Why water does not burn, although it consists of combustible substances (hydrogen and oxygen). Hydrogen

Industrial methods of obtaining simple substances depend on what form the corresponding element is in nature, that is, that may be raw materials for its preparation. Thus, oxygen existing in free state is obtained by a physical method - separation from liquid air. Hydrogen is almost entirely in the form of compounds, therefore, chemical methods are used to obtain it. In particular, decomposition reactions can be used. One of the methods of obtaining hydrogen is the reaction of water decomposition by electric shock.

The main industrial method of obtaining hydrogen is a reaction with water of methane, which is part of natural gas. It is carried out at high temperatures (it is easy to make sure that when methane passes, even through boiling water, no reaction occurs):

CH 4 + 2N 2 0 \u003d CO 2 + 4N 2 - 165 kJ

In the laboratory, not necessarily natural raw materials are used to obtain simple substances, but choose the source substances, of which it is easier to select the necessary substance. For example, in the laboratory oxygen is not obtained from the air. The same applies to the preparation of hydrogen. One of the laboratory methods for producing hydrogen, which is sometimes used in the industry - expansion of water with electric stroke.

Usually, hydrogen laboratories are obtained by the interaction of zinc with hydrochloric acid.

In industry

1.Electrolysis of aqueous salts:

2NACL + 2H 2 O → H 2 + 2NAOH + CL 2

2.Transmission of water vapor over hot coke at a temperature of about 1000 ° C:

H 2 O + C ⇄ H 2 + CO

3.From natural gas.

Conversion by water steam: CH 4 + H 2 O ⇄ CO + 3H 2 (1000 ° C) Catalytic oxidation with oxygen: 2CH 4 + O 2 ⇄ 2CO + 4H 2

4. Crequen and reforming hydrocarbons in the process of oil refining.

In the laboratory

1.The effect of diluted acids to metals. To carry out such a reaction, zinc and hydrochloric acid are most often used:

Zn + 2hcl → ZnCl 2 + H 2

2.Calcium interaction with water:

CA + 2H 2 O → Ca (OH) 2 + H 2

3.Hydrolysis hydrides:

NAH + H 2 O → NaOH + H 2

4.Action alkalis for zinc or aluminum:

2AL + 2NAOH + 6H 2 O → 2NA + 3H 2 Zn + 2KOH + 2H 2 O → K 2 + H 2

5.With the help of electrolysis. With the electrolysis of the aqueous solutions of alkali or acids on the cathode, hydrogen is released, for example:

2H 3 O + + 2e - → H 2 + 2H 2 O

• Bioreactor for hydrogen production

Physical properties

Gaseous hydrogen can exist in two forms (modifications) - in the form of ortho and para-hydrogen.

In the orthodorod molecule (so pl. -259.10 ° C, t. Kip. -252.56 ° C) nuclear spins are directed equally (parallel), and at Paravodorod (m. Pl. -259,32 ° C, t . Kip. -252,89 ° C) - opposite to each other (anti-parallel).

It is possible to split alto hydrogen altropy forms at an active angle at liquid nitrogen temperature. At very low temperatures, the equilibrium between the orthopomy and the waterproof is almost aimed towards the latter. At 80 to the form ratio of approximately 1: 1. The desorbed paralodine under heating turns into an orthodoxide up to the formation of equilibrium at room temperature of the mixture (ortho-steam: 75:25). Without a catalyst, the transformation occurs slowly, which makes it possible to study the properties of individual allotropic forms. Hydrogen molecule Dvkhatomna - H₂. Under normal conditions, it is gas without color, smell and taste. Hydrogen is the easiest gas, its density is many times less than air density. Obviously, the less weight of molecules, the higher their speed at the same temperature. As the easiest, hydrogen molecules are moving faster than molecules of any other gas and thus faster can transmit heat from one body to another. It follows that hydrogen has the highest thermal conductivity among gaseous substances. Its thermal conductivity is approximately seven times higher than thermal conductivity of air.

Chemical properties

Hydrogen molecules H₂ are quite durable, and in order for hydrogen to enter into the reaction, a large energy should be spent: H 2 \u003d 2N - 432 kJ so, at normal temperatures, hydrogen reacts with very active metals, for example with calcium, forming calcium hydride: CA + H 2 \u003d SAN 2 and with a single non-metallol - fluorine, forming fluorine hydrogen: F 2 + H 2 \u003d 2HF with most metals and non-metals hydrogen reacts at elevated temperatures or with a different effect, for example when lighting. It can "take away" oxygen from some oxides, for example: Cuo + H 2 \u003d Cu + H 2 0 The recorded equation reflects the recovery reaction. Recovery reactions are called processes, as a result of which oxygen is taken from the compound; Oxygen consistent substances are called reducing agents (at the same time they themselves are oxidized). Next, another definition of the concepts of "oxidation" and "recovery" will be given. And this definition, historically first, retains the meaning and now, especially in organic chemistry. Recovery response is the opposite of the oxidation reaction. Both of these reactions always proceed at the same time as one process: when oxidizing (recovery) of a single substance, it is defined simultaneously recovery (oxidation) of another.

N 2 + 3H 2 → 2 NH 3

With halogens forms halogen breeding:

F 2 + H 2 → 2 HF, the reaction proceeds with an explosion in the dark and at any temperature, CL 2 + H 2 → 2 HCl, the reaction proceeds with an explosion, only in the light.

With soot interact with strong heating:

C + 2H 2 → CH 4

Interaction with alkaline and lump-earth metals

Hydrogen forms with active metals hydrides:

Na + H 2 → 2 NAH CA + H 2 → CAH 2 MG + H 2 → MGH 2

Hydrides - saline, solids, easily hydrolyzed:

CAH 2 + 2H 2 O → CA (OH) 2 + 2H 2

Interaction with metals oxides (usually D-elements)

Oxides are restored to metals:

Cuo + H 2 → Cu + H 2 O FE 2 O 3 + 3H 2 → 2 Fe + 3H 2 O WO 3 + 3H 2 → W + 3H 2 O

Hydrogenation of organic compounds

Under the action of hydrogen on unsaturated hydrocarbons in the presence of a nickel catalyst and an elevated temperature, a reaction occurs hydrogenation:

CH 2 \u003d CH 2 + H 2 → CH 3 -CH 3

Hydrogen restores aldehydes to alcohols:

CH 3 CHO + H 2 → C 2 H 5 OH.

Geochemistry of hydrogen

Hydrogen is the main building material of the universe. This is the most common element, and all the elements are formed from it as a result of thermonuclear and nuclear reactions.

The free hydrogen H 2 is relatively rarely found in the earth's gases, but in the form of water it takes extremely important participation in geochemical processes.

The hydrogen minerals can be included in the form of ammonium ion, hydroxyl ion and crystalline water.

In the atmosphere, hydrogen is continuously formed as a result of water decomposition by solar radiation. It migrates to the upper layers of the atmosphere and disappears into space.

Application

• Hydrogen energy

Atomic hydrogen is used for atomic hydrogen welding.

In the food industry, hydrogen is registered as a food additive E949.like packaging gas.

Features of circulation

Hydrogen at a mixture with air forms an explosive mixture - the so-called rat gas. This gas has the greatest explosiveness with a volume of hydrogen and oxygen 2: 1, or hydrogen and air approximately 2: 5, since in the air of oxygen contains approximately 21%. Also hydrogen is fire hazardous. Liquid hydrogen when popping on the skin can cause severe frostbite.

Explosive concentrations of hydrogen with oxygen arise from 4% to 96% of volumetric. With a mixture with air from 4% to 75 (74)% of volumetric.

Using hydrogen

In the chemical industry, hydrogen is used in the production of ammonia, soap and plastics. In the food industry with hydrogen from liquid vegetable oils make margarine. Hydrogen is very lung and in the air always rises up. Once upon agencies and balloons were filled with hydrogen. But in the 30s. XX century There were several terrible catastrophes when the airships exploded and burned. Nowadays, the airships are filled with gas helium. Hydrogen is also used as rocket fuel. Someday hydrogen may be widely used as fuel for passenger and trucks. Hydrogen engines do not pollute the environment and allocate only water vapor (though, the very obtaining hydrogen leads to some environmental pollution). Our sun mainly consists of hydrogen. Solar heat and light is the result of nuclear energy release during the merger of hydrogen nuclei.

Using hydrogen as fuel (economic efficiency)

The most important characteristic of the substances used as fuel is their heat of combustion. From the course of general chemistry it is known that the reaction of the interaction of hydrogen with oxygen occurs with heat release. If you take 1 mol H 2 (2 g) and 0.5 mol O 2 (16 g) under standard conditions and excite the reaction, then according to the equation

H 2 + 0.5 o 2 \u003d H 2 o

after completion of the reaction, 1 mol h 2 o (18 g) is formed with an energy release of 285.8 kJ / mol (for comparison: the heat of the combustion of acetylene is 1300 kJ / mol, propane - 2200 kJ / mol). 1 m³ of hydrogen weighs 89.8 g (44.9 mol). Therefore, 12832.4 kJ of energy will be spent to obtain 1 m³ of hydrogen. Taking into account the fact that 1 kW · h \u003d 3600 kJ, we get 3.56 kWh of electricity. Knowing the tariff for 1 kW of electricity and the cost of 1 m³ of gas, it is possible to conclude about the feasibility of the transition to hydrogen fuel.

For example, the experimental model of Honda FCX 3 generations with a hydrogen tank 156 l (contains 3.12 kg of hydrogen under pressure of 25 MPa) 355 km drives. Accordingly, 123.8 kWh is obtained from 3.12 kg H2. At 100 km, energy consumption will be 36.97 kWh. Knowing the cost of electricity, the cost of gas or gasoline, their consumption for a car per 100 km is easy to calculate the negative economic effect of car transition to hydrogen fuel. Let's say (Russia 2008), 10 cents per kWh of electricity lead to the fact that 1 m³ of hydrogen leads to the price of 35.6 cents, and taking into account the efficiency of water decomposition of 40-45 cents, the same number of kWh · h from gasoline burning 12832,4kg / 42000kj / 0.7kg / l * 80tesunts / l \u003d 34 cents at retail prices, whereas for hydrogen, we calculated the perfect option, without taking into account the transportation, depreciation of equipment, etc. For methane with the combustion energy of about 39 MJ On m³ the result will be below two to four times due to the difference in price (1m³ for Ukraine costs $ 179, and for Europe $ 350). That is, an equivalent amount of methane will cost 10-20 cents.

However, we should not forget that when burning hydrogen, we obtain clean water from which it was mined. That is, we have renewable pplash Energy without harm to the environment, in contrast to gas or gasoline, which are primary energy sources.

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Hydrogen H is the most common element in the universe (about 75% by weight), on earth - the ninth prevalence. The most important natural compound of hydrogen is water.
Hydrogen ranks first in the periodic system (Z \u003d 1). It has the simplest structure of the atom: the atom core - 1 proton, is surrounded by an electron cloud consisting of 1 electron.
In some conditions, hydrogen exhibits metal properties (gives an electron), in others - non-metallic (receiving an electron).
In nature, there are hydrogen isotopes: 1N - dates (the core consists of one proton), 2N - deuterium (D - the kernel consists of one proton and one neutron), 3H - tritium (T - the core consists of one proton and two neutrons).

Simple substance hydrogen

The hydrogen molecule consists of two atoms, interconnected by a covalent non-polar bond.
Physical properties. Hydrogen is a colorless non-toxic gas without smell and taste. Hydrogen molecule is not polar. Therefore, the forces of intermolecular interaction in hydrogen gaseous hydrogen. This is manifested in low boiling temperatures (-252.6 0 ° C) and melting (-259.2 0 ° C).
Hydrogen is easier than air, D (by air) \u003d 0.069; Misnally dissolves in water (in 100 volumes of H2O, 2 volumes of H2 are dissolved). Therefore, hydrogen when obtaining it in the laboratory can be collected by the methods of extrusion of air or water.

Obtaining hydrogen

In the laboratory:

1. Equality of diluted acids to metals:
Zn + 2hcl → ZnCl 2 + H 2

2. Recovery of alkaline and sh-z water with water:
CA + 2H 2 O → Ca (OH) 2 + H 2

3. Hydrides hydrides: metal hydrides are easily decomposed with water to form appropriate alkali and hydrogen:
NAH + H 2 O → NaOH + H 2
SAH 2 + 2N 2 O \u003d CA (OH) 2 + 2N 2

4. Equality alkalis for zinc or aluminum or silicon:
2AL + 2NAOH + 6H 2 O → 2NA + 3H 2
Zn + 2KOH + 2H 2 O → K 2 + H 2
Si + 2NAOH + H 2 O → Na 2 SiO 3 + 2H 2

5. Electrolysis of water. To increase the electrical conductivity of water, electrolyte is added to it, for example NAO, H 2 SO 4 or Na 2 SO 4. On the cathode, 2 volume of hydrogen is formed, on the anode - 1 oxygen volume.
2H 2 O → 2H 2 + O 2

Industrial production of hydrogen

1. Conversion of methane with water vapor, NI 800 ° C (cheapest):
CH 4 + H 2 O → CO + 3 H 2
CO + H 2 O → CO 2 + H 2

In total:
CH 4 + 2 H 2 O → 4 H 2 + CO 2

2. Couples of water through hot coke at 1000 o C:
C + H 2 O → CO + H 2
CO + H 2 O → CO 2 + H 2

The resulting carbon oxide (IV) is absorbed by water, this method is obtained by 50% of industrial hydrogen.

3. Heating methane to 350 ° C in the presence of an iron or nickel catalyst:
SH 4 → C + 2N 2

4. Electrolysis of KCL or NaCl aqueous solutions, like a by-product:
2N 2 O + 2NACL → CL 2 + H 2 + 2NAOH

Chemical properties of hydrogen

• In compounds, hydrogen is always monovalent. It is characterized by the degree of oxidation +1, but in the hydrides of the metals it is equal to -1.
• The hydrogen molecule consists of two atoms. The emergence of communication between them is due to the formation of a generalized pair of electrons H: H or H 2
• Due to this generalization of electrons, the H 2 molecule is more energetically stable than its individual atoms. To break the molecules to atoms in 1 mol, it is necessary to spend the energy of 436 kJ: H 2 \u003d 2N, ΔH ° \u003d 436 kJ / mol
• This explains the relatively small activity of molecular hydrogen at normal temperature.
• With many non-metals, hydrogen forms gaseous compounds of type RN 4, RN 3, RN 2, RN.

1) with halogens forms halogen breeds:
H 2 + Cl 2 → 2NSL.
At the same time with fluorine, it explodes, with chlorine and bromom reacts only when lighting or heating, and with iodine only when heated.

2) with oxygen:
2N 2 + O 2 → 2N 2
With heat release. At normal temperatures, the reaction proceeds slowly, above 550 ° C - with an explosion. A mixture of 2 volumes H 2 and 1 volume of 2 is called the rat gas.

3) when heated, heavily reacts with gray (much more difficult with selenium and tellurium):
H 2 + S → H 2 S (hydrogen sulfide),

4) with nitrogen with the formation of ammonia only on the catalyst and at elevated temperatures and pressures:
ZN 2 + N 2 → 2NN 3

5) with carbon at high temperatures:
2N 2 + C → CH 4 (methane)

6) with alkaline and alkaline earth metals forms hydrides (hydrogen - oxidizing agent):
H 2 + 2LI → 2LIH
in the hydrides of metals, the hydrogen ion is charged negatively (degree of oxidation -1), that is, the hydride Na + H is built like a Na + Cl chloride -

With complicated substances:

7) with metals oxides (used to restore metals):
Cuo + H 2 → Cu + H 2 O
Fe 3 O 4 + 4H 2 → 3FE + 4N 2

8) with carbon oxide (II):
CO + 2H 2 → CH 3 OH
Synthesis - gas (a mixture of hydrogen and carbon monoxide) has an important practical value, the TC, depending on the temperature, pressure and catalyst, various organic compounds are formed, for example, it is nso, it is already 3 and others.

9) unsaturated hydrocarbons react with hydrogen, moving to saturated:
With N 2N + H 2 → C N 2N + 2.

Oxygen is the most common element on Earth. Together with nitrogen and insignificant number of other gases, free oxygen forms the atmosphere of the Earth. Its content in the air is 20.95% by volume or 23.15% by weight. In the earth's crust, 58% of atoms are atoms of bound oxygen (47% by weight). Oxygen is part of the water (reserves of bound oxygen in the hydrosphere are exceptionally large), rocks, many minerals and salts, contains in fats, proteins and carbohydrates, from which living organisms consist. Practically all free oxygen of the Earth arose and persisted as a result of the photosynthesis process.

Physical properties.

Oxygen - gas without color, taste and odor, a little heavier air. In the water, a small solvent (in 1 liter of water at 20 degrees, 31 ml of oxygen is dissolved), but still better than other atmospheric gases, therefore water is enriched with oxygen. The density of oxygen under normal conditions is 1.429g / l. At temperatures -183 0 C and a pressure of 101,325 kPa oxygen goes into a liquid state. Liquid oxygen has a bluish color, draws into a magnetic field, and at -218.7 ° C, forms blue crystals.

Natural oxygen has three isotop about 16, about 17, about 18.

Allotropy- the ability of the chemical element to exist in the form of two or several simple substances, differing only in the number of atoms in the molecule or the structure.

Ozone about 3 - exists in the upper layers of the atmosphere at an altitude of 20-25 km from the surface of the Earth and forms the so-called "ozone layer", which protects the Earth from the destructive ultraviolet radiation of the Sun; Pale violet, poisonous in large quantities with a specific, sharp, but pleasant smell. The melting point is - 192.7 0 s, the boiling point-111.9 0 C. In water, soluble is better than oxygen.

Ozone is a strong oxidizing agent. Its oxidative activity is based on the ability of the molecule to decompose with the release of atomic oxygen:

It oxidizes many simple and complex substances. With some metals, ozonides forms, for example, Potassia Ozonide:

K + O 3 \u003d KO 3

Ozone is obtained in special devices - ozonomators. In them, under the action of an electrical discharge, the conversion of molecular oxygen into ozone:

A similar reaction occurs under the action of thunderstorms.

The use of ozone is due to its strong oxidative properties: it is used to whiten the tissues, disinfection of drinking water, in medicine as a disinfectant.

Inhalation of ozone in large quantities is harmful: it is annoying the mucous membranes of the eyes and the respiratory organs.

Chemical properties.

In chemical reactions with atoms of other elements (except fluorine), oxygen exhibits exclusively oxidative properties

The most important chemical property is the ability to form oxides with almost all the elements. At the same time, with most substances, oxygen reacts directly, especially when heated.

As a result of these reactions, as a rule, oxides are formed, less often - peroxides:

2SA + O 2 \u003d 2SAO

2VA + O 2 \u003d 2VAO

2NA + O 2 \u003d Na 2 O 2

Oxygen does not interact directly with halogens, gold, platinum, their oxides are indirectly obtained. When sulfur heated, carbon, phosphorus burn in oxygen.

The interaction of oxygen with nitrogen begins only at a temperature of 1200 0 s or in an electric discharge:

N 2 + O 2 \u003d 2NO

With hydrogen oxygen forms water:

2N 2 + O 2 \u003d 2N 2

In the process of this reaction, a significant amount of heat is highlighted.

A mixture of two hydrogen volumes with one oxygen during the ignition explodes; It is called a rattled gas.

Many metals in contact with air oxygen are destroyed - corrosion. Some metals under normal conditions are oxidized only from the surface (for example, aluminum, chromium). The resulting oxide film prevents further interaction.

4Al + 3O 2 \u003d 2AL 2 O 3

Complicated substances under certain conditions also interact with oxygen. At the same time, oxides are formed, and in some cases - oxides and simple substances.

CH 4 + 2O 2 \u003d CO 2 + 2N 2

H 2 S + O 2 \u003d 2SO 2 + 2N 2

4NN 3 + ZO 2 \u003d 2N 2 + 6N 2

4CH 3 NH 2 + 9O 2 \u003d 4CO 2 + 2N 2 + 10H 2 O

When interacting with complex substances, oxygen acts as an oxidizing agent. On oxidative activity of oxygen, its important property is based - the ability to support combustionsubstances.

The oxygen with hydrogen also forms a compound - hydrogen peroxide H 2 O 2 is a colorless transparent liquid with a burning astringent taste, well soluble in water. In the chemical ratio of hydrogen peroxide is a very interesting connection. It is characterized by its low stability: when standing, slowly decomposes on water and oxygen:

H 2 O 2 \u003d H 2 O + O 2

Light, heating, alkali presence, contact with oxidizing agents or reducing agents accelerate the decomposition process. The degree of oxidation of oxygen in hydrogen peroxide \u003d - 1, i.e. It has an intermediate value between the degree of oxidation of oxygen in water (-2) and in molecular oxygen (0), so hydrogen peroxide exhibits redox duality. The oxidative properties of hydrogen peroxide are much stronger than reducing, and they appear in acidic, alkaline and neutral media.

H 2 O 2 + 2KI + H 2 SO 4 \u003d K 2 SO 4 + I 2 + 2H 2 O

In the periodic system, hydrogen is located in two absolutely opposite in their properties of groups of elements. This feature make it completely unique. Hydrogen is not simply an element or substance, but also is an integral part of many complex compounds, organogenic and biogenic element. Therefore, we consider its properties and characteristics in more detail.

The separation of fuel gas in the process of interaction between metals and acids was observed in the XVI century, that is, during the formation of chemistry as science. The famous English scientist Henry Cavendish explored the substance since 1766, and gave him the name "combustible air". When burning, this gas gave water. Unfortunately, the commitment of the scientist theory of phlogiston (hypothetical "hypothone of matter") prevented him to come to the right conclusions.

The French chemist and the naturalist A. Lavoisier, together with the engineer J. More and with the help of special gasometers in 1783, conducted a synthesis of water, and after and its analysis by decomposing water vapor hot iron. Thus, scientists were able to come to the right conclusions. They found that "combustible air" is not only part of the water, but can also be obtained from it.

In 1787, Lavoisier put forward the assumption that the gas under study is a simple substance and, accordingly, refers to the number of primary chemical elements. He called him Hydrogene (from the Greek Words of Hydor - Water + Gennao - God), i.e. "Horing Water".

The Russian name "Hydrogen" in 1824 proposed a Chemist M. Solovyov. The determination of the composition of water marked the end of the "Flogiston theory". At the junction of the XVIII and XIX centuries, it was found that the hydrogen atom is very light (compared to atoms of other elements) and its mass was adopted for the main unit of comparison of atomic masses, obtaining a value equal to 1.

Physical properties

Hydrogen is the easiest of all known science of substances (it is 14.4 times lighter than air), its density is 0.0899 g / l (1 atm, 0 ° C). This material melts (hardens) and boils (liquefied), respectively, at -259.1 ° C and -252.8 ° C (only helium has lower boiling and melting t °).

Critical temperature of hydrogen is extremely low (-240 ° C). For this reason, his liquefaction is a rather complicated and cost process. The critical pressure of the substance is 12.8 kgf / cm², and the critical density is 0.0312 g / cm³. Among all gases, hydrogen has the greatest thermal conductivity: at 1 atm and 0 ° C, it equals 0.174 W / (MHC).

Specific heat capacity of the substance under the same conditions - 14.208 KJ / (CGKK) or 3,394 Cal / (GC ° C). This element is weakly soluble in water (about 0.0182 ml / g at 1 atm and 20 ° C), but well - in most metals (Ni, Pt, PA and others), especially in palladium (approximately 850 volumes per one PD ).

With the latest property, its diffusion ability is associated, while the diffusion through a carbon alloy (for example, steel) can be accompanied by the destruction of the alloy due to the interaction of hydrogen with carbon (this process is called decarbonization). In a liquid state, the substance is very easy (density - 0.0708 g / cm³ at t ° \u003d -253 ° C) and fluid (viscosity - 13.8 scholasis under the same conditions).

In many compounds, this element exhibits valence +1 (degree of oxidation), like sodium and other alkaline metals. It is usually considered as analogue of these metals. Accordingly, he heads the I group of the Mendeleev system. In the hydrides of metals, hydrogen ion shows a negative charge (the degree of oxidation at the same time -1), that is, Na + H- has a structure similar to Na + Cl- chloride. In accordance with this and some other facts (the proximity of the physical properties of the element "H" and halogen, the ability to replace it with halogens in organic compounds) Hydrogene belongs to the VII group of the Mendeleev system.

Under normal conditions, molecular hydrogen has low activity, directly connecting only with the most active non-metals (with fluorine and chlorine, with the latter - in the light). In turn, when heated, it interacts with many chemical elements.

Atomic hydrogen has increased chemical activity (if compared with molecular). With oxygen, it forms water by the formula:

N₂ + ½₂ \u003d N₂O,

highlighting 285.937 KJ / Mol heat or 68,3174 kcal / mol (25 ° C, 1 atm). In conventional temperature conditions, the reaction proceeds quite slowly, and at t °\u003e \u003d 550 ° C - uncontrollable. The explosion limits of the mixture of hydrogen + oxygen in volume are 4-94% H₂, and the mixtures of hydrogen + air - 4-74% H₂ (a mixture of two volumes of H₂ and one volume of O₂ is called rat gas.

This element is used to restore most metals, as it takes oxygen by oxides:

Fe₃O₄ + 4H₂ \u003d 3FE + 4N₂O,

Cuo + H₂ \u003d Cu + H₂o, etc.

With different halogens, hydrogen forms halogen hydrogen sodes, for example:

N₂ + CL₂ \u003d 2NSL.

However, when reactions with fluorine, hydrogen explodes (this occurs in the dark, at -252 ° C), with bromine and chlorine reacts only when heated or illumination, and with iodine - exclusively when heated. When interacting with nitrogen, ammonia is formed, but only on the catalyst, at elevated pressures and temperatures:

ZN₂ + N₂ \u003d 2NN₃.

When heated, hydrogen actively reacts with sulfur:

N₂ + S \u003d H₂S (hydrogen sulfide)

and it is much more difficult - with tellurium or selenium. With pure carbon, hydrogen reacts without a catalyst, but at high temperatures:

2N₂ + C (amorphous) \u003d CH₄ (methane).

This substance directly reacts with some of the metals (alkaline, alkaline earth and other), forming hydrides, for example:

H₂ + 2Li \u003d 2LIH.

Evaliable practical importance has the interactions of hydrogen and carbon oxide (II). In this case, depending on the pressure, temperature and catalyst, different organic compounds are formed: NSNO, CN₃on, etc. Unsaturated hydrocarbons in the reaction process are moving into saturated, for example:

With N ₂ n + H₂ \u003d C n ₂ n ₊₂.

Hydrogen and its compounds play an exceptional role in chemistry. It causes the acid properties of the T. N. Protonic acids are inclined to form a hydrogen bond with different elements that have a significant impact on the properties of many inorganic and organic compounds.

Obtaining hydrogen

The main types of raw materials for the industrial production of this element are gases of refining, natural combustible and coke gases. It is also obtained from water through electrolysis (in places with affordable electricity). One of the most important methods for the production of natural gas material is the catalytic interaction of hydrocarbons, mainly methane, with water vapor (T.N. Conversion). For example:

CH₄ + H₂O \u003d CO + ZN₂.

Incomplete oxidation of hydrocarbons with oxygen:

CH₄ + ½O₂ \u003d CO + 2N₂.

Synthesized carbon oxide (II) conversion:

CO + N₂O \u003d SO + H₂.

Hydrogen produced from natural gas is the cheapest.

For electrolysis of water, a constant current is used, which is passed through a solution of NaOH or con (acids are not used to avoid corrosion of instruments). In the laboratory, the material is obtained by electrolysis of water or as a result of the reaction between hydrochloric acid and zinc. However, more often use ready-made factory material in cylinders.

From the gas of oil refining and coke gas, this element is isolated by removing all other components of the gas mixture, since they are easier to liquefy with deep cooling.

Industrially, this material began to receive even at the end of the XVIII century. Then it was used to fill balloons. At the moment, hydrogen is widely used in industry, mainly in the chemical, for the production of ammonia.

Mass consumers of the substance are manufacturers of methyl and other alcohols, synthetic gasoline and many other products. They are obtained by synthesis of carbon oxide (II) and hydrogen. Hydrogene is used to hydrogenize heavy and solid liquid fuels, fats, etc., for the synthesis of HCl, hydrotreating of petroleum products, as well as in cutting / welding of metals. The most important elements for nuclear energy are its isotopes - tritium and deuterium.

Biological role of hydrogen

About 10% of the mass of living organisms (on average) falls on this element. It is part of the water and essential groups of natural compounds, including proteins, nucleic acids, lipids, carbohydrates. Why does it serve?

This material plays a decisive role: when maintaining the spatial structure of proteins (quaternary), in the implementation of the principle of nucleic acid complimentaryness (i.e., in the implementation and storage of genetic information), in general in "recognition" at the molecular level.

The hydrogen ion H + takes part in important dynamic reactions / processes in the body. Including: in biological oxidation, which provides living cells by energy, in biosynthesis reactions, in photosynthesis in plants, in bacterial photosynthesis and nitrogenation, in maintaining acid-alkaline balance and homeostasis, in the membrane transport processes. Along with carbon and oxygen, it forms a functional and structural basis of life phenomena.