Hydrogen was discovered in the second half of the 18th century by the English scientist in the field of physics and chemistry G. Cavendish. He managed to isolate the substance in its pure state, began studying it and described its properties.

This is the story of the discovery of hydrogen. During the experiments, the researcher determined that it is a flammable gas, the combustion of which in the air produces water. This led to the determination of the qualitative composition of water.

What is hydrogen

The French chemist A. Lavoisier first announced hydrogen as a simple substance in 1784, since he determined that its molecule contains atoms of the same type.

The name of the chemical element in Latin sounds like hydrogenium (read “hydrogenium”), which means “water-giving.” The name refers to the combustion reaction that produces water.

Characteristics of hydrogen

Designation of hydrogen N. Mendeleev assigned the first atomic number to this chemical element, placing it in the main subgroup of the first group and the first period and conditionally in the main subgroup of the seventh group.

The atomic weight (atomic mass) of hydrogen is 1.00797. The molecular weight of H2 is 2 a. e. The molar mass is numerically equal to it.

It is represented by three isotopes that have a special name: the most common protium (H), heavy deuterium (D), radioactive tritium (T).

It is the first element that can be completely separated into isotopes in a simple manner. It is based on the high difference in mass of isotopes. The process was first carried out in 1933. This is explained by the fact that only in 1932 an isotope with mass 2 was discovered.

Physical properties

Under normal conditions, the simple substance hydrogen in the form of diatomic molecules is a gas, colorless, tasteless and odorless. Slightly soluble in water and other solvents.

Crystallization temperature - 259.2 o C, boiling point - 252.8 o C. The diameter of hydrogen molecules is so small that they have the ability to slowly diffuse through a number of materials (rubber, glass, metals). This property is used when it is necessary to purify hydrogen from gaseous impurities. When n. u. hydrogen has a density of 0.09 kg/m3.

Is it possible to transform hydrogen into a metal by analogy with the elements located in the first group? Scientists have found that hydrogen, under conditions when the pressure approaches 2 million atmospheres, begins to absorb infrared rays, which indicates the polarization of the molecules of the substance. Perhaps, at even higher pressures, hydrogen will become a metal.

This is interesting: there is an assumption that on the giant planets, Jupiter and Saturn, hydrogen is found in the form of a metal. It is assumed that metallic solid hydrogen is also present in the earth's core, due to the ultra-high pressure created by the earth's mantle.

Chemical properties

Both simple and complex substances enter into chemical interaction with hydrogen. But the low activity of hydrogen needs to be increased by creating appropriate conditions - increasing the temperature, using catalysts, etc.

When heated, simple substances such as oxygen (O 2), chlorine (Cl 2), nitrogen (N 2), sulfur (S) react with hydrogen.

If you ignite pure hydrogen at the end of a gas outlet tube in air, it will burn evenly, but barely noticeably. If you place the gas outlet tube in an atmosphere of pure oxygen, then combustion will continue with the formation of water droplets on the walls of the vessel, as a result of the reaction:

The combustion of water is accompanied by the release of a large amount of heat. This is an exothermic compound reaction in which hydrogen is oxidized by oxygen to form the oxide H 2 O. It is also a redox reaction in which hydrogen is oxidized and oxygen is reduced.

The reaction with Cl 2 occurs similarly to form hydrogen chloride.

The interaction of nitrogen with hydrogen requires high temperature and high pressure, as well as the presence of a catalyst. The result is ammonia.

As a result of the reaction with sulfur, hydrogen sulfide is formed, the recognition of which is facilitated by the characteristic smell of rotten eggs.

The oxidation state of hydrogen in these reactions is +1, and in the hydrides described below – 1.

When reacting with some metals, hydrides are formed, for example, sodium hydride - NaH. Some of these complex compounds are used as fuel for rockets, as well as in thermonuclear power.

Hydrogen also reacts with substances from the complex category. For example, with copper (II) oxide, formula CuO. To carry out the reaction, copper hydrogen is passed over heated powdered copper (II) oxide. During the interaction, the reagent changes its color and becomes red-brown, and droplets of water settle on the cold walls of the test tube.

Hydrogen is oxidized during the reaction, forming water, and copper is reduced from oxide to a simple substance (Cu).

Applications

Hydrogen is of great importance for humans and is used in a variety of fields:

1. In chemical production it is raw materials, in other industries it is fuel. Petrochemical and oil refining enterprises cannot do without hydrogen.
2. In the electric power industry, this simple substance acts as a cooling agent.
3. In ferrous and non-ferrous metallurgy, hydrogen plays the role of a reducing agent.
4. This helps create an inert environment when packaging products.
5. Pharmaceutical industry - uses hydrogen as a reagent in the production of hydrogen peroxide.
6. Weather balloons are filled with this light gas.
7. This element is also known as a fuel reducer for rocket engines.

Scientists unanimously predict that hydrogen fuel will take the lead in the energy sector.

Receipt in industry

In industry, hydrogen is produced by electrolysis, which is subjected to chlorides or hydroxides of alkali metals dissolved in water. It is also possible to obtain hydrogen directly from water using this method.

The conversion of coke or methane with water vapor is used for these purposes. The decomposition of methane at elevated temperatures also produces hydrogen. Liquefaction of coke oven gas by the fractional method is also used for the industrial production of hydrogen.

Obtained in the laboratory

In the laboratory, a Kipp apparatus is used to produce hydrogen.

The reagents are hydrochloric or sulfuric acid and zinc. The reaction produces hydrogen.

Finding hydrogen in nature

Hydrogen is more common than any other element in the Universe. The bulk of stars, including the Sun, and other cosmic bodies is hydrogen.

In the earth's crust it is only 0.15%. It is present in many minerals, in all organic substances, as well as in water, which covers 3/4 of the surface of our planet.

Traces of pure hydrogen can be found in the upper atmosphere. It is also found in a number of flammable natural gases.

Gaseous hydrogen is the least dense, and liquid hydrogen is the densest substance on our planet. With the help of hydrogen, you can change the timbre of your voice if you inhale it and speak as you exhale.

The most powerful hydrogen bomb is based on the splitting of the lightest atom.

The works of chemists of the 16th and 17th centuries repeatedly mentioned the release of flammable gas when acids act on metals. In 1766, G. Cavendish collected and studied the gas released, calling it “combustible air.” Being a supporter of the phlogiston theory, Cavendish believed that this gas was pure phlogiston. In 1783, A. Lavoisier, through the analysis and synthesis of water, proved the complexity of its composition, and in 1787 he identified “combustible air” as a new chemical element (Hydrogen) and gave it the modern name hydrogene (from the Greek hydor - water and gennao - I give birth), which means "giving birth to water"; this root is used in the names of Hydrogen compounds and processes with its participation (for example, hydrides, hydrogenation). The modern Russian name "Hydrogen" was proposed by M. F. Solovyov in 1824.

Distribution of Hydrogen in nature. Hydrogen is widespread in nature; its content in the earth's crust (lithosphere and hydrosphere) is 1% by mass and 16% by number of atoms. Hydrogen is part of the most common substance on Earth - water (11.19% of Hydrogen by mass), in the composition of compounds that make up coal, oil, natural gases, clays, as well as animal and plant organisms (that is, in the composition of proteins, nucleic acids , fats, carbohydrates and others). Hydrogen is extremely rare in its free state; it is found in small quantities in volcanic and other natural gases. Minor amounts of free Hydrogen (0.0001% by number of atoms) are present in the atmosphere. In near-Earth space, Hydrogen in the form of a flow of protons forms the internal (“proton”) radiation belt of the Earth. In space, Hydrogen is the most abundant element. In the form of plasma, it makes up about half the mass of the Sun and most stars, the bulk of the gases of the interstellar medium and gaseous nebulae. Hydrogen is present in the atmosphere of a number of planets and in comets in the form of free H 2, methane CH 4, ammonia NH 3, water H 2 O, radicals such as CH, NH, OH, SiH, PH, etc. Hydrogen enters in the form of a flow of protons into the corpuscular radiation of the Sun and cosmic rays.

Isotopes, atom and molecule of Hydrogen. Ordinary Hydrogen consists of a mixture of 2 stable isotopes: light Hydrogen, or protium (1 H), and heavy Hydrogen, or deuterium (2 H, or D). In natural compounds of Hydrogen, there are on average 6800 atoms of 1 H per 1 atom of 2 H. A radioactive isotope with a mass number of 3 is called superheavy Hydrogen, or tritium (3 H, or T), with soft β-radiation and a half-life T ½ = 12.262 years . In nature, tritium is formed, for example, from atmospheric nitrogen under the influence of cosmic ray neutrons; in the atmosphere it is negligibly small (4·10 -15% of the total number of Hydrogen atoms). An extremely unstable isotope 4 H was obtained. The mass numbers of the isotopes 1 H, 2 H, 3 H and 4 H, respectively 1, 2, 3 and 4, indicate that the nucleus of the protium atom contains only one proton, and that of deuterium - one proton and one neutron, tritium - one proton and 2 neutrons, 4 H - one proton and 3 neutrons. The large difference in the masses of Hydrogen isotopes causes a more noticeable difference in their physical and chemical properties than in the case of isotopes of other elements.

The Hydrogen atom has the simplest structure among the atoms of all other elements: it consists of a nucleus and one electron. The binding energy of an electron with a nucleus (ionization potential) is 13.595 eV. The neutral hydrogen atom can also attach a second electron, forming a negative H ion - in this case, the binding energy of the second electron with a neutral atom (electron affinity) is 0.78 eV. Quantum mechanics allows us to calculate all possible energy levels of the Hydrogen atom, and therefore give a complete interpretation of its atomic spectrum. The Hydrogen atom is used as a model atom in quantum mechanical calculations of the energy levels of other, more complex atoms.

The Hydrogen H2 molecule consists of two atoms connected by a covalent chemical bond. The energy of dissociation (that is, decay into atoms) is 4.776 eV. The interatomic distance at the equilibrium position of the nuclei is 0.7414 Å. At high temperatures, molecular Hydrogen dissociates into atoms (the degree of dissociation at 2000°C is 0.0013, at 5000°C 0.95). Atomic Hydrogen is also formed in various chemical reactions (for example, by the action of Zn on hydrochloric acid). However, the existence of Hydrogen in the atomic state lasts only a short time; the atoms recombine into H 2 molecules.

Physical properties of Hydrogen. Hydrogen is the lightest of all known substances (14.4 times lighter than air), density 0.0899 g/l at 0°C and 1 atm. Hydrogen boils (liquefies) and melts (solidifies) at -252.8°C and -259.1°C, respectively (only helium has lower melting and boiling points). The critical temperature of Hydrogen is very low (-240°C), so its liquefaction is fraught with great difficulties; critical pressure 12.8 kgf/cm 2 (12.8 atm), critical density 0.0312 g/cm 3. Of all gases, Hydrogen has the highest thermal conductivity, equal to 0.174 W/(m·K) at 0°C and 1 atm, that is, 4.16·10 -4 cal/(s·cm·°C). The specific heat of Hydrogen at 0°C and 1 atm C p 14.208 kJ/(kg·K), that is, 3.394 cal/(g·°С). Hydrogen is slightly soluble in water (0.0182 ml/g at 20°C and 1 atm), but well soluble in many metals (Ni, Pt, Pa and others), 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). Liquid Hydrogen is very light (density at -253°C 0.0708 g/cm 3) and fluid (viscosity at -253°C 13.8 spuaz).

Chemical properties of Hydrogen. In most compounds, Hydrogen exhibits a valence (more precisely, oxidation state) +1, like sodium and other alkali metals; it is usually considered as an analogue of these metals, heading group I of the periodic system. However, in metal hydrides, the Hydrogen ion is negatively charged (oxidation state -1), that is, the hydride Na + H - is built similar to the chloride Na + Cl -. This and some other facts (the similarity of the physical properties of Hydrogen and halogens, the ability of halogens to replace Hydrogen in organic compounds) give grounds to classify Hydrogen also in Group VII of the periodic table. Under ordinary conditions, molecular Hydrogen is relatively little active, directly combining only with the most active of non-metals (with fluorine, and in the light with chlorine). However, when heated, it reacts with many elements. Atomic Hydrogen has increased chemical activity compared to molecular Hydrogen. With oxygen, hydrogen forms water:

H 2 + 1/2 O 2 = H 2 O

with the release of 285.937 kJ/mol, that is, 68.3174 kcal/mol of heat (at 25°C and 1 atm). At normal temperatures the reaction proceeds extremely slowly, above 550°C it explodes. The explosive limits of a hydrogen-oxygen mixture are (by volume) from 4 to 94% H2, and of a hydrogen-air mixture - from 4 to 74% H2 (a mixture of 2 volumes of H2 and 1 volume of O2 is called detonating gas). Hydrogen is used to reduce many metals, as it removes oxygen from their oxides:

CuO + H 2 = Cu + H 2 O,

Fe 3 O 4 + 4H 2 = 3Fe + 4H 2 O, etc.

With halogens Hydrogen forms hydrogen halides, for example:

H 2 + Cl 2 = 2HCl.

At the same time, Hydrogen explodes with fluorine (even in the dark and at - 252°C), reacts with chlorine and bromine only when illuminated or heated, and with iodine only when heated. Hydrogen reacts with nitrogen to form ammonia:

ZN 2 + N 2 = 2NH 3

only on a catalyst and at elevated temperatures and pressures. When heated, Hydrogen reacts vigorously with sulfur:

H 2 + S = H 2 S (hydrogen sulfide),

much more difficult with selenium and tellurium. Hydrogen can react with pure carbon without a catalyst only at high temperatures:

2H 2 + C (amorphous) = CH 4 (methane).

Hydrogen reacts directly with some metals (alkali, alkaline earth and others), forming hydrides:

H 2 + 2Li = 2LiH.

Of great practical importance are the reactions of Hydrogen with carbon monoxide (II), in which various organic compounds are formed, depending on temperature, pressure and catalyst, for example HCHO, CH 3 OH and others. Unsaturated hydrocarbons react with Hydrogen, becoming saturated, for example:

C n H 2n + H 2 = C n H 2n+2.

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

Obtaining Hydrogen. The main types of raw materials for the industrial production of Hydrogen are natural flammable gases, coke oven gas and oil refining gases. Hydrogen is also obtained from water by electrolysis (in places with cheap electricity). The most important methods for producing Hydrogen from natural gas are the catalytic interaction of hydrocarbons, mainly methane, with water vapor (conversion):

CH 4 + H 2 O = CO + ZN 2,

and incomplete oxidation of hydrocarbons with oxygen:

CH 4 + 1/2 O 2 = CO + 2H 2

The resulting carbon monoxide (II) also undergoes conversion:

CO + H 2 O = CO 2 + H 2.

Hydrogen produced from natural gas is the cheapest.

Hydrogen is isolated from coke oven gas and oil refining gases by removing the remaining components of the gas mixture, which liquefy more easily than Hydrogen during deep cooling. Electrolysis of water is carried out with direct current, passing it through a solution of KOH or NaOH (acids are not used to avoid corrosion of steel equipment). In laboratories, Hydrogen is obtained by electrolysis of water, as well as by the reaction between zinc and hydrochloric acid. However, more often they use ready-made hydrogen in cylinders.

Application of Hydrogen. Hydrogen began to be produced on an industrial scale at the end of the 18th century to fill balloons. Currently, Hydrogen is widely used in the chemical industry, mainly for the production of ammonia. A major consumer of Hydrogen is also the production of methyl and other alcohols, synthetic gasoline and other products obtained by synthesis from Hydrogen and carbon monoxide (II). Hydrogen is used for the hydrogenation of solid and heavy liquid fuels, fats and others, for the synthesis of HCl, for the hydrotreatment of petroleum products, in welding and cutting of metals with an oxygen-hydrogen flame (temperature up to 2800°C) and in atomic-hydrogen welding (up to 4000°C) . Hydrogen isotopes - deuterium and tritium - have found very important applications in nuclear energy.

HYDROGEN (Latin Hydrogenium), H, chemical element of group VII of the short form (group 1 of the long form) of the periodic system; atomic number 1, atomic mass 1.00794; non-metal. There are two stable isotopes in nature: protium 1H (99.985% by mass) and deuterium D, or 2H (0.015%). Artificially produced radioactive tritium 3 H, or T (ß-decay, T 1/2 12.26 years), is formed in nature in negligible quantities in the upper layers of the atmosphere as a result of the interaction of cosmic radiation mainly with N and O nuclei. Artificially obtained extremely unstable radioactive isotopes 4 H, 5 H, 6 H.

Historical information. Hydrogen was first studied in 1766 by G. Cavendish and he called it “flammable air.” In 1787, A. Lavoisier showed that this gas forms water when burned, included it in the list of chemical elements and proposed the name hydrogène (from the Greek?δωρ - water and γενν?ω - to give birth).

Prevalence in nature. The hydrogen content in atmospheric air is 3.5-10% by mass, in the earth's crust 1%. The main reservoir of hydrogen on Earth is water (11.19% hydrogen by mass). Hydrogen is a biogenic element and is part of compounds that form coal, oil, natural combustible gases, many minerals, etc. In near-Earth space, hydrogen in the form of a flow of protons forms the Earth's internal radiation belt. Hydrogen is the most abundant element in space; in the form of plasma it makes up about 70% of the mass of the Sun and stars, the bulk of the interstellar medium and gaseous nebulae, is present in the atmosphere of a number of planets in the form of H 2, CH 4, NH 3, H 2 O, etc.

Properties. The configuration of the electron shell of the hydrogen atom is 1s 1; in compounds exhibits oxidation states +1 and -1. Electronegativity according to Pauling 2.1; radii (pm): atomic 46, covalent 30, van der Waals 120; ionization energy Н°→ Н + 1312.0 kJ/mol. In the free state, hydrogen forms a diatomic H 2 molecule, the internuclear distance is 76 pm, the dissociation energy is 432.1 kJ/mol (0 K). Depending on the relative orientation of the nuclear spins, there are ortho-hydrogen (parallel spins) and para-hydrogen (antiparallel spins), differing in magnetic, optical and thermal properties and usually contained in a 3:1 ratio; the conversion of para-hydrogen to ortho-hydrogen requires 1418 J/mol of energy.

Hydrogen is a colorless, tasteless and odorless gas; t PL -259.19 °C, t KIP -252.77 °C. Hydrogen is the lightest and most thermally conductive of all gases: at 273 K, density is 0.0899 kg/m 3, thermal conductivity is 0.1815 W/(m K). Insoluble in water; dissolves well in many metals (best in Pd - up to 850% by volume); diffuses through many materials (eg steel). Burns in air and forms explosive mixtures. Solid hydrogen crystallizes in a hexagonal lattice; at pressures above 10 4 MPa, a phase transition is possible with the formation of a structure built from atoms and possessing metallic properties - the so-called metallic hydrogen.

Hydrogen forms compounds with many elements. With oxygen it forms water (at temperatures above 550 °C the reaction is accompanied by an explosion), with nitrogen - ammonia, with halogens - hydrogen halides, with metals, intermetallic compounds, as well as with many non-metals (for example, chalcogens) - hydrides, with carbon - hydrocarbons. Reactions with CO are of practical importance (see Synthesis gas). Hydrogen reduces the oxides and halides of many metals to metals, and unsaturated hydrocarbons to saturated ones (see Hydrogenation). The nucleus of the hydrogen atom - the H + proton - determines the acidic properties of compounds. In aqueous solutions, H + forms hydronium ion H 3 O + with a water molecule. In the molecules of various compounds, hydrogen tends to form hydrogen bonds with many electronegative elements.

Application. Hydrogen gas is used in the industrial synthesis of ammonia, hydrochloric acid, methanol and higher alcohols, synthetic liquid fuels, etc., for the hydrogenation of fats and other organic compounds; in oil refining - for hydrotreating and hydrocracking of oil fractions; in metallurgy - to obtain metals (for example, W, Mo, Re from their oxides and fluorides), to create a protective environment when processing metals and alloys; in the production of quartz glass products using a hydrogen-oxygen flame, for atomic-hydrogen welding of refractory steels and alloys, etc., as lifting gas for balloons. Liquid hydrogen is a fuel in rocket and space technology; also used as a refrigerant.

For information on the main methods of production, as well as storage, transportation and use of hydrogen as an energy carrier, see Hydrogen Energy.

Lit. look at Art. Hydrogen energy.

Chemical properties of hydrogen

Under ordinary conditions, molecular Hydrogen is relatively little active, directly combining only with the most active of non-metals (with fluorine, and in the light with chlorine). However, when heated, it reacts with many elements.

Hydrogen reacts with simple and complex substances:

- Interaction of hydrogen with metals leads to the formation of complex substances - hydrides, in the chemical formulas of which the metal atom always comes first:

At high temperature, Hydrogen reacts directly with some metals(alkaline, alkaline earth and others), forming white crystalline substances - metal hydrides (Li H, Na H, KH, CaH 2, etc.):

H 2 + 2Li = 2LiH

Metal hydrides are easily decomposed by water to form the corresponding alkali and hydrogen:

Sa H 2 + 2H 2 O = Ca(OH) 2 + 2H 2

- When hydrogen interacts with non-metals volatile hydrogen compounds are formed. In the chemical formula of a volatile hydrogen compound, the hydrogen atom can be in either the first or second place, depending on its location in the PSHE (see plate in the slide):

1). With oxygen Hydrogen forms water:

Video "Hydrogen combustion"

2H 2 + O 2 = 2H 2 O + Q

At normal temperatures the reaction proceeds extremely slowly, above 550°C - with explosion (a mixture of 2 volumes of H 2 and 1 volume of O 2 is called explosive gas) .

Video "Explosion of detonating gas"

Video "Preparation and explosion of an explosive mixture"

2). With halogens Hydrogen forms hydrogen halides, for example:

H 2 + Cl 2 = 2HCl

At the same time, Hydrogen explodes with fluorine (even in the dark and at - 252°C), reacts with chlorine and bromine only when illuminated or heated, and with iodine only when heated.

3). With nitrogen Hydrogen reacts to form ammonia:

ZN 2 + N 2 = 2NH 3

only on a catalyst and at elevated temperatures and pressures.

4). When heated, Hydrogen reacts vigorously with sulfur:

H 2 + S = H 2 S (hydrogen sulfide),

much more difficult with selenium and tellurium.

5). With pure carbon Hydrogen can react without a catalyst only at high temperatures:

2H 2 + C (amorphous) = CH 4 (methane)

- Hydrogen undergoes a substitution reaction with metal oxides , in this case water is formed in the products and the metal is reduced. Hydrogen - exhibits the properties of a reducing agent:

Hydrogen is used for the recovery of many metals, since it takes oxygen away from their oxides:

Fe 3 O 4 + 4H 2 = 3Fe + 4H 2 O, etc.

Applications of hydrogen

Video "Using Hydrogen"

Currently, hydrogen is produced in huge quantities. A very large part of it is used in the synthesis of ammonia, hydrogenation of fats and in the hydrogenation of coal, oils and hydrocarbons. In addition, hydrogen is used for the synthesis of hydrochloric acid, methyl alcohol, hydrocyanic acid, in welding and forging metals, as well as in the manufacture of incandescent lamps and precious stones. Hydrogen is sold in cylinders under a pressure of over 150 atm. They are painted dark green and have a red inscription "Hydrogen".

Hydrogen is used to convert liquid fats into solid fats (hydrogenation), producing liquid fuel by hydrogenating coal and fuel oil. In metallurgy, hydrogen is used as a reducing agent for oxides or chlorides to produce metals and non-metals (germanium, silicon, gallium, zirconium, hafnium, molybdenum, tungsten, etc.).

The practical uses of hydrogen are varied: it is usually used to fill probe balloons, in the chemical industry it serves as a raw material for the production of many very important products (ammonia, etc.), in the food industry - for the production of solid fats from vegetable oils, etc. High temperature (up to 2600 °C), obtained by burning hydrogen in oxygen, is used for melting refractory metals, quartz, etc. Liquid hydrogen is one of the most efficient jet fuels. Annual global consumption of hydrogen exceeds 1 million tons.

SIMULATORS

No. 2. Hydrogen

ASSIGNMENT TASKS

Task No. 1
Write down reaction equations for the interaction of hydrogen with the following substances: F 2, Ca, Al 2 O 3, mercury (II) oxide, tungsten (VI) oxide. Name the reaction products, indicate the types of reactions.

Task No. 2
Carry out transformations according to the scheme:
H 2 O -> H 2 -> H 2 S -> SO 2

Task No. 3.
Calculate the mass of water that can be obtained by burning 8 g of hydrogen?

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

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

Hydrogen as a chemical element

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

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

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

Simple substance

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

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

Laboratory methods for producing hydrogen:

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

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

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

Areas of use

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

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

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

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

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

Hydrogen compounds

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

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

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

- this is the best solvent

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

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

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

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

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

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

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

Hydrogen peroxide is a universal remedy

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

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

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