Hydrogen chemical properties obtaining application. Hydrogen, its special properties and reactions

Hydrogen (tracing paper from Latin: Latin Hydrogenium - hydro = "water", gen = "generating"; hydrogenium - "generating water"; denoted by the symbol H) is the first element of the periodic table of elements. Widely distributed in nature. The cation (and nucleus) of the most abundant hydrogen isotope, 1 H, is the proton. The properties of the 1 H nucleus make it possible to widely use NMR spectroscopy in analysis. organic matter.

Three isotopes of hydrogen have their own names: 1 H - protium (H), 2 H - deuterium (D) and 3 H - tritium (radioactive) (T).

Simple substance hydrogen - H 2 - light colorless gas. It is flammable and explosive when mixed with air or oxygen. Non-toxic. Let's dissolve in ethanol and a number of metals: iron, nickel, palladium, platinum.

History

The release of combustible gas during the interaction of acids and metals was observed in the XVI and XVII centuries at the dawn of the formation of chemistry as a science. Mikhail Vasilyevich Lomonosov also directly pointed to its separation, but already definitely realizing that it was not phlogiston. The English physicist and chemist Henry Cavendish investigated this gas in 1766 and called it "combustible air." When burned, the "combustible air" produced water, but Cavendish's adherence to the phlogiston theory prevented him from drawing correct conclusions. The French chemist Antoine Lavoisier, together with the engineer J. Meunier, using special gas meters, in 1783 synthesized water, and then analyzed it, decomposing water vapor with hot iron. Thus, he established that "combustible air" is part of water and can be obtained from it.

origin of name

Lavoisier gave hydrogen the name hydrogène (from ancient Greek ὕδωρ - water and γεννάω - I give birth) - "giving birth to water". The Russian name "hydrogen" was proposed by the chemist MF Soloviev in 1824 - by analogy with the "oxygen" of MV Lomonosov.

Prevalence

In the Universe
Hydrogen is the most abundant element in the universe. It accounts for about 92% of all atoms (8% are helium atoms, the share of all other elements taken together is less than 0.1%). Thus, hydrogen is the main component stars and interstellar gas. Under conditions of stellar temperatures (for example, the surface temperature of the Sun is ~ 6000 ° C), hydrogen exists in the form of plasma; in interstellar space, this element exists in the form of individual molecules, atoms and ions and can form molecular clouds that differ significantly in size, density and temperature.

Earth's crust and living organisms
The mass fraction of hydrogen in the earth's crust is 1% - this is the tenth most abundant element. However, its role in nature is determined not by mass, but by the number of atoms, the proportion of which among other elements is 17% (second place after oxygen, the proportion of atoms of which is ~ 52%). Therefore, the importance of hydrogen in the chemical processes taking place on Earth is almost as great as oxygen. Unlike oxygen, which exists on Earth in both bound and free states, practically all hydrogen on Earth is in the form of compounds; only a very small amount of hydrogen in the form simple substance contained in the atmosphere (0.00005% by volume).
Hydrogen is a part of almost all organic substances and is present in all living cells. In living cells, hydrogen accounts for almost 50% of the number of atoms.

Receiving

Industrial methods for obtaining simple substances depend on the form in which the corresponding element is found in nature, that is, what can be the raw materials for its production. So, oxygen, which is available in a free state, is obtained by a physical method - by separation from liquid air. Almost all hydrogen is in the form of compounds, therefore, to obtain it, they use chemical methods... In particular, decomposition reactions can be used. One of the methods for producing hydrogen is the reaction of water decomposition by electric current.
The main industrial method for producing hydrogen is the reaction of methane with water, which is part of natural gas. It is carried out at a high temperature:
CH 4 + 2H 2 O = CO 2 + 4H 2 −165 kJ

One of the laboratory methods for producing hydrogen, which is sometimes used in industry, is the decomposition of water with an electric current. Usually in the laboratory, hydrogen is produced by the interaction of zinc with hydrochloric acid.

DEFINITION

Hydrogen- the first element of the Periodic Table chemical elements DI. Mendeleev. Symbol - N.

Atomic mass - 1 amu The hydrogen molecule is diatomic - Н 2.

Electronic configuration hydrogen atom - 1s 1. Hydrogen belongs to the s-element family. In its compounds, it exhibits oxidation states -1, 0, +1. Natural hydrogen consists of two stable isotopes - protium 1 H (99.98%) and deuterium 2 H (D) (0.015%) - and the radioactive isotope tritium 3 H (T) (trace amounts, half-life - 12.5 years) ...

Chemical properties of hydrogen

At normal conditions molecular hydrogen exhibits a relatively low reactivity, which is explained by the high strength of bonds in the molecule. When heated, it interacts with almost all simple substances, formed elements main subgroups (except for noble gases, B, Si, P, Al). IN chemical reactions can act both as a reducing agent (more often) and as an oxidizing agent (less often).

Hydrogen exhibits reducing agent properties(Н 2 0 -2е → 2Н +) in the following reactions:

1. Reactions of interaction with simple substances - non-metals. Hydrogen reacts with halogens, moreover, the reaction of interaction with fluorine under normal conditions, in the dark, with an explosion, with chlorine - under illumination (or UV irradiation) by a chain mechanism, with bromine and iodine only when heated; oxygen(a mixture of oxygen and hydrogen in a volume ratio of 2: 1 is called "oxyhydrogen gas"), gray, nitrogen and carbon:

H 2 + Hal 2 = 2HHal;

2H 2 + O 2 = 2H 2 O + Q (t);

H 2 + S = H 2 S (t = 150 - 300C);

3H 2 + N 2 ↔ 2NH 3 (t = 500C, p, kat = Fe, Pt);

2H 2 + C ↔ CH 4 (t, p, kat).

2. Reactions of interaction with complex substances. Hydrogen reacts with oxides of low-activity metals, and it is able to reduce only metals that are in the row of activity to the right of zinc:

CuO + H 2 = Cu + H 2 O (t);

Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O (t);

WO 3 + 3H 2 = W + 3H 2 O (t).

Hydrogen reacts with oxides of non-metals:

H 2 + CO 2 ↔ CO + H 2 O (t);

2H 2 + CO ↔ CH 3 OH (t = 300C, p = 250 - 300 atm., Kat = ZnO, Cr 2 O 3).

Hydrogen enters into hydrogenation reactions with organic compounds of the class of cycloalkanes, alkenes, arenes, aldehydes and ketones, etc. All these reactions are carried out under heating, under pressure, platinum or nickel are used as catalysts:

CH 2 = CH 2 + H 2 ↔ CH 3 -CH 3;

C 6 H 6 + 3H 2 ↔ C 6 H 12;

C 3 H 6 + H 2 ↔ C 3 H 8;

CH 3 CHO + H 2 ↔ CH 3 —CH 2 —OH;

CH 3 -CO-CH 3 + H 2 ↔ CH 3 -CH (OH) -CH 3.

Hydrogen as an oxidizing agent(Н 2 + 2е → 2Н -) acts in reactions of interaction with alkali and alkaline earth metals. In this case, hydrides are formed - crystalline ionic compounds in which hydrogen exhibits an oxidation state of -1.

2Na + H 2 ↔ 2NaH (t, p).

Ca + H 2 ↔ CaH 2 (t, p).

Physical properties of hydrogen

Hydrogen is a light, colorless gas, odorless, density at normal conditions. - 0.09 g / l, 14.5 times lighter than air, t bale = -252.8 C, t pl = - 259.2 C. Hydrogen is poorly soluble in water and organic solvents, well soluble in some metals: nickel, palladium, platinum.

According to modern cosmochemistry, hydrogen is the most abundant element in the Universe. The main form of existence of hydrogen in outer space is individual atoms. In terms of abundance on Earth, hydrogen ranks 9th among all elements. The main amount of hydrogen on Earth is in a bound state - in the composition of water, oil, natural gas, coal etc. In the form of a simple substance, hydrogen is rare - in the composition of volcanic gases.

Hydrogen production

There are laboratory and industrial methods for producing hydrogen. Laboratory methods include the interaction of metals with acids (1), as well as the interaction of aluminum with aqueous solutions of alkalis (2). Among the industrial methods for producing hydrogen, electrolysis plays an important role. aqueous solutions alkalis and salts (3) and methane conversion (4):

Zn + 2HCl = ZnCl 2 + H 2 (1);

2Al + 2NaOH + 6H 2 O = 2Na +3 H 2 (2);

2NaCl + 2H 2 O = H 2 + Cl 2 + 2NaOH (3);

CH 4 + H 2 O ↔ CO + H 2 (4).

Examples of problem solving

EXAMPLE 1

The task	When 23.8 g of metallic tin reacted with an excess of hydrochloric acid, hydrogen was evolved, in an amount sufficient to obtain 12.8 g of metallic copper. Determine the oxidation state of tin in the resulting compound.
Solution	Based on the electronic structure of the tin atom (… 5s 2 5p 2), it can be concluded that tin is characterized by two oxidation states - +2, +4. Based on this, we will compose the equations of possible reactions: Sn + 2HCl = H 2 + SnCl 2 (1); Sn + 4HCl = 2H 2 + SnCl 4 (2); CuO + H 2 = Cu + H 2 O (3). Let's find the amount of copper substance: v (Cu) = m (Cu) / M (Cu) = 12.8 / 64 = 0.2 mol. According to equation 3, the amount of hydrogen is: v (H 2) = v (Cu) = 0.2 mol. Knowing the mass of tin, we find its amount of substance: v (Sn) = m (Sn) / M (Sn) = 23.8 / 119 = 0.2 mol. Let us compare the amounts of the substance of tin and hydrogen according to equations 1 and 2 and according to the condition of the problem: v 1 (Sn): v 1 (H 2) = 1: 1 (equation 1); v 2 (Sn): v 2 (H 2) = 1: 2 (equation 2); v (Sn): v (H 2) = 0.2: 0.2 = 1: 1 (problem condition). Therefore, tin reacts with hydrochloric acid according to equation 1 and the oxidation state of tin is +2.
Answer	The oxidation state of tin is +2.

EXAMPLE 2

The task	The gas released by the action of 2.0 g of zinc per 18.7 ml of 14.6% hydrochloric acid (solution density 1.07 g / ml) was passed while heating over 4.0 g of copper (II) oxide. What is the mass of the resulting solid mixture?
Solution	When zinc acts on hydrochloric acid, hydrogen is released: Zn + 2HCl = ZnCl 2 + H 2 (1), which, when heated, reduces copper (II) oxide to copper (2): CuO + H 2 = Cu + H 2 O. Let's find the amount of substances in the first reaction: m (solution HCl) = 18.7. 1.07 = 20.0 g; m (HCl) = 20.0. 0.146 = 2.92 g; v (HCl) = 2.92 / 36.5 = 0.08 mol; v (Zn) = 2.0 / 65 = 0.031 mol. Zinc is in short supply, so the amount of released hydrogen is equal to: v (H 2) = v (Zn) = 0.031 mol. In the second reaction, hydrogen is in short supply, because: v (CuO) = 4.0 / 80 = 0.05 mol. As a result of the reaction, 0.031 mol of CuO will turn into 0.031 mol of Cu, and the weight loss will be: m (CuO) - m (Cu) = 0.031 × 80 - 0.031 × 64 = 0.50 g. The mass of the solid mixture of CuO with Cu after passing hydrogen will be: 4.0-0.5 = 3.5 g.
Answer	The mass of the solid mixture of CuO and Cu is 3.5 g.

IN periodic system has its own definite place of position, which reflects the properties shown 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 donation of an electron, it has a free orbital, which takes part in the formation of chemical bonds by the 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. Thanks to a 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 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 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 conversion 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 be used only for aqueous solutions of various salts, since the melts do not lead to the discharge of water at the cathode.

Laboratory methods for producing 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 as, for example, carbon dioxide... This is hydrogen, it is much lighter than air. It quickly evaporates, and in large quantities explodes 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 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 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.

Exactly at aquatic environment almost everything happens chemical processes... 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 essential 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, therefore, it is not recommended by specialists for these purposes.

Hydrogen - inorganic substance, the first and lightest element of the periodic table. It is designated by the letter H (Hydrogenium), translated from Greek as "giving birth to water."

There are three stable hydrogen atoms in nature:
... protium - the standard version of the atom, consisting of a proton and an electron;
... deuterium - consists of a proton, neutron and electron;
... tritium - there is a proton and two neutrons in the nucleus.

There is a lot of hydrogen on Earth. Based on the number of atoms, it is about 17%. Only oxygen is more - about 52%. And this is only in the earth's crust and atmosphere - scientists do not know how much of it is in the mantle and core of the planet. On Earth, hydrogen is predominantly in a bound state. It is part of water, all living cells, natural gas, oil, coal, some rocks and minerals. In an unbound state, it can be found in volcanic gases, in organic decomposition products.

Properties

The lightest gas. Has no color, taste or smell. It is poorly soluble in water, well - in ethanol, in many metals, for example, in iron, titanium, palladium - 850 volumes of H2 can be dissolved in one volume of palladium. Does not dissolve in silver. Heat conducts best of all gases. With strong cooling, it transforms into a very mobile, flowing colorless liquid, and then into a solid snow-like substance. Interesting that liquid state the element remains in a very narrow temperature range: from -252.76 to -259.2 ° C. It is assumed that solid hydrogen at gigantic pressures of hundreds of thousands of atmospheres will acquire metallic properties. At high temperatures ah the substance penetrates through the smallest pores of metals and alloys.

Hydrogen is an important nutrient. Forms water, is found in all living tissues, in amino and nucleic acids, proteins, lipids, fats, carbohydrates.

From the point of view of chemistry, hydrogen has a unique feature - it belongs to two groups of the periodic table at once: alkali metals and halogens. As an alkali metal, it exhibits strong reducing properties. Reacts with fluorine under normal conditions, with chlorine - under the influence of light, with other non-metals - only when heated or in the presence of catalysts. Reacts with oxygen, nitrogen, sulfur, carbon, halogens, carbon monoxide and others. Forms such important compounds as ammonia, hydrogen sulfide, hydrocarbons, alcohols, hydrogen fluoride (hydrofluoric acid) and hydrogen chloride (hydrochloric acid). When interacting with metal oxides and halides, it reduces them to metals; this property is used in metallurgy.

As a halogen, H2 exhibits oxidizing properties when interacting with metals.

There is 88.6% hydrogen in the Universe. Most of it is contained in stars and interstellar gas.

Because of their lightness, the molecules of matter move at tremendous speeds comparable to the second cosmic speed. Due to this, its thermal conductivity exceeds the thermal conductivity of air by 7.3 times. From the upper parts of the atmosphere, H2 molecules easily fly into space. Thus, our planet is losing 3 kg of hydrogen every second.

Safety engineering

Hydrogen is non-toxic, but fire and explosive. A mixture with air (oxyhydrogen gas) explodes easily at the slightest spark. The hydrogen itself burns. This should be taken into account when receiving it for laboratory needs or when conducting experiments in the course of which hydrogen is released.

Spilling liquid hydrogen on your skin can result in severe frostbite.

Application

In the chemical industry, using H2, ammonia, alcohols, hydrochloric acid, soap, polymers, artificial fuel, and many organic substances are produced.
... In the oil refining industry - for obtaining various derivatives from oil and oil residues (diesel fuel, lubricating oils, gasoline, liquefied gases, etc.); for cleaning petroleum products, lubricating oils.
... In the food industry: in the manufacture of solid margarines by hydrogenation from vegetable oils; used as a gas for packaging some products (additive E949).
... In metallurgy in the processes of obtaining metals and alloys. For atomic-hydrogen (flame temperature reaches +4000 ° C) and oxygen-hydrogen (up to +2800 ° C) cutting and welding of heat-resistant steels and alloys.
... In meteorology, air balloons and balloons are filled with matter.
... As fuel for rockets.
... As a cooler for large power generators.
... In the glass industry for melting quartz glass in a high temperature flame.
... In gas chromatography; for filling (liquid H2) bubble chambers.
... As a refrigerant in cryogenic vacuum pumps.
... Deuterium and tritium are used in nuclear energy and military affairs.

Hydrogen. Properties, receipt, application.

Historical reference

Hydrogen is the first element of PSCHE D.I. Mendeleev.

The Russian name for hydrogen indicates that it "gives birth to water"; Latin " hydrogenium " means the same thing.

For the first time, the release of combustible gas during the interaction of certain metals with acids was observed by Robert Boyle and his contemporaries in the first half of the 16th century.

But hydrogen was discovered only in 1766 by the English chemist Henry Cavendish, who established that when metals interact with dilute acids, a kind of "combustible air" is released. Observing the combustion of hydrogen in air, Cavendish found that the result is water. This was in 1782.

In 1783, the French chemist Antoine-Laurent Lavoisier isolated hydrogen by decomposing water with a red-hot iron. In 1789, hydrogen was released by the decomposition of water under the action of an electric current.

Prevalence in nature

Hydrogen is the main element of the cosmos. For example, the Sun is 70% of its mass hydrogen. There are several tens of thousands of times more hydrogen atoms in the Universe than all the atoms of all metals taken together.

In the earth's atmosphere, there is also a little hydrogen in the form of a simple substance - a gas of the composition H 2. Hydrogen is much lighter than air, and therefore it is found in upper layers atmosphere.

But there is much more bound hydrogen on Earth: after all, it is part of water, the most common complex substance on our planet. Hydrogen bound into molecules contains both oil and natural gas, many minerals and rocks. Hydrogen is part of all organic substances.

Characterization of the element hydrogen.

Hydrogen has a dual nature, for this reason, in some cases, hydrogen is placed in the subgroup of alkali metals, and in others, in the subgroup of halogens.

• 
  Electronic configuration 1s 1 . A hydrogen atom is made up of one proton and one electron.
• 
  The hydrogen atom is able to lose an electron and turn into an H + cation, and in this it is similar to alkali metals.
• 
  The hydrogen atom can also attach an electron, forming the anion H -, in this respect hydrogen is similar to halogens.
• 
  In compounds it is always monovalent
• 
  CO: +1 and -1.

Physical properties of hydrogen

Hydrogen is a gas, colorless, tasteless and odorless. 14.5 times lighter than air. Let's slightly dissolve in water. Has a high thermal conductivity. At t = –253 ° С it liquefies, at t = –259 ° С it solidifies. Hydrogen molecules are so small that they can slowly diffuse through many materials - rubber, glass, metals, which is used to purify hydrogen from other gases.

There are 3 known isotopes of hydrogen: - protium, - deuterium, - tritium. The main part of natural hydrogen is protium. Deuterium is a part of heavy water, which is enriched surface waters ocean. Tritium is a radioactive isotope.

Chemical properties hydrogen

Hydrogen is a non-metal, has molecular structure... A hydrogen molecule consists of two atoms linked together by a covalent non-polar bond. The binding energy in a hydrogen molecule is 436 kJ / mol, which explains the low reactivity of molecular hydrogen.

1. 
   Interaction with halogens. At normal temperatures, hydrogen reacts only with fluorine:

H 2 + F 2 = 2HF.

With chlorine - only in the light, forming hydrogen chloride, with bromine, the reaction proceeds less vigorously, with iodine it does not go to the end even at high temperatures.

1. 
   Interaction with oxygen - on heating, on ignition, the reaction proceeds with an explosion: 2H 2 + O 2 = 2H 2 O.

Hydrogen burns in oxygen with the release of a large amount of heat. The temperature of the hydrogen-oxygen flame is 2800 ° C.

A mixture of 1 part oxygen and 2 parts hydrogen - " dangerous mix"Is the most explosive.

1. 
   Interaction with sulfur - when heated H 2 + S = H 2 S.
2. 
   Interaction with nitrogen. When heated, high pressure and in the presence of a catalyst:

3H 2 + N 2 = 2NH 3.

1. 
   Interaction with nitric oxide (II). Used in purification systems during production nitric acid: 2NO + 2H 2 = N 2 + 2H 2 O.
2. 
   Interaction with metal oxides. Hydrogen is a good reducing agent, it reduces many metals from their oxides: CuO + H 2 = Cu + H 2 O.
3. 
   Atomic hydrogen is a strong reducing agent. It is formed from molecular in an electric discharge under conditions low pressure... Possesses high restorative activity hydrogen at the time of release formed during the reduction of a metal with an acid.
4. 
   Interaction with active metals ... At high temperatures, it combines with alkali and alkaline earth metals to form white crystalline substances- metal hydrides, exhibiting the properties of an oxidizing agent: 2Na + H 2 = 2NaH;

Ca + H 2 = CaH 2.

Hydrogen production

In the laboratory:

1. 
   Interaction of metal with dilute solutions of sulfuric and hydrochloric acids,

Zn + 2HCl = ZnCl 2 + H 2.

1. 
   Interaction of aluminum or silicon with aqueous solutions of alkalis:

2Al + 2NaOH + 10H 2 O = 2Na + 3H 2;

Si + 2NaOH + H 2 O = Na 2 SiO 3 + 2H 2.

In industry:

1. 
   Electrolysis of aqueous solutions of sodium and potassium chlorides or electrolysis of water in the presence of hydroxides:

2NaCl + 2H 2 O = H 2 + Cl 2 + 2NaOH;

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

1. 
   Conversion method. First, water gas is obtained by passing water vapor through hot coke at 1000 ° C:

C + H 2 O = CO + H 2.

Then carbon monoxide (II) is oxidized to carbon monoxide (IV) by passing a mixture of water gas with excess water vapor over a Fe 2 O 3 catalyst heated to 400–450 ° C:

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

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

1. 
   Methane conversion: CH 4 + H 2 O = CO + 3H 2.

This reaction takes place in the presence of a nickel catalyst at 800 ° С.

1. 
   Thermal decomposition of methane at 1200 ° C: CH 4 = C + 2H 2.
2. 
   Deep cooling (down to -196 ° С) of coke oven gas. At this temperature, all gaseous substances, except hydrogen, condense.

Application of hydrogen

The use of hydrogen is based on its physical and chemical properties:

• 
  as a light gas, it is used to fill balloons (mixed with helium);
• 
  oxygen-hydrogen flame is used to obtain high temperatures when welding metals;
• 
  as a reducing agent used to obtain metals (molybdenum, tungsten, etc.) from their oxides;
• 
  for the production of ammonia and artificial liquid fuel, for the hydrogenation of fats.