Chemical properties of hydrogen reaction. Chemical properties of hydrogen: features and applications. Hydrogen in mineral compounds

In the periodic system, it has its definite place of position, which reflects the properties manifested by it and speaks of its electronic structure. However, there is one special atom among all, which occupies two cells at once. It is located in two groups of elements that are completely opposite in terms of the manifested properties. This is hydrogen. These features make it unique.

Hydrogen is not just an element, but also a simple substance, as well as a component of many complex compounds, a biogenic and organogenic element. Therefore, we will 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 small 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 ordinal number of hydrogen is 1, the number of electrons is the same, respectively, the number of protons is the same. The atomic mass is 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 the outside allows it to successfully exhibit both oxidizing and reducing properties. In addition, after the release of an electron, it has a free orbital, which takes part in the formation chemical bonds by donor-acceptor mechanism.
3. Hydrogen is a powerful reducing agent. Therefore, its main place is considered the first group of the main subgroup, where it is headed by the most active metals - alkali.
4. However, when interacting with strong reducing agents, such as, for example, metals, it can also be an oxidizing agent, accepting an electron. These compounds are called hydrides. On this basis, he heads the subgroup of halogens, with which he 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 the benchmark for lightness.

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

Simple substance

If we talk about this element as a molecule, then it must be said that it is diatomic. That is, hydrogen (a simple substance) is a gas. Its empirical formula will be written as H 2, and its graphical formula - through a single sigma-relationship H-H. The mechanism of bond formation between atoms is covalent non-polar.

1. Steam reforming of methane.
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 melts do not lead to the discharge of water at the cathode.

Laboratory methods obtaining hydrogen:

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

To collect the generated hydrogen, the tube must be held 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. Evaporates quickly, and explodes in large quantities when mixed with air. Therefore, the 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 lighted match to the neck. If the cotton is dull and quiet, then the gas is clean, with minimal air impurities. If it is loud and whistling, it is dirty, with a large proportion of extraneous components.

Areas of use

When hydrogen burns, so much 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 the ill-conceived and unsolved problems of the synthesis of pure hydrogen, which would be suitable for use as fuel in reactors, engines and portable devices, as well as heating boilers in residential buildings.

After all, the methods of obtaining this gas are quite expensive, therefore, first it is necessary to develop a special synthesis method. One that will allow you to get a product in large quantities and at minimal cost.

There are several main areas in which the gas we are considering finds application.

1. Chemical syntheses. Hydrogenation produces 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 an additive E949.
3. Aviation industry (rocketry, aircraft construction).
4. Power engineering.
5. Meteorology.
6. Environmentally friendly fuel.

Obviously, hydrogen is just as important as it is in nature. An even greater role is played by the various compounds formed by it.

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 hydrochloric acid solution. This acid is widely used in almost all chemical syntheses. And both organic and inorganic. Hydrogen chloride is a compound with the empirical formula HCL and is one of the largest in terms of production in our country every year. 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. Moreover, it is very flammable.
3. Hydrides are compounds with metals. They belong to the class of salts.
4. Hydroxides: bases, acids and amphoteric compounds. They necessarily include 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 for hydrogen oxide. The empirical formula looks like this - H 2 O.
6. Hydrogen peroxide. It is the strongest oxidizing agent, the formula of which is Н 2 О 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 great. This once again confirms its high importance for nature and man, as well as for all living beings.

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, which explains many of its properties. In particular, it is a universal solvent.

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

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

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

There are three types of water depending on the hydrogen isotope that is part of the molecule.

1. Lightweight or protium. An isotope with a mass number of 1. Formula - H 2 O. This is a common form used by all organisms.
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, the isotope is 3 N.

The reserves of fresh protium water on the planet are very important. Already now in many countries there is a lack of it. Methods are being developed for the treatment of salt water in order to obtain drinking water.

Hydrogen peroxide is a versatile remedy

This compound, as mentioned above, is an excellent oxidizing agent. However, with strong representatives it can behave as a restorer too. 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 in order to disinfect them. However, it has been proven that in this case, wound healing increases over time.

Hydrogen peroxide is also used in rocket fuel, in industry for disinfection and bleaching, as a foaming agent to obtain appropriate materials (foam, for example). In addition, peroxide helps clean aquariums, bleach hair, and whiten teeth. However, at the same time it damages the tissues, so it is not recommended by specialists for these purposes.

• Designation - H (Hydrogen);
• Latin name - Hydrogenium;
• Period - I;
• Group - 1 (Ia);
• Atomic mass - 1.00794;
• Atomic number - 1;
• Atom radius = 53 pm;
• Covalent radius = 32 pm;
• Distribution of electrons - 1s 1;
• melting point = -259.14 ° C;
• boiling point = -252.87 ° C;
• Electronegativity (Pauling / Alpred and Rohov) = 2.02 / -;
• Oxidation state: +1; 0; -1;
• Density (n. At.) = 0.0000899 g / cm 3;
• Molar volume = 14.1 cm 3 / mol.

Binary compounds of hydrogen with oxygen:

Hydrogen ("giving birth to water") was discovered by the English scientist G. Cavendish in 1766. It is the simplest element in nature - a hydrogen atom has a nucleus and one electron, which is probably why hydrogen is the most abundant element in the Universe (it makes up more than half the mass of most stars).

About hydrogen we can say that "the spool is small, but expensive." Despite its "simplicity", hydrogen gives energy to all living things on Earth - there is a continuous thermonuclear reaction on the Sun, during which one helium atom is formed from four hydrogen atoms, this process accompanied by the release of a colossal amount of energy (for more details see Nuclear Fusion).

V earth crust the mass fraction of hydrogen is only 0.15%. Meanwhile, the overwhelming number (95%) of all known on Earth chemical substances contain one or more hydrogen atoms.

In compounds with non-metals (HCl, H 2 O, CH 4 ...), hydrogen gives up its only electron to more electronegative elements, exhibiting an oxidation state of +1 (more often), forming only covalent bonds (see Covalent bond).

In compounds with metals (NaH, CaH 2 ...), hydrogen, on the contrary, takes another electron into its only s-orbital, thus trying to complete its electronic layer, showing an oxidation state of -1 (less often), more often forming an ionic bond (see Ionic bond), since the difference in the electronegativity of a hydrogen atom and a metal atom can be quite large.

H 2

In the gaseous state, hydrogen is in the form of diatomic molecules, forming a non-polar covalent bond.

Hydrogen molecules possess:

• great mobility;
• great durability;
• low polarizability;
• small size and weight.

Hydrogen gas properties:

• the lightest gas in nature, colorless and odorless;
• poorly soluble in water and organic solvents;
• in small amounts it dissolves in liquid and solid metals (especially in platinum and palladium);
• difficult to liquefy (due to its low polarizability);
• has the highest thermal conductivity of all known gases;
• when heated, it reacts with many non-metals, exhibiting the properties of a reducing agent;
• at room temperature reacts with fluorine (explosion occurs): H 2 + F 2 = 2HF;
• reacts with metals to form hydrides, showing oxidizing properties: H 2 + Ca = CaH 2;

In compounds, hydrogen manifests its reducing properties much more strongly than oxidizing ones. Hydrogen is the strongest reducing agent after coal, aluminum and calcium. The reducing properties of hydrogen are widely used in industry for the production of metals and non-metals (simple substances) from oxides and gallides.

Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O

Reactions of hydrogen with simple substances

Hydrogen takes on an electron, playing a role reductant, in reactions:

• with oxygen(when ignited or in the presence of a catalyst), in a ratio of 2: 1 (hydrogen: oxygen), an explosive oxyhydrogen gas is formed: 2H 2 0 + O 2 = 2H 2 +1 O + 572 kJ
• with gray(when heated to 150 ° C-300 ° C): H 2 0 + S ↔ H 2 +1 S
• with chlorine(when ignited or irradiated with UV rays): H 2 0 + Cl 2 = 2H +1 Cl
• with fluorine: H 2 0 + F 2 = 2H +1 F
• with nitrogen(when heated in the presence of catalysts or at high pressure): 3H 2 0 + N 2 ↔ 2NH 3 +1

Hydrogen donates an electron, playing a role oxidizer, in reactions with alkaline and alkaline earth metals with the formation of metal hydrides - salt-like ionic compounds containing hydride ions H - are unstable crystalline substances of white color.

Ca + H 2 = CaH 2 -1 2Na + H 2 0 = 2NaH -1

It is unusual for hydrogen to exhibit an oxidation state of -1. Reacting with water, hydrides decompose, reducing water to hydrogen. The reaction of calcium hydride with water is as follows:

CaH 2 -1 + 2H 2 +1 0 = 2H 2 0 + Ca (OH) 2

Reactions of hydrogen with complex substances

• at high temperatures, hydrogen reduces many metal oxides: ZnO + H 2 = Zn + H 2 O
• methyl alcohol is obtained as a result of the reaction of hydrogen with carbon monoxide (II): 2H 2 + CO → CH 3 OH
• in hydrogenation reactions, hydrogen reacts with many organic substances.

The equations of chemical reactions of hydrogen and its compounds are considered in more detail on the page "Hydrogen and its compounds - equations of chemical reactions involving hydrogen".

Application of hydrogen

• v nuclear power isotopes of hydrogen are used - deuterium and tritium;
• in the chemical industry, hydrogen is used for the synthesis of many organic substances, ammonia, hydrogen chloride;
• in the food industry, hydrogen is used in the production of solid fats through the hydrogenation of vegetable oils;
• high temperature of combustion of hydrogen in oxygen (2600 ° C) is used for welding and cutting metals;
• in the production of some metals, hydrogen is used as a reducing agent (see above);
• since hydrogen is a light gas, it is used in aeronautics as a filler for balloons, balloons, airships;
• as a fuel, hydrogen is used in a mixture with CO.

Recently, scientists have been paying a lot of attention to finding alternative sources of renewable energy. One of the promising areas is "hydrogen" energy, in which hydrogen is used as a fuel, the combustion product of which is ordinary water.

Methods for producing hydrogen

Industrial methods for producing hydrogen:

• conversion of methane (catalytic reduction of water vapor) with water vapor at high temperature (800 ° C) on a nickel catalyst: CH 4 + 2H 2 O = 4H 2 + CO 2;
• conversion of carbon monoxide with steam (t = 500 ° C) on the catalyst Fe 2 O 3: CO + H 2 O = CO 2 + H 2;
• thermal decomposition of methane: CH 4 = C + 2H 2;
• gasification of solid fuels (t = 1000 ° C): C + H 2 O = CO + H 2;
• electrolysis of water (a very expensive method in which very pure hydrogen is obtained): 2H 2 O → 2H 2 + O 2.

Laboratory methods for producing hydrogen:

• the action on metals (usually zinc) with hydrochloric or dilute sulfuric acid: Zn + 2HCl = ZCl 2 + H 2; Zn + H 2 SO 4 = ZnSO 4 + H 2;
• interaction of water vapor with hot iron shavings: 4H 2 O + 3Fe = Fe 3 O 4 + 4H 2.

Hydrogen H is a chemical element, one of the most widespread in our Universe. The mass of hydrogen as an element in the composition of substances is 75% of the total content of atoms of another type. He enters into the most important and vital connection on the planet - water. A distinctive feature of hydrogen is also the fact that it is the first element in the periodic system of chemical elements of D.I.Mendeleev.

Discovery and exploration

The first mention of hydrogen in the writings of Paracelsus dates back to the sixteenth century. But its separation from the gas mixture of air and the study of the combustible properties were carried out already in the seventeenth century by the scientist Lemery. Hydrogen was thoroughly studied by an English chemist, physicist and naturalist who empirically proved that the mass of hydrogen is the smallest in comparison with other gases. In the subsequent stages of the development of science, many scientists worked with him, in particular Lavoisier, who called him "giving birth to water."

Characteristic by position in PSCE

Element opening periodic table DI Mendeleev, is hydrogen. The physical and chemical properties of the atom exhibit a certain duality, since hydrogen is simultaneously attributed to the first group, the main subgroup, if it behaves like a metal and donates a single electron in the process chemical reaction, and to the seventh - in the case of complete filling of the valence shell, that is, the reception of a negative particle, which characterizes it as similar to halogens.

Features of the electronic structure of the element

The properties of complex substances, of which it is part, and itself simple substance H 2 is primarily determined by the electronic configuration of the hydrogen. A particle has one electron with Z = (-1), which rotates in its orbit around a nucleus containing one proton with a unit mass and a positive charge (+1). Its electronic configuration is written as 1s 1, which means the presence of one negative particle on the very first and only s-orbital for the hydrogen.

When an electron is detached or given up, and the atom of this element has such a property that it makes it related to metals, a cation is obtained. Essentially, a hydrogen ion is a positive elementary particle. Therefore, the hydrogen deprived of an electron is simply called a proton.

Physical properties

In short, hydrogen is a colorless, slightly soluble gas with a relative atomic mass of 2, 14.5 times lighter than air, with a liquefaction temperature of -252.8 degrees Celsius.

It can be easily seen from experience that H 2 is the lightest. To do this, it is enough to fill three balls with various substances - hydrogen, carbon dioxide, ordinary air - and simultaneously release them from your hand. The one that is filled with CO 2 will reach the ground the fastest, after which the inflated air mixture will go down, and the one containing H 2 will rise to the ceiling.

The small mass and size of hydrogen particles justifies its ability to penetrate through various substances... On the example of the same ball, this is easy to be convinced of; in a couple of days it will deflate itself, since the gas will simply pass through the rubber. Also, hydrogen can accumulate in the structure of some metals (palladium or platinum), and evaporate from it when the temperature rises.

The property of low solubility of hydrogen is used in laboratory practice to isolate it by displacing hydrogen (the table below contains the main parameters) determine the scope of its application and methods of production.

Isotopic composition

Like many other representatives periodic system chemical elements, hydrogen has several natural isotopes, that is, atoms with the same number of protons in the nucleus, but a different number of neutrons - particles with zero charge and unit mass. Examples of atoms with a similar property are oxygen, carbon, chlorine, bromine and others, including radioactive ones.

The physical properties of hydrogen 1 H, the most common of the representatives of this group, differ significantly from the same characteristics of its counterparts. In particular, the characteristics of the substances in which they are included differ. So, there is ordinary and deuterated water, containing in its composition, instead of a hydrogen atom with a single proton, deuterium 2 H - its isotope with two elementary particles: positive and uncharged. This isotope is twice as heavy as conventional hydrogen, which explains the dramatic difference in the properties of the compounds they make up. In nature, deuterium occurs 3200 times less frequently than hydrogen. The third representative is tritium 3 H, in the nucleus it has two neutrons and one proton.

Methods for obtaining and isolating

Laboratory and industrial methods are quite different. So, in small quantities, gas is obtained mainly through reactions in which mineral substances are involved, and large-scale production in to a greater extent use organic synthesis.

The following chemical interactions are used in the laboratory:

In industrial interests, gas is obtained by such methods as:

1. Thermal decomposition of methane in the presence of a catalyst to its constituent simple substances (350 degrees reaches the value of such an indicator as temperature) - hydrogen H 2 and carbon C.
2. Passing vaporous water through coke at 1000 degrees Celsius to form carbon dioxide CO 2 and H 2 (the most common method).
3. Conversion of gaseous methane on a nickel catalyst at temperatures reaching 800 degrees.
4. Hydrogen is a by-product of the electrolysis of aqueous solutions of potassium or sodium chloride.

Chemical interactions: general provisions

The physical properties of hydrogen largely explain its behavior in reaction processes with this or that compound. The valency of hydrogen is 1, since it is located in the first group in the periodic table, and the oxidation state is different. In all compounds, except for hydrides, hydrogen in s.r. = (1+), in molecules of the type XH, XH 2, XH 3 - (1-).

The hydrogen gas molecule, formed by creating a generalized electron pair, consists of two atoms and is quite stable energetically, which is why it is somewhat inert under normal conditions and enters into a reaction when normal conditions change. Depending on the oxidation state of hydrogen in the composition of other substances, it can act as both an oxidizing agent and a reducing agent.

Substances with which it reacts and which forms hydrogen

Elemental interactions with the formation of complex substances (often at elevated temperatures):

1. Alkaline and alkaline earth metal+ hydrogen = hydride.
2. Halogen + H 2 = hydrogen halide.
3. Sulfur + hydrogen = hydrogen sulfide.
4. Oxygen + H 2 = water.
5. Carbon + hydrogen = methane.
6. Nitrogen + H 2 = ammonia.

Interaction with complex substances:

1. Production of synthesis gas from carbon monoxide and hydrogen.
2. Reduction of metals from their oxides using Н 2.
3. Hydrogen saturation of unsaturated aliphatic hydrocarbons.

Hydrogen bond

The physical properties of hydrogen are such that, being in conjunction with an electronegative element, it allows it to form a special type of bond with the same atom from neighboring molecules that have lone electron pairs (for example, oxygen, nitrogen and fluorine). The clearest example, on which it is better to consider such a phenomenon, is water. It can be said to be stitched with hydrogen bonds, which are weaker than covalent or ionic ones, but due to the fact that there are many of them, they have a significant effect on the properties of a substance. Essentially, hydrogen bonding is an electrostatic interaction that binds water molecules into dimers and polymers, justifying its high boiling point.

Hydrogen in mineral compounds

All include a proton - a cation of an atom such as hydrogen. A substance whose acidic residue has an oxidation state greater than (-1) is called a polybasic compound. It contains several hydrogen atoms, which makes dissociation into aqueous solutions multistage. Each subsequent proton is detached from the remainder of the acid more and more difficult. Its acidity is determined by the quantitative content of hydrogen in the medium.

Application in human activities

Cylinders with a substance, as well as containers with other liquefied gases, for example oxygen, have a specific appearance... They are painted a dark green color with a bright red inscription "Hydrogen". Gas is pumped into a cylinder at a pressure of about 150 atmospheres. The physical properties of hydrogen, in particular the lightness of the gaseous aggregate state, are used to fill balloons, balloons, etc., in a mixture with helium.

Hydrogen, the physical and chemical properties of which people learned to use many years ago, is currently used in many industries. Most of it goes to the production of ammonia. Hydrogen also participates in (hafnium, germanium, gallium, silicon, molybdenum, tungsten, zirconium and others) from oxides, acting in the reaction as a reducing agent, hydrocyanic and hydrochloric acids, as well as an artificial liquid fuel. The food industry uses it to convert vegetable oils into solid fats.

Determined the chemical properties and use of hydrogen in various processes of hydrogenation and hydrogenation of fats, coal, hydrocarbons, oils and fuel oil. It is used to produce precious stones, incandescent lamps, forge and weld metal products under the influence of an oxygen-hydrogen flame.

Generalizing scheme "HYDROGEN"

a) Position in the PSKhE

• serial number №1
• period 1
• group I (main subgroup "A")
• relative mass Ar (H) = 1
• Latin name Hydrogenium (water-giving birth)

b) The abundance of hydrogen in nature

c) The valence of hydrogen in compounds

II... Hydrogen is a simple substance (H 2)

Receiving

Finding 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 the number of atoms. Hydrogen is a 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 organisms of animals and plants (that is, in the composition of proteins, nucleic acids , fats, carbohydrates and others). In a free state, Hydrogen is extremely rare; it is contained in small quantities in volcanic and other natural gases. Trace 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 flux of protons forms the inner ("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, and radicals. In the form of a flux of protons, Hydrogen is part of the corpuscular radiation of the Sun and cosmic rays.

There are three isotopes of hydrogen:
a) light hydrogen - protium,
b) heavy hydrogen - deuterium (D),
c) superheavy hydrogen - tritium (T).

Tritium is an unstable (radioactive) isotope; therefore, it practically does not occur in nature. Deuterium is stable, but very little of it: 0.015% (of the mass of all terrestrial hydrogen).

Hydrogen valence in compounds

In compounds, hydrogen exhibits valence I.

Physical properties of hydrogen

A simple substance hydrogen (Н 2) is a gas, lighter than air, colorless, odorless, tasteless, bale = - 253 0 С, hydrogen is insoluble in water, combustible. Hydrogen can be collected by displacing air from a test tube or water. In this case, the tube must be turned upside down.

Hydrogen production

In the laboratory, hydrogen is obtained as a result of the reaction

Zn + H 2 SO 4 = ZnSO 4 + H 2.

Iron, aluminum and some other metals can be used instead of zinc, and some other dilute acids can be used instead of sulfuric acid. The resulting hydrogen is collected in a test tube by displacement of water (see Fig. 10.2 b) or simply in an inverted flask (Fig. 10.2 a).

In industry, hydrogen is obtained in large quantities from natural gas (mainly methane) by its interaction with water vapor at 800 ° C in the presence of a nickel catalyst:

CH 4 + 2H 2 O = 4H 2 + CO 2 (t, Ni)

or coal is treated at high temperature with water vapor:

2H 2 O + C = 2H 2 + CO 2. (t)

Pure hydrogen is obtained from water by decomposing it electric shock(subjecting to electrolysis):

2H 2 O = 2H 2 + O 2 (electrolysis).

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 a pure state, began to study it and described its properties.

This is the story of the discovery of hydrogen. In the course of experiments, the researcher determined that it is a combustible gas, the combustion of which in air gives water. This led to the determination of the qualitative composition of the water.

What is hydrogen

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

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

Characterization of hydrogen

N. Mendeleev assigned the designation hydrogen to this chemical element the first serial number, 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 H 2 is 2 amu. e. Molar mass numerically equal to it.

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

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

Physical properties

Under normal conditions, a simple substance hydrogen in the form of diatomic molecules is a gas, colorless, tasteless and odorless. Let's slightly dissolve in water and other solvents.

The crystallization temperature is 259.2 o C, the boiling point is 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 required to purify hydrogen from gaseous impurities. Under n. at. hydrogen has a density of 0.09 kg / m3.

Is it possible to convert 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.

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

Chemical properties

V chemical interaction both simple and complex substances enter with hydrogen. But the low activity of hydrogen must be increased by creating appropriate conditions - by raising the temperature, using catalysts, etc.

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

If you ignite pure hydrogen at the end of the gas outlet tube in the air, it will burn evenly, but barely noticeable. If the gas outlet tube is placed 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:

Combustion of water is accompanied by the release of a large amount of heat. It 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 proceeds in a similar way with the formation of hydrogen chloride.

For the interaction of nitrogen with hydrogen, it is required heat and increased 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, it is 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 and also in thermonuclear power.

Hydrogen also reacts with complex substances. For example, with copper (II) oxide, the 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 reddish-brown, and water droplets settle on the cold walls of the test tube.

During the reaction, hydrogen is oxidized to form water, and copper is reduced from oxide to a simple substance (Cu).

Areas of use

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

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

Scientists unanimously prophesy the palm in the energy sector for hydrogen fuel.

Getting in industry

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

Used for this purpose is the conversion of coke or methane with steam. Decomposition of methane at elevated temperatures also produces hydrogen. Liquefaction of coke oven gas by the fractional method is also used for industrial production of hydrogen.

Getting in the laboratory

The laboratory uses the Kipp apparatus to produce hydrogen.

The reagents are saline or sulphuric acid and zinc. The reaction produces hydrogen.

Finding hydrogen in nature

Hydrogen is the most common 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 matter, as well as in water, covering 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 combustible natural gases.

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

At the heart of the action is the most powerful hydrogen bomb lies the splitting of the lightest atom.