HYDROGEN, H (lat. hydrogenium; a. hydrogen; n. Wasserstoff; f. hydrogene; i. hidrogeno), - chemical element periodic table Mendeleev's elements, which are classified simultaneously into 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. At 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 - 0.174 W/(m.K) at 0°C and 1 MPa, specific heat 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 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 fluxes) and cosmic rays(electron flows).
Production and use of hydrogen
Raw materials for industrial production hydrogen - oil refining gases, gasification products, etc. The main methods of producing hydrogen: 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.
interaction with water forms an alkali; c) passive, inactive; b) when interacting with metals, they form salts; d) typical metals; 2. Metal that can be used to produce hydrogen (by reacting it with water at low temperature): a) Zn; b) Mg; c) Au; d) Hg; e) K; 3. Oxides and hydroxides that are able to react with both acids and alkalis are called: a) amphoteric b) acidic c) basic 4. From left to right in periods, metallic properties: a) increase b) weaken c) remain unchanged 5. By-product element subgroups Group VII: a) chlorine b) phosphorus c) manganese d) francium 6. The charge of the nucleus of an atom is determined: a) by the period number b) by the group number c) by the serial number 7. The structure of the atoms of elements with serial numbers 17 and 35 is the same: a ) total number of electrons; c) quantity electronic levels; d) the number of electrons at the last energy level; b) number of neutrons; 8. Element with electronic formula 1s22s2р63s2p4: a) carbon; b) sulfur; c) chlorine; d) sodium; 9. The carbon atom has the electronic formula: a) 1s22s22р3 b) 1s22s2 c) 1s22s22p2 10. The atom of which element has the following structure of the last energy level…3s23p5: a) phosphorus; b) fluorine; c) chlorine; d) magnesium; 11. The number of unpaired electrons in the electron shell of element No. 19: a) 1; b) 2; at 3; d) 4; 12. Ordinal number of an element whose atoms are capable of forming a higher oxide of the RO3 type: a) No. 11 (sodium); b) No. 14 (silicon); c) No. 16 (sulfur); 13. An element with the electronic formula 1s22s22p63s23p5 forms a volatile hydrogen compound of the type: a) RH4; b) RH3; c) H2R; d) HR; 14. Volume of 3 moles of hydrogen at normal conditions: a) 22.4 l; b) 44.8 l; c) 67.2 l; d) 89.6 l; e) 112 l; 15. Element of the fourth period, located in a secondary subgroup; oxide and hydroxide exhibit amphoteric character. This element forms an oxide of the RO type and a hydroxide R(OH)2. a) magnesium b) calcium c) zinc d) carbon 16. Maximum valence of silicon: a) IV b) V c) VI d) VII 17. Minimum valency of selenium (No. 34): a) I b) II c) III d ) IV 18. Molecular weight of a salt obtained by the interaction of two higher oxides elements with the atomic configuration in them respectively 1s22s22p63s23p64s1 and 1s22s22p3 is equal to: a) 85; b) 111; c) 63; d) 101; e) 164; 19. Product “X”, which is obtained as a result of transformations: Al salt Al(OH)3 X a) Al Cl3 b) Al H3 c) Na Al O2 d) Al e) Al2O3 20. The sum of the coefficients in the reaction equation, the diagram of which H2S + O2 → SO2 + H2O a) 5; b) 6; at 7; d) 8; e) 9; 21. Molar mass magnesium oxide (in g/mol): a) 24; b) 36; c) 40; d) 80; e) 82; 22. The number of moles of iron (III) oxide constituting 800 g of this compound: a) 1; b) 2; at 3; d) 4; e) 5; 23. When 8 g of CH4 methane was burned, 401 kJ of heat was released. Calculate Thermal Effect (Q) chemical reaction CH4 (g) + 2O2 (g) = CO2 (g) + 2H2O (g) + Q: a) + 401 kJ; b) + 802 kJ; c) - 802 kJ; d) + 1604 kJ; e) - 1604 kJ; 24. Under normal conditions, 128 g of oxygen occupy the volume of: a) 11.2 l; b) 22.4 l; c) 44.8 l; d) 67.2 l; e) 89.6 l; 25. Mass fraction hydrogen in the SiH4 compound is: a) 30%; b) 12.5%; c) 40%; d) 60%; e) 65%; 26. The mass fraction of oxygen in the compound EO2 is 50%. Name of element E in the compound: a) nitrogen; b) titanium; c) sulfur; d) selenium; e) carbon; 27. The number of moles of iron (III) oxide interacting with 44.8 liters of hydrogen (n.s.): a) 0.67 mol; b) 2 mol; c) 0.3 mol; d) 0.4 mol; e) 5 mol; 28. Mass of hydrochloric acid required to obtain 44.8 liters of hydrogen (n.s.) (Mg + 2HCl = MgCl2 + H2): a) 146 g; b) 73 g; c) 292 g; d) 219 g; e) 20 g; 29. Mass of salt contained in 400 g of 80% sodium chloride solution: a) 146 g; b) 320 g; c) 210 g; d) 32 g; e) 200 g; 30. The mass of salt that is formed by the interaction of potassium hydroxide with 300 g of a 65% solution of orthophosphoric acid: a) 422 g; b) 196 g; c) 360 g; d) 435 g; e) 200 g;
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 that it can learn more about it as one of the most possible Vehicle in the future. Hydrogen is the simplest, lightest, most common element, there is a lot of it everywhere - seventy-five percent of the total mass of matter. It is present in any star, there is 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 for everyone famous 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 observations, he realized that during the combustion of hydrogen, water is formed. Previously, scientists isolated this element, but did not consider it independent. In 1783, hydrogen received the name hydrogen (translated from the Greek “hydro” - water, and “gen” - to give birth). The element that produces water is hydrogen. This is a gas whose molecular formula is H2. If the temperature is close to room temperature and the pressure is normal, this element is imperceptible. Hydrogen may not even be detected by human senses - it is tasteless, colorless, and 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. Liquid hydrogen is used as rocket fuel.
Hydrogen can become solid, metallic, but this requires ultra-high pressure, and this is exactly what the most prominent scientists - physicists and chemists - are doing now. Already now this element serves as an alternative fuel for transport. Its application is similar to how an engine works internal combustion: When hydrogen is burned, a lot of it is released chemical energy. 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. Perhaps, soon transport will “switch” from gasoline to hydrogen - a lot of automakers are interested in creating alternative combustible materials, and there are successes. But a purely hydrogen engine is still in the future; there are many difficulties here. However, the advantages are such that the creation of a fuel tank with solid hydrogen is underway full swing, and scientists and engineers are not going to retreat.
Basic information
Hydrogenium (lat.) - hydrogen, first serial number in the periodic table, it 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 flammable gas, denoting it differently. But it worked for everyone the same conditions- when the metal is exposed to acid. Hydrogen, even by Cavendish himself, was simply called “flammable air” for many years. Only in 1783 did Lavoisier prove that water has a complex composition through synthesis and analysis, and four years later he gave it to “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 is involved. 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. Water is most abundant on Earth, and 11.19% by mass of it is hydrogen. It is also certainly present in almost all compounds that make up oil, coal, all natural gases, and clay. There is hydrogen in all organisms of plants and animals - in proteins, fats, nucleic acids, carbohydrates and so on. The free state is not typical for hydrogen and almost never occurs - there is very little of it in natural and volcanic gases. A very insignificant amount of hydrogen in the atmosphere is 0.0001%, by the number of atoms. But entire streams of protons represent hydrogen in near-Earth space, which makes up the internal radiation belt of our planet.
Space
No element is as common in space as hydrogen. The volume of hydrogen in the elements of the Sun is more than half of its mass. Most stars produce hydrogen in the form of plasma. The bulk of the various gases of nebulae and the interstellar medium also consists of hydrogen. It is present in comets and in the atmosphere of a number of planets. Naturally, not in pure form, - sometimes as free H 2 , sometimes as methane CH 4 , sometimes as ammonia NH 3 , even like water H 2 O. Radicals CH, NH, SiN, OH, PH and the like are very common. As a stream of protons, hydrogen is part of 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, the hydrogen compound contains isotopes in the following proportions: for one deuterium atom there are 6800 protium atoms. Tritium is formed in the atmosphere from nitrogen, which is affected by neutrons from cosmic rays, but in negligible quantities. What do isotope mass numbers 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 atomic nucleus. Tritium in its nucleus already has two neutrons for every proton. But 4 H contains three neutrons per proton. That's why physical properties and the chemical properties of hydrogen isotopes are very different compared to the isotopes of all other elements - the difference in mass is too large.
Structure and physical properties
The structure of the hydrogen atom is the simplest compared to all other elements: one nucleus - one electron. Ionization potential - the energy of binding a nucleus to an electron - 13.595 electron volts (eV). It is precisely because of the simplicity of this structure that the hydrogen atom is convenient as a model in quantum mechanics when to calculate energy levels more complex atoms. In the H2 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, practically no interaction with hydrogen occurs - 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 balloons flying away at holidays - they have hydrogen inside them). However, it can boil, liquefy, melt, solidify, and only helium boils and melts at lower temperatures. It is difficult to liquefy; you need a temperature below -240 degrees Celsius. But it has very high thermal conductivity. It is almost insoluble in water, but it interacts well with hydrogen of metals - it dissolves in almost all, best of all in palladium (one volume of hydrogen takes eight hundred and fifty volumes). Liquid hydrogen is light and fluid, and when dissolved in metals, it often destroys alloys due to interaction with carbon (steel, for example), diffusion and decarbonization occur.
Chemical properties
In compounds, for the most part, hydrogen shows an oxidation state (valence) of +1, like sodium and other alkali metals. It is considered as their analogue, standing at the head of the first group of the periodic system. But the hydrogen ion in metal hydrides is negatively charged, with an oxidation state of -1. This element is also close to halogens, which are even capable of replacing it in organic compounds. This means that hydrogen can also be attributed to the seventh group of the periodic system. Under normal conditions, hydrogen molecules do not differ in activity, combining only with the most active non-metals: good with fluorine, and if light - with chlorine. But when heated, hydrogen becomes different - it reacts with many elements. Atomic hydrogen, compared to molecular hydrogen, is very chemically active, so water is formed in connection with oxygen, and energy and heat are simultaneously released. At room temperature this reaction is very slow, but when heated above five hundred and fifty degrees, an explosion occurs.
Hydrogen is used to reduce metals because it removes 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 reacts very actively with sulfur, and hydrogen sulfide is obtained. With tellurium and selenium it is difficult to cause a hydrogen reaction, but with pure carbon the reaction occurs at very high temperatures, and methane is obtained. Hydrogen forms various organic compounds with carbon monoxide; pressure, temperature, catalysts influence this, and all this is of great practical importance. And in general, the role of hydrogen, as well as its compounds, is extremely great, since it gives acid properties protic acids. A hydrogen bond is formed with many elements, affecting the properties of both inorganic and organic compounds.
Receipt and use
Hydrogen is produced on an industrial scale from natural gases - combustible gases, coke oven gas, and oil refining gases. It can also be produced by electrolysis where electricity is not too expensive. However in the most important way Hydrogen production is the catalytic interaction of hydrocarbons, mostly methane, with water vapor, when conversion is obtained. The method of oxidizing hydrocarbons with oxygen is also widely used. Hydrogen production 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 remaining components are liquefied. They are more easily liquefied, and for hydrogen, as we remember, you need -252 degrees.
Hydrogen peroxide is very popular in use. 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 received from playing with a kitten most often do not realize that they are using hydrogen treatment. But everyone knows the history: since 1852, hydrogen for a long time used in aeronautics. The airship, invented by Henry Giffard, was created based on hydrogen. They were called zeppelins. Zeppelins were driven out of the skies by the rapid development of aircraft manufacturing. In 1937 there was 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 distribution of balloons filled with hydrogen was widespread. In addition to the production of ammonia, hydrogen is now needed for the production of methyl alcohol and other alcohols, gasoline, hydrogenated heavy fuel oil and solid fuel. You cannot do without hydrogen when welding, when cutting metals - it can be oxygen-hydrogen and atomic-hydrogen. And tritium and deuterium give life to nuclear energy. These, as we remember, are isotopes of hydrogen.
Neumyvakin
Hydrogen is such a good chemical element that it has its own fans. Ivan Pavlovich Neumyvakin is a doctor of medical sciences, professor, laureate of the State Prize, and he has many more titles and awards, among them. Being a doctor of traditional medicine, he is named the best folk healer in Russia. It was he who developed many methods and principles of providing medical care to astronauts in flight. It was he who created a unique hospital - a hospital on board a spaceship. At the same time, he was the state coordinator for 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, at teaching people how to cure anything literally with a penny remedy, without an additional visit to a pharmacy.
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 them, but Neumyvakin claims that by 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 ARVI and colds.
Panacea
Ivan Pavlovich is confident that with proper use of this simple drug and following all the simple instructions, you can overcome many diseases, including very serious ones. The list is huge: from periodontal disease and tonsillitis to myocardial infarction, strokes and diabetes. Such trifles as sinusitis or osteochondrosis disappear from the first treatment sessions. Even cancerous tumors they get scared and run away from hydrogen peroxide because the immune system is stimulated, the life of the body and its defense are activated.
Even children can be treated in this way, except that it is better for pregnant women to refrain from consuming hydrogen peroxide for now. Also not recommended this method people with transplanted organs due to possible tissue incompatibility. The dosage must 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. The solution can be administered intravenously and under medical supervision. Sometimes hydrogen peroxide is combined with other drugs for a more effective effect. The solution is used internally only in diluted form - with clean water.
Externally
Even before Professor Neumyvakin created his method, compresses and rinses were very popular. Everyone knows that, just like alcohol compresses, hydrogen peroxide cannot be used in its pure form, because it will cause tissue burns, but warts or fungal infections are lubricated locally with a strong solution - up to fifteen percent.
For skin rashes and headaches, procedures are also done that involve hydrogen peroxide. The compress should be made using a cotton cloth soaked in a solution of two teaspoons of three percent hydrogen peroxide and fifty milligrams of clean water. Cover the fabric with film and wrap it with wool or a towel. The compress lasts 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 is delighted with the properties of hydrogen peroxide; moreover, they not only do not believe them, they laugh at them. Among the doctors there are also those who supported Neumyvakin and even took up the development of his theory, but they are a minority. Most of Doctors consider this type of treatment not only ineffective, but also often disastrous.
Indeed, there is not yet a single officially proven case in which a patient was 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 the person who received one of serious illnesses and completely relying on Neumyvakin’s panacea risks being late for the start of his real traditional treatment.
Liquid
Hydrogen(lat. Hydrogenium; indicated by the symbol H) is the first element of the periodic table of elements. Widely distributed in nature. The cation (and nucleus) of the most common isotope of hydrogen, 1 H, is the proton. The properties of the 1 H nucleus make it possible to widely use NMR spectroscopy in the analysis of organic substances.
Three isotopes of hydrogen have their own names: 1 H - protium (H), 2 H - deuterium (D) and 3 H - tritium (radioactive) (T).
Simple substance hydrogen - H 2 - light colorless gas. When mixed with air or oxygen, it is flammable and explosive. Non-toxic. Soluble in ethanol and a number of metals: iron, nickel, palladium, platinum.
Story
The release of flammable gas during the interaction of acids and metals was observed in the 16th and XVII centuries at the dawn of the formation of chemistry as a science. Mikhail Vasilyevich Lomonosov also directly pointed out its isolation, but he was already definitely aware that it was not phlogiston. The English physicist and chemist Henry Cavendish examined this gas in 1766 and called it “combustible air.” When burned, the “combustible air” produced water, but Cavendish’s adherence to the phlogiston theory prevented him from drawing the correct conclusions. The French chemist Antoine Lavoisier, together with the engineer J. Meunier, using special gasometers, in 1783 carried out the synthesis of water, and then its analysis, decomposing water vapor with hot iron. Thus, he established that “combustible air” is part of water and can be obtained from it.
origin of name
Lavoisier gave hydrogen the name hydrogène - “giving birth to water.” The Russian name “hydrogen” was proposed by the chemist M. F. Soloviev in 1824 - by analogy with Slomonosov’s “oxygen”.
Prevalence
Hydrogen is the most abundant element in the Universe. It accounts for about 92% of all atoms (8% are helium atoms, the share of all other elements combined is less than 0.1%). Thus, hydrogen is the main component of stars and interstellar gas. Under conditions of stellar temperatures (for example, the surface temperature of the Sun is ~ 6000 °C), hydrogen exists in the form of plasma, in interstellar space this element exists in the form of individual molecules, atoms and ions and can form molecular clouds that vary significantly in size, density and temperature.
Earth's crust and living organisms
The mass fraction of hydrogen in the earth's crust is 1% - it is the tenth most abundant element. However, its role in nature is determined not by mass, but by the number of atoms, the share of which among other elements is 17% (second place after oxygen, the share of atoms of which is ~ 52%). Therefore, the value of hydrogen in chemical processes occurring on Earth is almost as great as oxygen. Unlike oxygen, which exists on Earth in both bound and free states, almost all hydrogen on Earth is in the form of compounds; Only a very small amount of hydrogen in the form of a simple substance is contained in the atmosphere (0.00005% by volume).
Hydrogen is part of almost all organic substances and is present in all living cells. In living cells, hydrogen accounts for almost 50% of the number of atoms.
Receipt
Industrial methods for producing simple substances depend on the form in which the corresponding element is found in nature, that is, what can be the raw material for its production. Thus, oxygen, which is available in a free state, is obtained physically - by separation from liquid air. Almost all of hydrogen is in the form of compounds, so to obtain it they use chemical methods. In particular, decomposition reactions can be used. One way to produce hydrogen is through the decomposition of water by electric current.
The main industrial method for producing hydrogen is the reaction of methane, which is part of natural gas, with water. It is carried out at high temperature(it’s easy to see that when passing methane even through boiling water, no reaction occurs):
CH 4 + 2H 2 O = CO 2 + 4H 2 −165 kJ
In the laboratory, to obtain simple substances, they do not necessarily use natural raw materials, but choose those starting materials from which it is easier to isolate the required 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.
Typically, hydrogen is produced in the laboratory by reacting zinc with hydrochloric acid.
In industry
1.Electrolysis of aqueous salt solutions:
2NaCl + 2H 2 O → H 2 + 2NaOH + Cl 2
2.Passing water vapor over hot coke at a temperature of about 1000 °C:
H2O+C? H2+CO
3. From natural gas.
Steam conversion:
CH 4 + H 2 O ? CO + 3H 2 (1000 °C)
Catalytic oxidation with oxygen:
2CH 4 + O 2 ? 2CO + 4H2
4. Cracking and reforming of hydrocarbons during oil refining.
In the laboratory
1.The effect of dilute acids on metals. To carry out this reaction, zinc and dilute 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.Effect of alkalis on zinc or aluminum:
2Al + 2NaOH + 6H 2 O → 2Na + 3H 2
Zn + 2KOH + 2H 2 O → K 2 + H 2
5.Using 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
Physical properties
Hydrogen can exist in two forms (modifications) - in the form of ortho- and para-hydrogen. In an orthohydrogen molecule o-H 2 (mp −259.10 °C, bp −252.56 °C) nuclear spins are directed identically (parallel), and for parahydrogen p-H 2 (melting point −259.32 °C, boiling point −252.89 °C) - opposite to each other (antiparallel). Equilibrium mixture o-H 2 and p-H 2 at a given temperature is called equilibrium hydrogen e-H2.
Hydrogen modifications can be separated by adsorption on active carbon at a temperature liquid nitrogen. At very low temperatures, the equilibrium between orthohydrogen and parahydrogen is almost completely shifted towards the latter. At 80 K the ratio of forms is approximately 1:1. When heated, desorbed parahydrogen is converted into orthohydrogen until a mixture is formed that is equilibrium at room temperature (ortho-para: 75:25). Without a catalyst, the transformation occurs slowly (under conditions of the interstellar medium - with characteristic times up to cosmological ones), which makes it possible to study the properties of individual modifications.
Hydrogen is the lightest gas, it is 14.5 times lighter than air. Obviously, the smaller the mass of the molecules, the higher their speed at the same temperature. As the lightest molecules, 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 approximately seven times higher than the thermal conductivity of air.
The hydrogen molecule is diatomic - H2. Under normal conditions, it is a colorless, odorless, and tasteless gas. Density 0.08987 g/l (no.), boiling point −252.76 °C, specific heat combustion 120.9×10 6 J/kg, slightly soluble in water - 18.8 ml/l. Hydrogen is highly soluble in many metals (Ni, Pt, Pd, etc.), especially in palladium (850 volumes per 1 volume of Pd). The solubility of hydrogen 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 hydrogen with carbon (so-called decarbonization). Practically insoluble in silver.
Liquid hydrogen exists in a very narrow temperature range from −252.76 to −259.2 °C. It is a colorless liquid, very light (density at −253 °C 0.0708 g/cm3) and fluid (viscosity at −253 °C 13.8 spuaz). The critical parameters of hydrogen are very low: temperature −240.2 °C and pressure 12.8 atm. This explains the difficulties in liquefying hydrogen. In the liquid state, equilibrium hydrogen consists of 99.79% para-H2, 0.21% ortho-H2.
Solid hydrogen, melting point −259.2 °C, density 0.0807 g/cm 3 (at −262 °C) - snow-like mass, hexagonal crystals, space group P6/mmc, cell parameters a=3,75 c=6.12. At high pressure, hydrogen transforms into a metallic state.
Isotopes
Hydrogen occurs in the form of three isotopes that have individual names: 1 H - protium (H), 2 H - deuterium (D), 3 H - tritium (radioactive) (T).
Protium and deuterium are stable isotopes with mass numbers 1 and 2. Their content in nature is 99.9885 ± 0.0070% and 0.0115 ± 0.0070%, respectively. This ratio may vary slightly depending on the source and method of producing hydrogen.
The hydrogen isotope 3H (tritium) is unstable. Its half-life is 12.32 years. Tritium occurs naturally in very small quantities.
The literature also provides data on hydrogen isotopes with mass numbers of 4 - 7 and half-lives of 10 -22 - 10 -23 s.
Natural hydrogen consists of H 2 and HD (deuterium hydrogen) molecules in a ratio of 3200:1. The content of pure deuterium hydrogen D 2 is even less. The ratio of the concentrations of HD and D 2 is approximately 6400:1.
Of all isotopes chemical elements physical and Chemical properties Hydrogen isotopes differ most strongly from each other. This is due to the largest relative change in atomic masses.
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Deuterium and tritium also have ortho- and para-modifications: p-D 2 , o-D 2 , p-T 2, o-T 2 . Heteroisotope hydrogen (HD, HT, DT) does not have ortho- and para-modifications.
Chemical properties
Fraction of dissociated hydrogen molecules
Hydrogen molecules H2 are quite strong, and in order for hydrogen to react, a lot of energy must be expended:
H 2 = 2H − 432 kJ
Therefore, at ordinary temperatures, hydrogen reacts only with very active metals, such as calcium, forming calcium hydride:
Ca + H 2 = CaH 2
and with the only non-metal - fluorine, forming hydrogen fluoride:
Hydrogen reacts with most metals and non-metals at elevated temperatures or under other influences, for example, lighting:
O 2 + 2H 2 = 2H 2 O
It can “take away” oxygen from some oxides, for example:
CuO + H 2 = Cu + H 2 O
The written equation reflects restorative properties hydrogen.
N 2 + 3H 2 → 2NH 3
Forms hydrogen halides with halogens:
F 2 + H 2 → 2HF, the reaction occurs explosively in the dark and at any temperature,
Cl 2 + H 2 → 2HCl, the reaction proceeds explosively, only in the light.
It interacts with soot under high heat:
C + 2H 2 → CH 4
Interaction with alkali and alkaline earth metals
When interacting with active metals, hydrogen forms hydrides:
2Na + H 2 → 2NaH
Ca + H 2 → CaH 2
Mg + H 2 → MgH 2
Hydrides- salt-like, 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 → 2Fe + 3H 2 O
WO 3 + 3H 2 → W + 3H 2 O
Hydrogenation of organic compounds
Molecular hydrogen is widely used in organic synthesis for the recovery of organic compounds. These processes are called hydrogenation reactions. These reactions are carried out in the presence of a catalyst at elevated pressure and temperature. The catalyst can be either homogeneous (eg Wilkinson Catalyst) or heterogeneous (eg Raney nickel, palladium on carbon).
Thus, in particular, during the catalytic hydrogenation of unsaturated compounds such as alkenes and alkynes, saturated compounds are formed - alkanes.
Geochemistry of hydrogen
Free hydrogen H2 is relatively rare in terrestrial gases, but in the form of water it takes an extremely 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. Having a low mass, hydrogen molecules have a high speed of diffusion movement (it is close to the second escape velocity) and, falling into the upper layers of the atmosphere, can fly into outer space.
Features of treatment
Hydrogen, when mixed with air, forms an explosive mixture - the so-called detonating gas. This gas is most explosive when volumetric ratio hydrogen and oxygen 2:1, or hydrogen and air approximately 2:5, since air contains approximately 21% oxygen. Hydrogen is also a fire hazard. Liquid hydrogen can cause severe frostbite if it comes into contact with the skin.
Explosive concentrations of hydrogen and oxygen occur from 4% to 96% by volume. When mixed with air from 4% to 75(74)% by volume.
Economy
The cost of hydrogen for large wholesale supplies ranges from $2-5 per kg.
Application
Atomic hydrogen is used for atomic hydrogen welding.
Chemical industry
- In the production of ammonia, methanol, soap and plastics
- In the production of margarine from liquid vegetable oils
- Registered as a dietary supplement E949(packing gas)
Food industry
Aviation industry
Hydrogen is very light and always rises in the air. Once upon a time, airships and balloons were filled with hydrogen. But in the 30s. XX century There were several disasters during which airships exploded and burned. Nowadays, airships are filled with helium, despite its significantly higher cost.
Fuel
Hydrogen is used as rocket fuel.
Research is underway on the use of hydrogen as a fuel for cars and trucks. Hydrogen engines do not pollute environment and only release water vapor.
Hydrogen-oxygen fuel cells use hydrogen to directly convert the energy of a chemical reaction into electrical energy.
"Liquid Hydrogen"(“LH”) is the liquid state of hydrogen, with a low specific density of 0.07 g/cm³ and cryogenic properties with a freezing point of 14.01 K (−259.14 °C) and a boiling point of 20.28 K (−252.87 °C). It is a colorless, odorless liquid which, when mixed with air, is classified as explosive substances with a flammability coefficient range of 4-75%. The spin ratio of isomers in liquid hydrogen is: 99.79% - parahydrogen; 0.21% - orthohydrogen. Hydrogen expansion coefficient when changing state of aggregation to gaseous is 848:1 at 20°C.
As with any other gas, liquefaction of hydrogen leads to a decrease in its volume. After liquefaction, liquid liquid is stored in thermally insulated containers under pressure. Liquid hydrogen Liquid hydrogen, LH2, LH 2) is actively used in industry, as a form of gas storage, and in the space industry, as rocket fuel.
Story
The first documented use of artificial refrigeration was carried out by the English scientist William Cullen in 1756, Gaspard Monge was the first to obtain a liquid state of sulfur oxide in 1784, Michael Faraday was the first to obtain liquefied ammonia, the American inventor Oliver Evans was the first to develop a refrigeration compressor in 1805, Jacob Perkins was the first to patent cooling machine in 1834 and John Gorey was the first to patent an air conditioner in the United States in 1851. Werner Siemens proposed the concept of regenerative cooling in 1857, Karl Linde patented equipment for producing liquid air using a cascade "Joule-Thomson expansion effect" and regenerative cooling in 1876. In 1885, the Polish physicist and chemist Zygmunt Wroblewski published critical temperature hydrogen 33 K, critical pressure 13.3 atm. and boiling point at 23 K. Hydrogen was first liquefied by James Dewar in 1898 using regenerative cooling and his invention, the Dewar flask. The first synthesis of a stable isomer of liquid hydrogen, parahydrogen, was carried out by Paul Harteck and Carl Bonhoeffer in 1929.
Spin isomers of hydrogen
Hydrogen at room temperature consists primarily of a spin isomer, orthohydrogen. After production, liquid hydrogen is in a metastable state and must be converted to the parahydrogen form in order to avoid the explosive exothermic reaction that occurs when it changes at low temperatures. Conversion to the parahydrogen phase is usually done using catalysts such as iron oxide, chromium oxide, Activated carbon, platinum-coated asbestos, rare earth metals or by using uranium or nickel additives.
Usage
Liquid hydrogen can be used as a form of fuel storage for internal combustion engines and fuel cells. Various submarines (projects "212A" and "214", Germany) and hydrogen transport concepts have been created using this aggregate form of hydrogen (see for example "DeepC" or "BMW H2R"). Due to the proximity of the designs, the creators of LHV equipment can use or only modify systems using liquefied natural gas (LNG). However, due to the lower volumetric energy density, combustion requires a larger volume of hydrogen than natural gas. If liquid hydrogen is used instead of "CNG" in piston engines, a more bulky fuel system is usually required. With direct injection, increased losses in the intake tract reduce cylinder filling.
Liquid hydrogen is also used to cool neutrons in neutron scattering experiments. The masses of the neutron and the hydrogen nucleus are practically equal, so the exchange of energy at elastic collision most effective.
Advantages
The advantage of using hydrogen is the “zero emissions” of its use. The product of its interaction with air is water.
Obstacles
One liter of “ZhV” weighs only 0.07 kg. That is, its specific gravity is 70.99 g/l at 20 K. Liquid hydrogen requires cryogenic storage technology, such as special thermally insulated containers and requires special handling, which is typical for all cryogenic materials. In this respect he is close to liquid oxygen, but requires greater caution due to fire hazard. Even with insulated containers, it is difficult to keep it at the low temperatures required to keep it liquid (it typically evaporates at a rate of 1% per day). When handling it, you also need to follow the usual safety precautions when working with hydrogen - it is cold enough to liquefy air, which is explosive.
Rocket fuel
Liquid hydrogen is a common component of rocket fuels, which is used for jet acceleration of launch vehicles and spacecraft. In most liquid hydrogen rocket engines, it is first used to regeneratively cool the nozzle and other engine parts before it is mixed with an oxidizer and burned to produce thrust. Modern engines using H 2 /O 2 components consume a fuel mixture over-enriched in hydrogen, which leads to a certain amount of unburned hydrogen in the exhaust. In addition to increasing the specific impulse of the engine by reducing molecular weight, this also reduces erosion of the nozzle and combustion chamber.
Such obstacles to the use of LH in other areas, such as cryogenic nature and low density, are also a limiting factor for use in this case. As of 2009, there is only one launch vehicle (Delta-4 launch vehicle), which is entirely a hydrogen rocket. Basically, “ZhV” is used either on the upper stages of rockets or on blocks, which perform a significant part of the work of launching the payload into space in a vacuum. As one of the measures to increase the density of this type of fuel, there are proposals to use sludge-like hydrogen, that is, a semi-frozen form of “liquid hydrogen”.
Hydrogen
HYDROGEN-A; m. Chemical element (H), a light, colorless and odorless gas that combines with oxygen to form water.
◁ Hydrogen, oh, oh. Second connections. B bacteria. 2nd bomb(huge bomb destructive force, the explosive action of which is based on thermonuclear reaction). Hydrogenous, oh, oh.
hydrogen(lat. Hydrogenium), a chemical element of group VII of the periodic system. There are two stable isotopes found in nature (protium and deuterium) and one radioactive one (tritium). The molecule is diatomic (H 2). Colorless and odorless gas; density 0.0899 g/l, t kip - 252.76°C. Combines with many elements and forms water with oxygen. The most common element of the cosmos; makes up (in the form of plasma) more than 70% of the mass of the Sun and stars, the main part of the gases of the interstellar medium and nebulae. The hydrogen atom is part of many acids and bases, and most organic compounds. They are used in the production of ammonia, hydrochloric acid, for the hydrogenation of fats, etc., in welding and cutting metals. Promising as a fuel (see Hydrogen energy).
HYDROGENHYDROGEN (lat. Hydrogenium), H, chemical element with atomic number 1, atomic mass 1.00794. The chemical symbol for hydrogen, H, is read in our country as “ache,” as this letter is pronounced in French.
Natural hydrogen consists of a mixture of two stable nuclides (cm. NUCLIDE) with mass numbers 1.007825 (99.985% in the mixture) and 2.0140 (0.015%). In addition, natural hydrogen always contains minute amounts of the radioactive nuclide - tritium (cm. TRITIUM) 3 N (half-life T 1/2 12.43 years). Since the nucleus of a hydrogen atom contains only 1 proton (there cannot be fewer protons in the nucleus of an atom of an element), it is sometimes said that hydrogen forms a natural lower limit D.I. Mendeleev’s periodic table of elements (although the element hydrogen itself is located at the very top of the table). The element hydrogen is located in the first period of the periodic table. It is also included in group 1 (group IA alkali metals (cm. ALKALI METALS)), and to group 7 (group VIIA halogens (cm. HALOGEN)).
The atomic masses of hydrogen isotopes differ greatly (by several times). This leads to noticeable differences in their behavior in physical processes(distillation, electrolysis, etc.) and to certain chemical differences (differences in the behavior of isotopes of one element are called isotope effects; for hydrogen, isotope effects are the most significant). Therefore, unlike the isotopes of all other elements, hydrogen isotopes have special symbols and names. Hydrogen with a mass number of 1 is called light hydrogen, or protium (Latin Protium, from the Greek protos - first), denoted by the symbol H, and its nucleus is called a proton (cm. PROTON (elementary particle)), symbol p. Hydrogen with mass number 2 is called heavy hydrogen, deuterium (cm. DEUTERIUM)(Latin Deuterium, from the Greek deuteros - second), the symbols 2 H, or D (read “de”) are used to designate it, the nucleus d is deuteron. Radioactive isotope with mass number 3 is called superheavy hydrogen, or tritium (Latin Tritum, from Greek tritos - third), symbol 2 H or T (read “those”), nucleus t - triton.
Configuration of the single electron layer of a neutral unexcited hydrogen atom 1 s 1
. In compounds it exhibits oxidation states +1 and, less commonly, –1 (valency I). The radius of a neutral hydrogen atom is 0.024 nm. The ionization energy of the atom is 13.595 eV, the electron affinity is 0.75 eV. According to the Pauling scale, the electronegativity of hydrogen is 2.20. Hydrogen is a non-metal.
In its free form, it is a light flammable gas without color, odor or taste.
History of discovery
The release of flammable gas during the interaction of acids and metals was observed in the 16th and 17th centuries at the dawn of the formation of chemistry as a science. The famous English physicist and chemist G. Cavendish (cm. CAVENDISH Henry) in 1766 he investigated this gas and called it “flammable air.” When burned, "flammable air" produced water, but Cavendish's adherence to the phlogiston theory (cm. PHLOGISTON) prevented him from drawing the right conclusions. French chemist A. Lavoisier (cm. LAVOISIER Antoine Laurent) together with engineer J. Meunier (cm. MENIER Jean Baptiste Marie Charles), using special gasometers, in 1783 he carried out the synthesis of water, and then its analysis, decomposing water vapor with hot iron. Thus, he established that “combustible air” is part of water and can be obtained from it. In 1787, Lavoisier came to the conclusion that “combustible air” is a simple substance, and therefore belongs to the chemical elements. He gave it the name hydrogene (from the Greek hydor - water and gennao - I give birth) - “giving birth to water”. The establishment of the composition of water put an end to the “phlogiston theory.” The Russian name “hydrogen” was proposed by the chemist M. F. Solovyov (cm. SOLOVIEV Mikhail Fedorovich) in 1824. At the turn of the 18th and 19th centuries, it was established that the hydrogen atom is very light (compared to the atoms of other elements), and the weight (mass) of the hydrogen atom was taken as a unit of comparison for the atomic masses of elements. The mass of the hydrogen atom was assigned a value of 1.
Being in nature
Hydrogen accounts for about 1% of the mass of the earth's crust (10th place among all elements). Hydrogen is practically never found in its free form on our planet (its traces are found in upper layers atmosphere), but is distributed almost everywhere on Earth in water. The element hydrogen is found in organic and inorganic compounds living organisms, natural gas, oil, coal. It is, of course, contained in water (about 11% by weight), in various natural crystalline hydrates and minerals, which contain one or more OH hydroxyl groups.
Hydrogen as an element dominates the Universe. It accounts for about half the mass of the Sun and other stars, and is present in the atmosphere of a number of planets.
Receipt
Hydrogen can be produced in many ways. In industry, natural gases are used for this, as well as gases obtained from oil refining, coking and gasification of coal and other fuels. When producing hydrogen from natural gas (the main component is methane), it undergoes catalytic interaction with water vapor and incomplete oxidation with oxygen:
CH 4 + H 2 O = CO + 3H 2 and CH 4 + 1/2 O 2 = CO 2 + 2H 2
The separation of hydrogen from coke oven gas and oil refining gases is based on their liquefaction during deep cooling and the removal from the mixture of gases that liquefy more easily than hydrogen. When cheap electricity is available, hydrogen is produced by electrolysis of water by passing current through alkali solutions. IN laboratory conditions Hydrogen is easily obtained by reacting metals with acids, for example, zinc with hydrochloric acid.
Physical and chemical properties
Under normal conditions, hydrogen is a light (density under normal conditions 0.0899 kg/m3) colorless gas. Melting point –259.15 °C, boiling point –252.7 °C. Liquid hydrogen (at boiling point) has a density of 70.8 kg/m3 and is the most light liquid. Standard electrode potential H 2 /H - in an aqueous solution is taken equal to 0. Hydrogen is poorly soluble in water: at 0 °C the solubility is less than 0.02 cm 3 / ml, but it is well soluble in some metals (sponge iron and others), especially well in metal palladium (about 850 volumes of hydrogen in 1 volume of metal). The heat of combustion of hydrogen is 143.06 MJ/kg.
Exists in the form of diatomic H 2 molecules. The dissociation constant of H 2 into atoms at 300 K is 2.56·10 -34. The energy of dissociation of the H 2 molecule into atoms is 436 kJ/mol. The internuclear distance in the H 2 molecule is 0.07414 nm.
Since the nucleus of each H atom that is part of the molecule has its own spin (cm. SPIN), then molecular hydrogen can be in two forms: in the form of orthohydrogen (o-H 2) (both spins have the same orientation) and in the form of parahydrogen (n-H 2) (spins have different orientations). Under normal conditions, normal hydrogen is a mixture of 75% o-H 2 and 25% p-H 2. The physical properties of p- and o-H 2 differ slightly from each other. So, if the boiling temperature pure o-N 2 20.45 K, then pure p-N 2 - 20.26 K. Transformation o-H 2 in p-H 2 is accompanied by the release of 1418 J/mol of heat.
The scientific literature has repeatedly suggested that when high pressures(above 10 GPa) and at low temperatures (about 10 K and below) solid hydrogen, usually crystallizing in a hexagonal lattice molecular type, can transform into a substance with metallic properties, perhaps even a superconductor. However, so far there is no clear data on the possibility of such a transition.
High strength chemical bond between atoms in the H2 molecule (which, for example, using the molecular orbital method, can be explained by the fact that in this molecule the electron pair is located in the bonding orbital, and the antibonding orbital is not occupied by electrons) leads to the fact that at room temperature hydrogen gas chemically inactive. So, without heating, with simple mixing, hydrogen reacts (explosively) only with fluorine gas:
H 2 + F 2 = 2HF + Q.
If a mixture of hydrogen and chlorine at room temperature is irradiated with ultraviolet light, then the immediate formation of hydrogen chloride HCl is observed. The reaction of hydrogen with oxygen occurs explosively if a catalyst, metal palladium (or platinum), is added to the mixture of these gases. When ignited, a mixture of hydrogen and oxygen (the so-called detonating gas (cm. EXPLOSIVE GAS)) explodes, and an explosion can occur in mixtures in which the hydrogen content ranges from 5 to 95 percent by volume. Pure hydrogen in air or in pure oxygen burns quietly, releasing large quantity heat:
H 2 + 1/2O 2 = H 2 O + 285.75 kJ/mol
If hydrogen interacts with other non-metals and metals, it is only under certain conditions (heating, high pressure, presence of a catalyst). Thus, hydrogen reacts reversibly with nitrogen at elevated pressure (20-30 MPa or more) and at a temperature of 300-400 °C in the presence of a catalyst - iron:
3H 2 + N 2 = 2NH 3 + Q.
Also, only when heated, hydrogen reacts with sulfur to form hydrogen sulfide H 2 S, with bromine to form hydrogen bromide HBr, with iodine to form hydrogen iodide HI. Hydrogen reacts with coal (graphite) to form a mixture of hydrocarbons of various compositions. Hydrogen does not directly interact with boron, silicon, and phosphorus; compounds of these elements with hydrogen are obtained indirectly.
When heated, hydrogen is capable of reacting with alkaline, alkaline earth metals and magnesium with the formation of compounds with an ionic bond nature, which contain hydrogen in the oxidation state –1. Thus, when calcium is heated in a hydrogen atmosphere, a salt-like hydride with the composition CaH 2 is formed. Polymer aluminum hydride (AlH 3) x is one of the most strong reducing agents- obtained indirectly (for example, using organoaluminum compounds). With many transition metals (for example, zirconium, hafnium, etc.), hydrogen forms compounds of variable composition (solid solutions).
Hydrogen is capable of reacting not only with many simple elements, but also with complex substances. First of all, it is necessary to note the ability of hydrogen to reduce many metals from their oxides (such as iron, nickel, lead, tungsten, copper, etc.). Thus, when heated to a temperature of 400-450 °C and above, iron is reduced by hydrogen from any of its oxides, for example:
Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O.
It should be noted that only metals located in the series of standard potentials behind manganese can be reduced from oxides with hydrogen. More active metals (including manganese) are not reduced to metal from oxides.
Hydrogen is capable of adding a double or triple bond to many organic compounds (these are so-called hydrogenation reactions). For example, in the presence of a nickel catalyst, it is possible to carry out the hydrogenation of ethylene C 2 H 4, and ethane C 2 H 6 is formed:
C 2 H 4 + H 2 = C 2 H 6.
Methanol is produced industrially by the reaction of carbon monoxide (II) and hydrogen:
2H 2 + CO = CH 3 OH.
In compounds in which a hydrogen atom is connected to an atom of a more electronegative element E (E = F, Cl, O, N), hydrogen bonds are formed between the molecules (cm. HYDROGEN BONDING)(two E atoms of the same or two different elements are connected to each other through the atom H: E"... N... E"", and all three atoms are located on the same straight line). Such bonds exist between the molecules of water, ammonia, methanol, etc. and lead to a noticeable increase in boiling temperatures these substances, an increase in the heat of evaporation, etc.
Application
Hydrogen is used in the synthesis of ammonia NH 3, hydrogen chloride HCl, methanol CH 3 OH, during hydrocracking (cracking in a hydrogen atmosphere) of natural hydrocarbons, as a reducing agent in the production of certain metals. Hydrogenation (cm. HYDROGENATION) Natural vegetable oils are used to obtain solid fat - margarine. Liquid hydrogen is used as rocket fuel and also as a coolant. A mixture of oxygen and hydrogen is used in welding.
At one time it was suggested that in the near future the main source of energy would be the combustion reaction of hydrogen, and hydrogen energy would replace traditional sources obtaining energy (coal, oil, etc.). It was assumed that in order to obtain hydrogen in on a large scale It will be possible to use electrolysis of water. Electrolysis of water is a rather energy-intensive process, and currently it is unprofitable to produce hydrogen by electrolysis on an industrial scale. But it was expected that electrolysis would be based on the use of medium-temperature (500-600 °C) heat, which large quantities occurs during work nuclear power plants. This heat has limited use, and the possibility of producing hydrogen with its help would solve both the environmental problem (when hydrogen is burned in air, the amount of environmentally harmful substances produced is minimal) and the problem of utilizing medium-temperature heat. However, after Chernobyl disaster The development of nuclear energy is being curtailed everywhere, so that this source of energy becomes unavailable. Therefore the prospects widespread use Hydrogen as an energy source is still shifting until at least the middle of the 21st century.
Features of treatment
Hydrogen is not toxic, but when handling it, one must constantly take into account its high fire and explosion hazard, and the explosion hazard of hydrogen is increased due to high ability gas to diffusion even through some solid materials. Before starting any heating operations in a hydrogen atmosphere, you should make sure that it is clean (when igniting hydrogen in a test tube turned upside down, the sound should be dull, not barking).
Biological role
The biological significance of hydrogen is determined by the fact that it is part of water molecules and all the most important groups of natural compounds, including proteins, nucleic acids, lipids, and carbohydrates. Approximately 10% of the mass of living organisms is hydrogen. Ability of hydrogen to form hydrogen bond plays decisive role in maintaining the spatial quaternary structure of proteins, as well as in implementing the principle of complementarity (cm. COMPLEMENTARY) in the construction and functions of nucleic acids (that is, in storage and implementation genetic information), in general in the implementation of “recognition” on molecular level. Hydrogen (H+ ion) takes part in the most important dynamic processes and reactions in the body - in biological oxidation, which provides living cells with energy, in photosynthesis in plants, in biosynthetic reactions, in nitrogen fixation and bacterial photosynthesis, in the maintenance acid-base balance and homeostasis (cm. HOMEOSTASIS), in processes membrane transport. Thus, along with oxygen and carbon, hydrogen forms the structural and functional basis of life phenomena.
encyclopedic Dictionary. 2009 .
Synonyms:See what “hydrogen” is in other dictionaries:
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