interaction with water form alkali; c) passive, inactive; b) when interacting with metals, they form salts; G) typical metals; 2. A metal that can be used to produce hydrogen (by reacting it with water at n.a.): a) Zn; b) Mg; c) Au; d) Hg; e) K; 3. Oxides and hydroxides that are capable of reacting 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. Side element subgroups VII group: a) chlorine b) phosphorus c) manganese d) francium 6. The charge of the atomic nucleus is determined: a) by the number of the period b) by the group number c) by the serial number 7. The same in the structure of atoms of elements with serial numbers 17 and 35: a ) total electrons; c) quantity electronic levels; d) the number of electrons in the last energy level; b) the number of neutrons; 8. Item with electronic formula 1s22s2p63s2p4: a) carbon; b) sulfur; c) chlorine; d) sodium; 9. The carbon atom has an electronic formula: a) 1s22s22p3 b) 1s22s2 c) 1s22s22p2 10. Which element atom 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. Serial number of the element whose atoms are capable of forming the highest 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 bond type: a) RH4; b) RH3; c) H2R; d) HR; 14. The volume of 3 mol 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 secondary subgroup; oxide and hydroxide exhibit amphoteric character. This element forms oxide type RO and hydroxide R(OH)2. a) magnesium b) calcium c) zinc d) carbon 16. Maximum valency 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 mass salt obtained by the interaction of two higher oxides elements with the configuration of the atom 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 scheme 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 oxide (III) that make up 800 g this connection: a) 1; b) 2; at 3; d) 4; e) 5; 23. During the combustion of 8 g of CH4 methane, 401 kJ of heat was released. Calculate the thermal effect (Q) of the 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: a) 11.2 liters; 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 EO2 compound is 50%. The name of the element E in the compound: a) nitrogen; b) titanium; c) sulfur; d) selenium; e) carbon; 27. The number of moles of iron oxide (III) interacting with 44.8 liters of hydrogen (n.o.): 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.o.) (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, which 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;
Hydrogen is the simplest of all elements and also the most abundant in nature. Older students already know that the reactions of metals such as magnesium and zinc with dilute inorganic acids lead to the formation of hydrogen. They also know about the hydrogen gas test with a characteristic "pop". Hydrogen is included in the formulas of the most simple connections, with which the study of chemistry at school begins, such as water methane sulphuric acid ammonia and ethanol
Hydrogen is the most abundant element in the universe. By existing estimates, hydrogen accounts for over 90% of atoms and approximately 75% of the mass of the universe. Among the elements that exist on Earth, hydrogen is the ninth most abundant. It makes up 0.76% of the Earth's mass and is found in almost as many various compounds like carbon. Most important connection The naturally occurring hydrogen is water. Hydrogen is also found in organic compounds such as coal and oil.
Hydrogen is not only one of the most common elements, it is also completely different from all other elements in a number of its chemical and physical properties. In addition, it forms a special series of compounds. It is the only element for which a unique variety is named. chemical bond(see section 2.1). There are concepts like H-bomb(see section 1.3), a hydrogen bacterium, and even hydrogen energy(see below).
Hydrogen bacteria are able to generate energy by oxidizing hydrogen to water. This energy is needed by hydrogen bacteria to absorb carbon dioxide. Under certain conditions, they are also capable of oxidizing certain organic compounds.
Hydrogen is the only element that is a combustible gas. That is why the Flemish chemist J. B. Van Helmont (1579-1644), who first isolated hydrogen, called it "combustible gas". Under laboratory conditions, hydrogen was first obtained by the action of acid on iron by T. Mayern, and later (in 1672) by R. Boyle. In 1766, hydrogen was carefully studied by the English chemist and physicist G. Cavendish, who called it "combustible air". The name "hydrogen" was introduced by Lavoisier, who formed the Latin term "hydrogen" from Greek words"hydro" (water) and "genes" (giving birth).
Antoine Laurent Lavoisier (1743-1794)
Lavoisier is considered the founder modern chemistry. His most important contribution to chemistry lies in the overthrow of the erroneous theory of phlogiston. According to this theory, all combustible substances consist of two components - phlogiston and scale. When burning a combustible substance, it loses phlogiston and turns into scale (“ash” or “lime”). Lavoisier experimentally showed that oxygen from the air takes part in the combustion process. He also established the role of oxygen in respiration and for the first time began to distinguish between elements and compounds.
Antoine Lavoisier (from a painting by Talstrup).
The structure of the hydrogen atom
The hydrogen atom has the simplest structure: it consists of a nucleus, which is one proton, and one electron, which is located in the ls-orbital surrounding the nucleus (see Section 1.2). Such simple structure causes many unique properties hydrogen. First, the hydrogen atom has only a valence electron shell. Therefore, its only electron is not shielded from the action of the charge of the nucleus by internal electrons. Secondly, this outer shell it is enough to gain or lose only one electron to achieve a stable electronic configuration. Finally, since the hydrogen atom consists of only one electron and one proton, it is very small. Indeed, its covalent radius (0.029 nm) and van der Waals radius (0.12 nm) are minimum values among all elements (see section 2.2). These features explain many distinctive properties hydrogen and its special position in periodic table.
Position in the periodic table
Since the hydrogen atom, losing its single electron, forms a singly charged positive ion, this element is placed at the top of group 1 in the periodic table. However, although hydrogen under certain conditions can acquire
Table 12.1. Ionization energies of hydrogen, lithium and sodium
Table 12.2. Electron affinity of hydrogen, fluorine and chlorine
Table 12.3. Average bond enthalpies in hydrogen, fluorine and chlorine molecules
metallic properties (see Fig. 2.15), under normal conditions it detects only non-metallic properties. A comparison of its ionization energy with the ionization energy of lithium and sodium (Table 12.1) shows that hydrogen is very different from the other elements of group I alkali metals.
The hydrogen atom is also capable, albeit with difficulty, of attaching an electron, forming an ion. By this property, it would seem that it can be placed at the top of group VII along with the halogens. However, hydrogen is not a p-element, and a comparison of its electron affinity (see Section 2.1) with the electron affinity of fluorine and chlorine (Table 12.2) shows that it does not belong in Group VII.
We also note that although hydrogen, like halogens, forms diatomic molecules, the bond in the hydrogen molecule is much stronger than in the molecules of fluorine or chlorine. This can be verified by comparing their bond enthalpies (see Section 5.3), indicated in Table. 12.3.
The most common chemical element in the universe is hydrogen. This is a kind of starting point, because in the periodic table it atomic number equals one. Mankind hopes to be able to learn more about him as one of the most possible Vehicle 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 for everyone famous formula H 2 O.
How we use it
Discovered hydrogen in 1766 Henry Cavendish when analyzing the oxidation reaction of the 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 not even be caught by human 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. Liquid hydrogen is used as rocket fuel.
Hydrogen can become solid, metallic, but for this, ultra-high 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. Also practically developed a way to create fuel cell based on it: 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 full swing, and scientists and engineers are not going to retreat.
Basic information
Hydrogenium (lat.) - hydrogen, first serial number in the periodic table, denoted 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 same conditions- when the metal is attacked by acid. Hydrogen, even by Cavendish himself, for many years was simply called "combustible air." Only in 1783 did Lavoisier prove that water has complex composition, through synthesis and analysis, and four years later he gave the "combustible air" its 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. And the Russian name was proposed in 1824 by M. Solovyov.
In nature, the distribution of this element has no equal. In the lithosphere and hydrosphere 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 the various gases of nebulae and interstellar medium is also made up of hydrogen. It is present in comets, in the atmosphere of a number of planets. Naturally, not in pure form, - then as free H 2, then as methane CH 4, then 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 difference in masses 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 convenient as a model in quantum mechanics when to calculate energy levels 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 the lightest known substances- more than fourteen times lighter than air (recall flying away air balloons on holidays - inside they have just hydrogen). However, helium can boil, liquefy, melt, solidify, and only helium boils and melts at more low 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 hydrogen reaction, 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 acid properties protic acids. Hydrogen bonds are formed with many elements, affecting the properties of both inorganic and organic compounds.
Getting and using
Hydrogen is produced commercially from natural gases- combustible, coke, 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. 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 liquid fuel and solid fuel. 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 to nuclear energy. This, as we remember, isotopes of hydrogen.
Neumyvakin
Hydrogen as a chemical element is so good that it could not help but have its own fans. Ivan Pavlovich Neumyvakin - Doctor of Medical Sciences, Professor, Laureate State Prize and he has 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 fascination with hydrogen is not aimed at making big money, as is now the case in domestic medicine, but on the contrary - to teach people to recover from anything 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 internal cells the body with oxygen, destroys toxins, normalizes acid and alkaline balance, and from here tissues are regenerated, the whole organism is rejuvenated. 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 infarction, stroke 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. Also not recommended this method 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, just 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 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 of Doctors considers 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, N (lat. hydrogenium; a. hydrogen; n. Wasserstoff; f. hydrogene; i. hidrogeno), - a chemical element periodic system elements of Mendeleev, which are simultaneously attributed to 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/Н = (158±2).10 -6 The equilibrium content of 3 Н on the Earth is ~5.10 27 atoms.
Physical properties of hydrogen
Hydrogen was first described in 1766 by the English scientist G. Cavendish. Under normal conditions, hydrogen is a colorless, odorless, and tasteless gas. In nature, in a free state, it is in the form of H 2 molecules. The dissociation energy of the H 2 molecule is 4.776 eV; the ionization potential of the hydrogen atom is 13.595 eV. Hydrogen is the lightest substance of all known, at 0 ° C and 0.1 MPa 0.0899 kg / m 3; boiling point - 252.6 ° C, melting point - 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 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; well soluble in metals - Ni, Pt, Pd, etc. Forms water with oxygen with heat release of 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, the reactions also go with an explosion. 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 mass). 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 the free state, it is present in volcanic and other natural gases, in (0.0001%, by the number of atoms). It makes up the bulk of the mass of the Sun, stars, interstellar gas, gas nebulae. It is present in the atmospheres of planets 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 fluxes).
Obtaining and using hydrogen
Raw material for industrial production hydrogen - refinery gases, gasification products, etc. The main methods for producing hydrogen: the reaction of hydrocarbons with water vapor, incomplete oxidation of hydrocarbons, oxide conversion, water electrolysis. Hydrogen is used for the production of ammonia, alcohols, synthetic gasoline, hydrochloric acid, hydrotreating of petroleum products, cutting metals with a hydrogen-oxygen flame.
Hydrogen is a promising gaseous fuel. Deuterium and tritium have found application in nuclear power engineering.
Hydrogen
HYDROGEN-a; m. A chemical element (H), a light, colorless and odorless gas that combines with oxygen to form water.
◁ Hydrogen, th, th. V connections. V bacteria. V-th bomb(a huge bomb destructive power, whose explosive action is based on thermonuclear reaction). Hydrogenous, th, th.
hydrogen(lat. Hydrogenium), a chemical element of group VII of the periodic system. In nature, there are two stable isotopes (protium and deuterium) and one radioactive isotope (tritium). The molecule is diatomic (H 2). Colorless and odorless gas; density 0.0899 g/l, t kip - 252.76°C. It combines with many elements to form water with oxygen. The most common element in space; 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, 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, a chemical element with atomic number 1, atomic mass 1.00794. chemical symbol hydrogen H is read in our country "ash", as this letter is pronounced in French.
Natural hydrogen is made up 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, trace amounts of the radioactive nuclide, tritium, are always present in natural hydrogen. (cm. TRITIUM) 3 H (half-life T 1/2 12.43 years). Since the nucleus of a hydrogen atom contains only 1 proton (there cannot be less protons in the nucleus of an atom of an element), it is sometimes said that hydrogen forms a natural lower bound periodic system of elements of D. I. Mendeleev (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 also belongs to the 1st group (group IA of alkali metals (cm. ALKALI METALS)), and to the 7th group (group VIIA of halogens (cm. HALOGENS)).
The masses of atoms in 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 most significant). Therefore, unlike the isotopes of all other elements, hydrogen isotopes have special symbols and names. Hydrogen with mass number 1 is called light hydrogen, or protium (lat. Protium, from the Greek protos - the first), denoted by the symbol H, and its nucleus is called a proton (cm. PROTON (elementary particle)), symbol r. Hydrogen with a mass number of 2 is called heavy hydrogen, deuterium (cm. DEUTERIUM)(Latin Deuterium, from Greek deuteros - the second), the symbols 2 H, or D (read "de") are used to designate it, the nucleus d is the deuteron. radioactive isotope with a mass number of 3 is called superheavy hydrogen, or tritium (lat. Tritum, from the Greek tritos - the third), the symbol 2 H or T (read "those"), the nucleus t is a triton.
Configuration of a single electron layer of a neutral unexcited hydrogen atom 1 s 1
. In compounds, it exhibits oxidation states +1 and, less often, -1 (valency I). Radius neutral atom hydrogen 0.024 nm. The ionization energy of the atom is 13.595 eV, the electron affinity is 0.75 eV. On the Pauling scale, the electronegativity of hydrogen is 2.20. Hydrogen is one of the non-metals.
In its free form, it is a light, flammable gas without color, odor or taste.
Discovery history
The release of combustible 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. Famous English physicist and chemist G. Cavendish (cm. Cavendish Henry) in 1766 he investigated this gas and called it "combustible air". When burned, "combustible air" gave water, but Cavendish's adherence to the theory of phlogiston (cm. PHLOGISTON) prevented him from doing correct conclusions. French chemist A. Lavoisier (cm. Lavoisier Antoine Laurent) together with engineer J. Meunier (cm. MEUNIER Jean-Baptiste Marie Charles), using special gasometers, in 1783 carried out the synthesis of water, and then its analysis, decomposing water vapor with red-hot iron. Thus, he established that "combustible air" is part of the water and can be obtained from it. In 1787, Lavoisier came to the conclusion that "combustible air" is a simple substance, and, therefore, is one of the chemical elements. He gave it the name hydrogene (from the Greek hydor - water and gennao - give birth) - "giving birth to water." The establishment of the composition of water put an end to the "phlogiston theory". 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 found 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 for comparing the atomic masses of elements. The mass of the hydrogen atom was assigned a value equal to 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 the upper atmosphere), but it is distributed almost everywhere on Earth in the composition of water. The element hydrogen is found in organic and inorganic compounds living organisms, natural gas, oil, hard coal. It is contained, of course, in the composition of water (about 11% by weight), in various natural crystalline hydrates and minerals, which contain one or more OH hydroxo groups.
Hydrogen as an element dominates the universe. It accounts for about half the mass of the Sun and other stars, it is present in the atmosphere of a number of planets.
Receipt
Hydrogen can be obtained 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. In the production of hydrogen from natural gas (the main component is methane), its catalytic interaction with water vapor and incomplete oxidation with oxygen are carried out:
CH 4 + H 2 O \u003d CO + 3H 2 and CH 4 + 1/2 O 2 \u003d CO 2 + 2H 2
The separation of hydrogen from coke gas and refinery gases is based on their liquefaction during deep cooling and removal from the mixture of gases that are more easily liquefied than hydrogen. In the presence of cheap electricity, hydrogen is obtained by electrolysis of water, passing current through alkali solutions. Under laboratory conditions, hydrogen is easily obtained by the interaction of 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 / m 3) colorless gas. Melting point -259.15 °C, boiling point -252.7 °C. Liquid hydrogen (at the boiling point) has a density of 70.8 kg/m 3 and is the lightest liquid. Standard electrode potential H 2 / H - in aqueous solution 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 highly soluble in some metals (sponge iron and others), especially well in metallic 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 diatomic molecules H 2 . The dissociation constant of H 2 into atoms at 300 K is 2.56 10 -34. The dissociation energy 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, which 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 (p-H 2) (spins have different orientations). Under normal conditions, normal hydrogen is a mixture of 75% o-H 2 and 25% p-H 2 . Physical Properties p- and o-H 2 are slightly different from each other. So, if the boiling point of pure o-H 2 is 20.45 K, then pure p-n 2 - 20.26 K. Turning o-n 2 in p-H 2 is accompanied by the release of 1418 J/mol of heat.
AT scientific literature It has been repeatedly argued that the high pressures(above 10 GPa) and at low temperatures (about 10 K and below), solid hydrogen, which usually crystallizes in a hexagonal molecular-type lattice, can transform into a substance with metallic properties perhaps even a superconductor. However, there is still no unambiguous data on the possibility of such a transition.
The high strength of the chemical bond between the atoms in the H 2 molecule (which, for example, using the method molecular orbitals, can be explained by the fact that in this molecule electron pair located on the bonding orbital, and the antibonding orbital is not populated with electrons) leads to the fact that at room temperature, gaseous hydrogen is chemically inactive. So, without heating, with simple mixing, hydrogen reacts (with an explosion) only with gaseous fluorine:
H 2 + F 2 \u003d 2HF + Q.
If a mixture of hydrogen and chlorine is irradiated at room temperature ultraviolet light, then there is an immediate formation of hydrogen chloride HCl. The reaction of hydrogen with oxygen occurs with an explosion if a catalyst, metallic palladium (or platinum), is introduced into the mixture of these gases. When ignited, a mixture of hydrogen and oxygen (the so-called explosive gas (cm. EXPLOSIVE GAS)) explodes, and an explosion can occur in mixtures in which the hydrogen content is from 5 to 95 volume percent. Pure hydrogen in air or in pure oxygen burns quietly with evolution a large number heat:
H 2 + 1 / 2O 2 \u003d H 2 O + 285.75 kJ / mol
If hydrogen interacts with other non-metals and metals, then only under certain conditions (heating, high pressure, the presence of a catalyst). Thus, hydrogen reacts reversibly with nitrogen at high blood pressure(20-30 MPa and 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 interact directly with boron, silicon, and phosphorus; compounds of these elements with hydrogen are obtained indirectly.
When heated, hydrogen is able to react with alkaline, alkaline earth metals and magnesium with the formation of compounds with an ionic nature of the bond, which contain hydrogen in the oxidation state –1. So, when calcium is heated in a hydrogen atmosphere, a salt-like hydride of the composition CaH 2 is formed. Polymeric aluminum hydride (AlH 3) x - one of the strongest reducing agents - is 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 able to react not only with many simple, but also with complex substances. First of all, it should be noted the ability of hydrogen to reduce many metals from their oxides (such as iron, nickel, lead, tungsten, copper, etc.). So, 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 \u003d 2Fe + 3H 2 O.
It should be noted that only metals located in the series of standard potentials beyond manganese can be reduced from oxides by hydrogen. More active metals(including manganese) are not reduced to metal from oxides.
Hydrogen is capable of adding to a double or triple bond to many organic compounds (these are the so-called hydrogenation reactions). For example, in the presence of a nickel catalyst, hydrogenation of ethylene C 2 H 4 can be carried out, and ethane C 2 H 6 is formed:
C 2 H 4 + H 2 \u003d C 2 H 6.
The interaction of carbon monoxide (II) and hydrogen in industry produces methanol:
2H 2 + CO \u003d CH 3 OH.
In compounds in which a hydrogen atom is connected to an atom of a more electronegative element E (E \u003d F, Cl, O, N), hydrogen bonds form between the molecules (cm. HYDROGEN BOND)(two E atoms of the same or two different elements are interconnected through the H atom: E "... H ... 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 points 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, in the 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 get solid fat - margarine. Liquid hydrogen finds use as a 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 reaction of hydrogen combustion will become the main source of energy production, and hydrogen energy will replace traditional sources of energy production (coal, oil, etc.). At the same time, it was assumed that for the production of hydrogen on a large scale it would be possible to use the electrolysis of water. Water electrolysis is a rather energy-intensive process, and it is currently unprofitable to obtain 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 in large quantities occurs at work nuclear power plants. This heat is of limited use, and the possibility of obtaining hydrogen with its help would solve both the problem of ecology (when hydrogen is burned in air, the amount of environmentally generated harmful substances minimum) and the problem of utilization of medium-temperature heat. However, after Chernobyl disaster the development of nuclear energy is curtailed everywhere, so that the indicated source of energy becomes inaccessible. Therefore, the prospects for the widespread use of hydrogen as an energy source are still shifting at least until the middle of the 21st century.
Features of circulation
Hydrogen is not poisonous, 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 an atmosphere of hydrogen, 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. The ability of hydrogen to form hydrogen bond plays a crucial role in maintaining spatial quaternary structure proteins, as well as in the implementation of the principle of complementarity (cm. COMPLEMENTARY) in the construction and functions of nucleic acids (that is, in the 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, providing living cells with energy, in photosynthesis in plants, in biosynthesis reactions, in nitrogen fixation and bacterial photosynthesis, in maintaining acid-base balance and homeostasis (cm. homeostasis), in membrane transport processes. Thus, along with oxygen and carbon, hydrogen forms the structural and functional basis of the phenomena of life.
encyclopedic Dictionary. 2009 .
Synonyms:See what "hydrogen" is in other dictionaries:
Table of nuclides General information Name, symbol Hydrogen 4, 4H Neutrons 3 Protons 1 Nuclide properties Atomic mass 4.027810 (110) ... Wikipedia
Table of nuclides General information Name, symbol Hydrogen 5, 5H Neutrons 4 Protons 1 Nuclide properties Atomic mass 5.035310 (110) ... Wikipedia
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