the Greek name Hydrogen is written as hidrogenium, where hidro is water and genium is to generate.

However, the name of the element was given not by the Greeks, but by the French naturalist Laurent Lavoisier. Before him, hydrogen was explored by Henry Quevendish, Nicola Lemery and Theophrastus Paracelsus.

The latter, in fact, left the first mention of the first substance to science. The entry is dated to the 16th century. What conclusions have scientists reached about hydrogen?

Element characteristic- duality. A hydrogen atom has only 1 electron. In a number of reactions, the substance gives it away.

This is the behavior of a typical metal from the first group. However, hydrogen is also capable of completing its shell, not giving up, but accepting 1 electron.

In this case, element 1 behaves like halogens. They are located in the 17th group of the periodic system and are prone to formation.

Which of them contains hydrogen? For example, in hydrosulfide. Its formula: - NaHS.

This compound of the element hydrogen is based on. As can be seen, the hydrogen atoms are displaced from it by sodium only partially.

The presence of just one electron and the ability to donate it turns a hydrogen atom into a proton. The nucleus also has only one particle with a positive charge.

Relative mass proton with an electron is equal to 2-mind. The indicator is 14 times less than that of air. Without an electron, matter is even lighter.

The conclusion that hydrogen is a gas suggests itself. But, the element also has a liquid form. Liquefaction occurs at a temperature of -252.8 degrees Celsius.

Due to their small size chemical element hydrogen has the ability to seep through other substances.

So, if you inflate the air not with helium, or with ordinary air, but with pure element No. 1, it will be blown away in a couple of days.

Gas particles will easily pass into the pores. Hydrogen also passes into some metals, for example, and.

Accumulating in their structure, the substance evaporates with increasing temperature.

Though hydrogen enters in the composition of water, it dissolves poorly. It is not for nothing that in laboratories the element is isolated by displacing moisture. And how do industrialists extract the 1st substance? We will devote the next chapter to this.

Hydrogen production

Hydrogen formula allows you to mine it at least 6 ways. The first is steam reforming of methane and natural gas.

Legroin fractions are taken. Pure hydrogen is extracted from them catalytically. This requires the presence of water vapor.

The second way to extract the 1st substance is gasification. the fuel is heated to 1500 degrees, converting into combustible gases.

This requires an oxidizing agent. Ordinary atmospheric oxygen is sufficient.

The third way to produce hydrogen is the electrolysis of water. Current is passed through it. It helps to highlight the desired element on the electrodes.

You can also use pyrolysis. This is the thermal decomposition of compounds. They force to disintegrate, both organics and inorganic substances, for example, the same water. The process takes place at high temperatures.

The fifth way to produce hydrogen is partial oxidation, and the sixth is biotechnology.

The latter refers to the extraction of gas from water by its biochemical splitting. Special algae help.

A closed photobioreactor is needed, therefore, the 6th method is rarely used. In fact, only the steam reforming method is popular.

It is the cheapest and easiest. However, the presence of a mass of alternatives makes hydrogen a desirable raw material for industry, because there is no dependence on a specific source of the element.

Application of hydrogen

Hydrogen is used for synthesis. This compound is a refrigerant in freezing technology, known as a component of ammonia, used as an acid neutralizer.

Hydrogen is also used for the synthesis of hydrochloric acid. This is the second title.

It is needed, for example, for cleaning metal surfaces, polishing them. V Food Industry hydrochloric - acidity regulator E507.

As food additive hydrogen itself has also been registered. Its name on product packaging is E949.

It is used, in particular, in the production of margarine. The hydrogenation system actually makes margarine.

In fatty out vegetable oils part of the connection is broken. Hydrogen atoms stand up at the breakpoints. This is what transforms the fluid substance into relatively.

Cast hydrogen fuel cell it is used, so far, not so much in, but in missiles.

The first substance burns in oxygen, which gives energy for the movement of spacecraft.

Yes, one of the most powerful Russian missiles Energia runs on hydrogen fuel. The first element in it is liquefied.

The combustion reaction of hydrogen in oxygen is also useful in welding. You can fasten the most refractory materials.

The reaction temperature in its pure form is 3000 degrees Celsius. With the use of special it is possible to reach 4000 degrees.

"Surrender" any, any metal. By the way, metals are also obtained with the help of the 1st element. The reaction is based on the release of valuable substances from their oxides.

The nuclear industry complains isotopes of hydrogen. There are only 3 of them. One of them is tritium. He is radioactive.

There are also non-radioactive protium and deuterium. Although tritium radiates danger, it is found in the natural environment.

The isotope is formed in the upper layers of the atmosphere, which are affected by cosmic rays. This leads to nuclear reactions.

In reactors on the surface of the earth, tritium is the result of neutron irradiation.

Hydrogen price

Most often, industrialists offer gaseous hydrogen, naturally, in a compressed state and in a special container that will not let small atoms of matter through.

The first element is divided into technical and refined, that is, the highest grade. There are even hydrogen brands, for example, "A".

GOST 3022-80 applies to it. This is technical gas. For 40 cubic liters, manufacturers ask for a little less than 1000. For 50 liters they give 1300.

GOST for pure hydrogen - R 51673-2000. The purity of the gas is 9.9999%. The technical element, however, is a little inferior.

Its purity is 9.99%. However, for 40 cubic liters pure substance already give more than 13,000 rubles.

The price tag shows how difficult the final stage of gas purification is given to industrialists. For a 50-liter cylinder, you will have to pay 15,000-16,000 rubles.

liquid hydrogen almost never used. Too costly, the losses are great. Therefore, there are no offers to sell or buy.

Liquefied hydrogen is not only difficult to obtain, but also difficult to store. Temperatures of minus 252 degrees are no joke.

Therefore, no one is going to joke, using effective and easy-to-use gas.

Industrial methods of obtaining simple substances depend on the form in which the corresponding element is in nature, that is, what can be the raw material for its production. So, oxygen, available in a free state, is obtained in a physical way- release from liquid air. Almost all hydrogen is in the form of compounds, so chemical methods are used to obtain it. In particular, decomposition reactions can be used. One of the ways to produce hydrogen is the reaction of decomposition of water by electric current.

The main industrial method for producing hydrogen is the reaction with water of methane, which is part of natural gas. It is carried out at high temperature(it is easy to verify that when methane is passed even through boiling water, no reaction occurs):

CH 4 + 2H 2 0 \u003d CO 2 + 4H 2 - 165 kJ

In the laboratory, to obtain simple substances, not necessarily natural raw materials are used, but those starting materials from which it is easier to isolate the desired substance. For example, in the laboratory, oxygen is not obtained from the air. The same applies to the production of hydrogen. One of the laboratory methods for producing hydrogen, which is sometimes used in industry, is the decomposition of water by electric current.

Hydrogen is usually produced in the laboratory by reacting zinc with hydrochloric acid.

In industry

1.Electrolysis of aqueous solutions of salts:

2NaCl + 2H 2 O → H 2 + 2NaOH + Cl 2

2.Passing water vapor over hot coke at approx. 1000°C:

H 2 O + C ⇄ H 2 + CO

3.From natural gas.

Steam conversion: CH 4 + H 2 O ⇄ CO + 3H 2 (1000 °C) Oxygen catalytic oxidation: 2CH 4 + O 2 ⇄ 2CO + 4H 2

4. Cracking and reforming of hydrocarbons in the process of oil refining.

In the laboratory

1.Action of dilute acids on metals. To carry out such a reaction, zinc and hydrochloric acid are most often used:

Zn + 2HCl → ZnCl 2 + H 2

2.Interaction of calcium with water:

Ca + 2H 2 O → Ca (OH) 2 + H 2

3.Hydrolysis of hydrides:

NaH + H 2 O → NaOH + H 2

4.The action of alkalis on zinc or aluminum:

2Al + 2NaOH + 6H 2 O → 2Na + 3H 2 Zn + 2KOH + 2H 2 O → K 2 + H 2

5.With the help of electrolysis. During the electrolysis of aqueous solutions of alkalis or acids, hydrogen is released at the cathode, for example:

2H 3 O + + 2e - → H 2 + 2H 2 O

  • Bioreactor for hydrogen production

Physical properties

Gaseous hydrogen can exist in two forms (modifications) - in the form of ortho - and para-hydrogen.

In the orthohydrogen molecule (mp −259.10 °C, bp −252.56 °C), the nuclear spins are directed in the same way (parallel), while in parahydrogen (mp −259.32 °C, t bp −252.89 °C) - opposite to each other (anti-parallel).

The allotropic forms of hydrogen can be separated by adsorption on active carbon at liquid nitrogen temperature. At very low temperatures, the equilibrium between orthohydrogen and parahydrogen is almost entirely shifted towards the latter. At 80 K, the aspect ratio is approximately 1:1. Desorbed parahydrogen is converted into orthohydrogen upon heating up to the formation of an equilibrium mixture at room temperature (ortho-para: 75:25). Without a catalyst, the transformation occurs slowly, which makes it possible to study the properties of individual allotropic forms. The hydrogen molecule is diatomic - H₂. Under normal conditions, it is a colorless, odorless and tasteless gas. Hydrogen is the lightest gas, its density is many times less density air. Obviously, the smaller the mass of molecules, the higher their speed at the same temperature. As the lightest, hydrogen molecules move faster than the molecules of any other gas and thus can transfer heat from one body to another faster. It follows that hydrogen has the highest thermal conductivity among gaseous substances. Its thermal conductivity is about seven times higher than that of air.

Chemical properties

Hydrogen molecules H₂ are quite strong, and in order for hydrogen to react, a lot of energy must be expended: H 2 \u003d 2H - 432 kJ Therefore, at ordinary temperatures, hydrogen reacts only with very active metals, for example, with calcium, forming calcium hydride: Ca + H 2 \u003d CaH 2 and with the only non-metal - fluorine, forming hydrogen fluoride: F 2 + H 2 \u003d 2HF With most metals and non-metals, hydrogen reacts at elevated temperatures or under other influences, such as lighting. It can “take away” oxygen from some oxides, for example: CuO + H 2 \u003d Cu + H 2 0 The written equation reflects the reduction reaction. Reduction reactions are called processes, as a result of which oxygen is taken away from the compound; Substances that take away oxygen are called reducing agents (they themselves oxidize). Further, another definition of the concepts of "oxidation" and "reduction" will be given. A this definition, historically the first, retains its importance at the present time, especially in organic chemistry. The reduction reaction is the opposite of the oxidation reaction. Both of these reactions always proceed simultaneously as one process: when one substance is oxidized (reduced), the other is necessarily reduced (oxidized) at the same time.

N 2 + 3H 2 → 2 NH 3

Forms with halogens hydrogen halides:

F 2 + H 2 → 2 HF, the reaction proceeds with an explosion in the dark and at any temperature, Cl 2 + H 2 → 2 HCl, the reaction proceeds with an explosion, only in the light.

It interacts with soot at strong heating:

C + 2H 2 → CH 4

Interaction with alkali and alkaline earth metals

Hydrogen forms with active metals hydrides:

Na + H 2 → 2 NaH Ca + H 2 → CaH 2 Mg + H 2 → MgH 2

hydrides- salty, solid substances, easily hydrolyzed:

CaH 2 + 2H 2 O → Ca(OH) 2 + 2H 2

Interaction with metal oxides (usually d-elements)

Oxides are reduced to metals:

CuO + H 2 → Cu + H 2 O Fe 2 O 3 + 3H 2 → 2 Fe + 3H 2 O WO 3 + 3H 2 → W + 3H 2 O

Hydrogenation of organic compounds

Under the action of hydrogen on unsaturated hydrocarbons in the presence of a nickel catalyst and elevated temperature, the reaction occurs hydrogenation:

CH 2 \u003d CH 2 + H 2 → CH 3 -CH 3

Hydrogen reduces aldehydes to alcohols:

CH 3 CHO + H 2 → C 2 H 5 OH.

Geochemistry of hydrogen

Hydrogen is the main building material of the universe. It is the most common element, and all elements are formed from it as a result of thermonuclear and nuclear reactions.

Free hydrogen H 2 is relatively rare in terrestrial gases, but in the form of water it takes an exceptionally important part in geochemical processes.

Hydrogen can be present in minerals in the form of ammonium ion, hydroxyl ion, and crystalline water.

In the atmosphere, hydrogen is continuously produced as a result of the decomposition of water by solar radiation. It migrates to the upper atmosphere and escapes into space.

Application

  • Hydrogen energy

Atomic hydrogen is used for atomic hydrogen welding.

In the food industry, hydrogen is registered as a food additive. E949 as packing gas.

Features of circulation

Hydrogen, when mixed with air, forms an explosive mixture - the so-called detonating gas. This gas is most explosive when the volume ratio of hydrogen and oxygen is 2:1, or hydrogen and air is approximately 2:5, since air contains approximately 21% oxygen. Hydrogen is also flammable. Liquid hydrogen can cause severe frostbite if it comes into contact with the skin.

Explosive concentrations of hydrogen with oxygen occur from 4% to 96% by volume. When mixed with air from 4% to 75 (74)% by volume.

Use of hydrogen

In the chemical industry, hydrogen is used in the production of ammonia, soap and plastics. In the food industry, margarine is made from liquid vegetable oils using hydrogen. Hydrogen is very light and always rises in the air. Once airships and Balloons filled with hydrogen. But in the 30s. 20th century several terrible disasters when the airships exploded and burned. Nowadays, airships are filled with helium gas. Hydrogen is also used as rocket fuel. Someday, hydrogen may be widely used as a fuel for cars and trucks. Hydrogen engines do not pollute the environment and emit only water vapor (however, the production of hydrogen itself leads to some environmental pollution). Our Sun is mostly made up of hydrogen. Solar heat and light are the result of the release of nuclear energy during the fusion of hydrogen nuclei.

Use of hydrogen as a fuel (economic efficiency)

The most important characteristic of substances used as fuel is their heat of combustion. From the course of general chemistry, it is known that the reaction of the interaction of hydrogen with oxygen occurs with the release of heat. If we take 1 mol H 2 (2 g) and 0.5 mol O 2 (16 g) under standard conditions and excite the reaction, then according to the equation

H 2 + 0.5 O 2 \u003d H 2 O

after completion of the reaction, 1 mol of H 2 O (18 g) is formed with an energy release of 285.8 kJ / mol (for comparison: the heat of combustion of acetylene is 1300 kJ / mol, propane - 2200 kJ / mol). 1 m³ of hydrogen weighs 89.8 g (44.9 mol). Therefore, to obtain 1 m³ of hydrogen, 12832.4 kJ of energy will be spent. Taking into account the fact that 1 kWh = 3600 kJ, we get 3.56 kWh of electricity. Knowing the tariff for 1 kWh of electricity and the cost of 1 m³ of gas, we can conclude that it is advisable to switch to hydrogen fuel.

For example, an experimental 3rd generation Honda FCX model with a 156-liter hydrogen tank (containing 3.12 kg of hydrogen at a pressure of 25 MPa) travels 355 km. Accordingly, 123.8 kWh is obtained from 3.12 kg H2. At 100 km, the energy consumption will be 36.97 kWh. Knowing the cost of electricity, the cost of gas or gasoline, their consumption for a car per 100 km is easy to calculate negative economic effect transition of cars to hydrogen fuel. Let's say (Russia 2008), 10 cents per kWh of electricity leads to the fact that 1 m³ of hydrogen leads to a price of 35.6 cents, and taking into account the efficiency of water decomposition of 40-45 cents, the same amount of kWh from burning gasoline costs 12832.4 kJ/42000 kJ/0.7 kg/l*80 cents/l=34 cents at retail prices, while for hydrogen we calculated the ideal variant, without taking into account transportation, depreciation of equipment, etc. For methane with a combustion energy of about 39 MJ per m³, the result will be two to four times lower due to the difference in price (1m³ for Ukraine costs $179, and for Europe $350). That is, the equivalent amount of methane will cost 10-20 cents.

However, we should not forget that when we burn hydrogen, we get clean water, from which it was extracted. That is, we have a renewable storekeeper energy without harm to the environment, unlike gas or gasoline, which are primary sources of energy.

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