Physical properties of hydrogen. Properties and application of hydrogen

Hydrogen H is a chemical element, one of the most common in our universe. The mass of hydrogen as an element in the composition of substances is 75% of the total content of atoms of a different type. He enters the most important and vital connection on the planet - water. A distinctive feature of hydrogen is also that it is the first element in the periodic system of chemical elements of DI Mendeleyev.

Discovery and research

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 combustible properties were already made in the seventeenth century by the scientist Lemery. The English chemist, physicist and natural scientist Henry Cavendish thoroughly studied the hydrogen, who proved by experience 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."

Characterization by position in PSHE

The element that opens DI Mendeleyev's periodic table is hydrogen. The physical and chemical properties of the atom show some kind of duality, since the hydrogen is simultaneously referred to the first group, the main subgroup, if it behaves like a metal and gives a single electron in the course of a chemical reaction, and to the seventh - in the case of a full valence shell filling, Negative particle, which characterizes it as similar to halogens.

Features of the electronic structure of the element

The properties of the hydrogen atom, the complex substances in which it enters, and the simplest H ₂ substance are primarily determined by the electronic configuration of the hydrogen. The 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 having one negative particle on the very first and only s-orbitals for the hydrogen.

With the detachment or recoil of the electron, and the atom of this element has such a property that it makes it related to metals, a cation is obtained. In fact, the hydrogen ion is a positive elementary particle. Therefore, an electron deprived of hydrogen is simply called a proton.

Physical properties

If to describe the physical properties of hydrogen briefly, this is a colorless, slightly soluble gas with a relative atomic mass equal to 2, 14.5 times lighter than air, with a liquefaction temperature of -252.8 degrees Celsius.

It is easy to see from experience that H ₂ is the lightest. To do this, it is enough to fill three spheres with various substances - hydrogen, carbon dioxide, ordinary air - and simultaneously release them from the hand. The fastest of all will be the one that is filled with CO ₂ , after it the inflated air mixture will drop, and the containing H2 will rise altogether to the ceiling.

The small mass and size of hydrogen particles justify its ability to penetrate various substances. On the example of the same ball, it's easy to be sure, after a couple of days, he himself will be blown off, since the gas will simply pass through the rubber. Also, hydrogen can accumulate in the structure of certain metals (palladium or platinum), and with increasing temperature evaporate from it.

The property of low solubility of hydrogen is used in laboratory practice for its isolation by the method of displacement of water. The physical properties of hydrogen (the table below shows the main parameters) determine the scope of its application and methods of production.

Isotopic composition

Like many other representatives of the periodic system of chemical elements, the 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 possessing 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, are significantly different from those of its counterparts. In particular, the features 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 of deuterium ² H - its isotope with two elementary particles: positive and uncharged. This isotope is two times heavier than the usual hydrogen, which explains the cardinal difference in the properties of the compounds that they make up. In nature, deuterium occurs 3200 times less frequently than hydrogen. The third representative is tritium 3H, in the nucleus it has two neutrons and one proton.

Methods of obtaining and extracting

The laboratory and industrial methods of obtaining hydrogen are very different. Thus, in small quantities, gas is produced mainly by reactions involving minerals, and large-scale production uses organic synthesis to a greater extent.

The following chemical interactions are used in the laboratory:

1. The reaction of alkali and alkaline earth metals with water to form alkali and the desired gas.
2. Electrolysis of the aqueous solution of the electrolyte, at the anode is released H ₂ ↑, and on the cathode - oxygen.
3. The decomposition of hydrides of alkali metals with water, products are alkali and, respectively, gas H ₂ ↑.
4. Interaction of dilute acids with metals to form salts and H ₂ ↑.
5. The action of alkalis on silicon, aluminum and zinc also contributes to the release of hydrogen in parallel with the formation of complex salts.

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

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

Chemical interactions: general provisions

The physical properties of hydrogen largely explain its behavior in the processes of reaction with a particular compound. The valence of the hydrogen is 1, since it is located in the first group in the Mendeleyev table, and the degree of oxidation is different. In all compounds, except hydrides, hydrogen in soy = (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 fairly stable energetically, which is why, under normal conditions, it is somewhat inert and in the reaction enters when the normal conditions change. Depending on the degree of oxidation 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 form 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 sulphide.
4. Oxygen + H2 = water.
5. Carbon + hydrogen = methane.
6. Nitrogen + H ₂ = ammonia.

Interaction with complex substances:

1. Synthesis gas production from carbon monoxide and hydrogen.
2. Recovery of metals from their oxides by H ₂ .
3. Hydrogen saturation of unsaturated aliphatic hydrocarbons.

Hydrogen bond

The physical properties of hydrogen are such that they allow it, while in conjunction with the electronegative element, to form a special type of bond with the same atom from neighboring molecules that have undivided 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 bonds, but due to the fact that there are many of them, they have a significant effect on the properties of matter. In fact, the hydrogen bond is an electrostatic interaction that binds water molecules to dimers and polymers, justifying its high boiling point.

Hydrogen in the composition of mineral compounds

The composition of all inorganic acids includes a proton-cation of an atom such as hydrogen. A substance whose acid residue has an oxidation degree greater than (-1) is called a polybasic compound. It contains several hydrogen atoms, which makes dissociation in aqueous solutions multistage. Each subsequent proton detaches from the rest of the acid more and more difficult. The quantitative content of hydrogen in the medium determines its acidity.

Hydrogen also contains hydroxyl groups of bases. In them, hydrogen is connected to an oxygen atom, as a result, the degree of oxidation of this residue of alkali is always equal to (-1). According to the content of hydroxyls in the medium, its basicity is determined.

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 in a darkish green color with a bright red inscription "Hydrogen". The gas is pumped into a balloon at a pressure of about 150 atmospheres. The physical properties of hydrogen, in particular the ease of the gaseous aggregate state, are used to fill it in a mixture with helium of balloons, balloons, etc.

Hydrogen, the physical and chemical properties of which people have learned to use many years ago, is currently used in many industries. Its bulk goes to the production of ammonia. Hydrogen is also involved in the production of metals (hafnium, germanium, gallium, silicon, molybdenum, tungsten, zirconium and others) from oxides, acting as a reducing agent, hydrocyanic acid, hydrochloric acid, methyl alcohol, and artificial liquid fuels. The food industry uses it to turn vegetable oils into solid fats.

The chemical properties and application of hydrogen in various processes of hydrogenation and hydrogenation of fats, coals, hydrocarbons, oils and fuel oil have been determined. With the help of it, precious stones, incandescent lamps are produced, forging and welding of metal products are carried out under the influence of an oxygen-hydrogen flame.