In the periodic system, hydrogen is located in two groups of elements that are absolutely opposite in their properties. This feature makes it completely unique. Hydrogen is not just an element or substance, but also a component of many complex compounds, an organogenic and biogenic element. Therefore, we consider its properties and characteristics in more detail.
The release of combustible gas during the interaction of metals and acids was observed as early as the 16th century, that is, during the formation of chemistry as a science. The famous English scientist Henry Cavendish studied the substance starting in 1766 and gave it the name "combustible air". When burned, this gas produced water. Unfortunately, the scientist's adherence to the theory of phlogiston (hypothetical "hyperfine matter") prevented him from coming to the right conclusions.
The French chemist and naturalist A. Lavoisier, together with the engineer J. Meunier and with the help of special gasometers, in 1783 carried out the synthesis of water, and then its analysis by decomposing water vapor with red-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 suggested that the gas under study is a simple substance and, accordingly, is one of the primary chemical elements. He called it hydrogene (from the Greek words hydor - water + gennao - I give birth), that is, "giving birth to water."
The Russian name "hydrogen" was proposed in 1824 by the chemist M. Solovyov. The determination of the composition of water marked the end of the "phlogiston theory". At the turn of the 18th and 19th centuries, it was found that the hydrogen atom is very light (compared to the atoms of other elements) and its mass was taken as the main unit for comparing atomic masses, obtaining a value equal to 1.
Physical properties
Hydrogen is the lightest of all substances known to science (it is 14.4 times lighter than air), its density is 0.0899 g/l (1 atm, 0 °C). This material melts (solidifies) and boils (liquefies), respectively, at -259.1 ° C and -252.8 ° C (only helium has lower boiling and melting t °).
The critical temperature of hydrogen is extremely low (-240 °C). For this reason, its liquefaction is a rather complicated and costly process. The critical pressure of a substance is 12.8 kgf / cm², and the critical density is 0.0312 g / cm³. Among all gases, hydrogen has the highest thermal conductivity: at 1 atm and 0 ° C, it is 0.174 W / (mxK).
The specific heat capacity of a substance under the same conditions is 14.208 kJ / (kgxK) or 3.394 cal / (gh ° C). This element is slightly 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 (about 850 volumes per volume of Pd ).
The latter property is associated with its ability to diffuse, while diffusion through a carbon alloy (for example, steel) may be accompanied by the destruction of the alloy due to the interaction of hydrogen with carbon (this process is called decarbonization). In the liquid state, the substance is very light (density - 0.0708 g / cm³ at t ° \u003d -253 ° C) and fluid (viscosity - 13.8 centigrade under the same conditions).
In many compounds, this element exhibits a +1 valency (oxidation state), similar to sodium and other alkali metals. It is usually considered as an analogue of these metals. Accordingly, he heads the I group of the Mendeleev system. In metal hydrides, the hydrogen ion exhibits a negative charge (the oxidation state is -1), that is, Na + H- has a structure similar to Na + Cl- chloride. In accordance with this and some other facts (the closeness of the physical properties of the element "H" and halogens, the ability to replace it with halogens in organic compounds), Hydrogene is assigned to group VII of the Mendeleev system.
Under normal conditions, molecular hydrogen has low activity, directly combining only with the most active of 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 an increased chemical activity (compared to molecular hydrogen). With oxygen, it forms water according to the formula:
Н₂ + ½О₂ = Н₂О,
releasing 285.937 kJ/mol of heat or 68.3174 kcal/mol (25°C, 1 atm). Under normal temperature conditions, the reaction proceeds rather slowly, and at t ° >= 550 ° С, it is uncontrolled. The explosive limits of a mixture of hydrogen + oxygen by volume are 4–94% H₂, and mixtures of hydrogen + air are 4–74% H₂ (a mixture of two volumes of H₂ and one volume of O₂ is called explosive gas).
This element is used to reduce most metals, since it takes oxygen from oxides:
Fe₃O₄ + 4H₂ = 3Fe + 4Н₂О,
CuO + H₂ = Cu + H₂O etc.
With different halogens, hydrogen forms hydrogen halides, for example:
H₂ + Cl₂ = 2HCl.
However, when reacting with fluorine, hydrogen explodes (this also happens in the dark, at -252 ° C), reacts with bromine and chlorine only when heated or illuminated, and with iodine - only when heated. When interacting with nitrogen, ammonia is formed, but only on a catalyst, at elevated pressures and temperatures:
ZN₂ + N₂ = 2NH₃.
When heated, hydrogen actively reacts with sulfur:
H₂ + S = H₂S (hydrogen sulfide),
and much more difficult - with tellurium or selenium. Hydrogen reacts with pure carbon without a catalyst, but at high temperatures:
2H₂ + C (amorphous) = CH₄ (methane).
This substance directly reacts with some of the metals (alkali, alkaline earth and others), forming hydrides, for example:
Н₂ + 2Li = 2LiH.
Of no small practical importance are the interactions of hydrogen and carbon monoxide (II). In this case, depending on pressure, temperature and catalyst, various organic compounds are formed: HCHO, CH₃OH, etc. Unsaturated hydrocarbons turn into saturated ones during the reaction, for example:
С n Н₂ n + Н₂ = С n Н₂ n ₊₂.
Hydrogen and its compounds play an exceptional role in chemistry. It determines the acidic properties of the so-called. protic acids tend to form hydrogen bonds with different elements, which have a significant effect on the properties of many inorganic and organic compounds.
Getting hydrogen
The main types of raw materials for the industrial production of this element are refinery gases, natural combustible and coke oven gases. It is also obtained from water through electrolysis (in places with affordable electricity). One of the most important methods for producing material from natural gas is the catalytic interaction of hydrocarbons, mainly methane, with water vapor (the so-called conversion). For example:
CH₄ + H₂O = CO + ZH₂.
Incomplete oxidation of hydrocarbons with oxygen:
CH₄ + ½O₂ \u003d CO + 2H₂.
Synthesized carbon monoxide (II) undergoes conversion:
CO + H₂O = CO₂ + H₂.
Hydrogen produced from natural gas is the cheapest.
For electrolysis of water, direct current is used, which is passed through a solution of NaOH or KOH (acids are not used to avoid corrosion of the equipment). Under laboratory conditions, the material is obtained by electrolysis of water or as a result of the reaction between hydrochloric acid and zinc. However, more often used ready-made factory material in cylinders.
From refinery gases and coke oven gas, this element is isolated by removing all other components of the gas mixture, since they are more easily liquefied during deep cooling.
This material began to be obtained industrially at the end of the 18th century. Then it was used to fill balloons. At the moment, hydrogen is widely used in industry, mainly in the chemical industry, 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 from carbon monoxide (II) and hydrogen. Hydrogene is used for the hydrogenation of 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.
The biological role of hydrogen
About 10% of the mass of living organisms (on average) falls on this element. It is part of water and the most important groups of natural compounds, including proteins, nucleic acids, lipids, carbohydrates. What does it serve?
This material plays a decisive role: in maintaining the spatial structure of proteins (quaternary), in implementing the principle of complementarity of nucleic acids (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 with energy, in biosynthesis reactions, in photosynthesis in plants, in bacterial photosynthesis and nitrogen fixation, in maintaining acid-base balance and homeostasis, in membrane transport processes. Along with carbon and oxygen, it forms the functional and structural basis of the phenomena of life.
It has the shape of a ball, but imagined it as a disk and even a floating rectangle, fire, air, earth and water considered four basic elements of the universe. Who stopped calling water an element? Who deprived her of this high rank? ? A number of brave chemists, working independently, almost simultaneously made this discovery.
The discoverers of oxygen and hydrogen
Ever since the chemists pushed the alchemists and warlocks out of the retorts, the family of elements has grown at once. If a hundred years ago it numbered only 60 members, now, counting artificially obtained elements, there are a hundred of them. We will find their names, chemical sign, atomic weight and serial number in any chemical table. Only the names of the "ancestors" disappeared from it. The discoverers of oxygen and hydrogen are considered:- French chemist Antoine Laurent Lavoisier. He was the manager of a saltpeter and powder factory, and later, after the victory of the French bourgeois revolution, the commissioner of the national treasury, one of the most influential people in France.
- English chemist Henry Cavendish, originally from an old ducal family, who donated a large share of his fortune to science.
- Compatriot Cavendish, Joseph Priestley. He was a priest. As an ardent supporter of the French Revolution, Priestley was expelled from England and fled to America.
- Famous Swedish chemist Carl Wilhelm Scheele, pharmacist.
Oxygen - in water and air
Lavoisier, Priestley and Scheele made a number of experiments. First they discovered oxygen in water and air. Abbreviated in chemistry, it is denoted by the letter "O". When we saidThere is no life without waterthis has not yet been said to whom, in fact, the water owes its life-giving power. Now we can answer this question. The life-giving power of water is in oxygen. Oxygen is the most important element of the air envelope surrounding the Earth. Without oxygen, life goes out like a candle flame placed under a glass jar. Even the largest fire subsides if burning objects are thrown with sand, cutting off oxygen access to them.
Now do you understand why the fire in the stove burns so badly if the view is closed? The same combustion process occurs in our body during metabolism. The steam engine works by using the thermal energy of burning coal. In the same way, our body uses the energy of those nutrients that we consume. The air that we breathe is necessary for the "stove" - our body - to burn well, because our body must have a certain temperature. When we exhale, we release water in the form of vapor and combustion products. 
Lavoisier studied these processes and found that combustion is the rapid combination of various substances with oxygen in the air. This creates warmth. But Lavoisier was not satisfied with the fact that discovered oxygen. He wanted to know what substances oxygen combines with. Discovery of hydrogen
Almost simultaneously with Cavendish, who also decomposed water into its component parts, Lavoisier discovered hydrogen. This element is called "Hydrogenium", which means: Hydrogen is denoted by the letter "H". Let's examine again whether hydrogen is really in composition of water. Fill a beaker with ice and heat it over the flame of an alcohol lamp. (Alcohol, like any alcohol, is rich in hydrogen.) And what will we see? The outer side of the test tube will be covered with dew. Or hold a clean knife over a candle flame. The knife will also be covered with drops of water. Where does water come from? Water comes from fire. So fire is the source of water! This is not a new discovery, and yet it is amazing. Chemists would say this: when hydrogen is burned, in other words, Hydrogen combines with oxygen to form water vapor. That is why the test tube and the knife are covered with drops of water. That's how it happened discovery of the composition of water. So, hydrogen, which is 16 times lighter than oxygen and 14 times lighter than air, burns! At the same time, it generates a large amount of heat. In the past, balloons were filled with hydrogen. It was very dangerous. Now helium is used instead of hydrogen. You can also answer the second question:Why doesn't water burn?This question seems so simple that we didn't even ask it at first. Most will say:
The water is wet, so it doesn't burn.Wrong. Gasoline is "wet" too, but don't try to see if it's on fire! Water does not burn because it itself was formed as a result of combustion. This, one might say, is the "liquid ash" of hydrogen. That is why water puts out fire as well as sand.
03.10.2015
We all know that the most abundant element in our universe is hydrogen. It is the main constituent of stars. Of all atoms, its share is 88.6%. The processes taking place on Earth are simply not possible without the action of hydrogen. It, unlike many other elements, is in the form of various compounds. Its mass fraction of a simple substance in the air is negligible.
Name of the element in Latin Hydrogenium consists of two Greek words, translated meaning water and give birth- that is, giving birth to water. So called it Lavoisier, but in the XVII century. Academician V.M. Severgin decided to commemorate this element as a "water-forming substance". The name hydrogen in Russia was proposed in 1824 by the chemist Solovyov, by similarity as "oxygen". In the chemical literature of Russia until the 19th century, one can see such names of the element - combustible gas, combustible air or whirlpool, hydrogen gas, created creature.
For a long time, experiments on the study and discovery of many gases were ignored, since the experimenters simply did not notice these invisible substances. Only with time was the conviction consolidated that gas is the same material, without the study of which it is not possible to fully understand the chemical basis of the world. The discovery of hydrogen occurred in the very development of chemistry as a science. In the XI-XII centuries, gas was released during the interaction of the metal with acids. Paracelsus, Lomonosov, Boyle and other scientists and inventors observed its burning. But the main part of them in those years was committed to the theory of phlogiston.
Lomonosov, in 1745, when writing his dissertation, described the production of gas by the action of acids on metals. The phlogiston hypothesis was also put forward by the chemist Henry Cavendish, who studied the properties of hydrogen in more detail, giving it the name "combustible air". Only by the end of the 12th century, using modern laboratory instruments, Lavoisier, together with Meunier, carried out water synthesis. They made an analysis of water vapor, which was decomposed using hot iron. Thanks to this experience, it became clear that hydrogen is present in the composition of water; in addition, it can be obtained from it.
The turn of the XIII-XIX centuries was marked by one discovery - it was discovered that the hydrogen atom is quite light, along with other elements, it was customary to consider the weight of this element as a unit of comparison. Its atomic mass was assigned a value of 1. When Lavoisier presented the table of simple substances, he attributed hydrogen there to 5 simple bodies (hydrogen, oxygen, nitrogen, light, heat). It was generally accepted that these substances were from 3 natural kingdoms and were considered elements of bodies.
In addition to the discovery of the element itself, scientists later discovered its isotopes. It happened in more modern times, in 1931. A group of scientists was studying the residue, which was formed during the long evaporation of hydrogen in a liquid state. During the experiment, hydrogen was discovered, the atomic number of which was 2. It was given the name Deuterium (second). After only 4 years, during long-term electrolysis of water, an even heavier isotope was discovered, which was called Tritium (third).
Hydrogen in nature
Is there a lot of hydrogen in nature? Watching where. In space, hydrogen is the main element. It accounts for about half the mass of the Sun and most other stars. It is contained in gaseous nebulae, in interstellar gas, and is part of the stars. In the interior of stars, the nuclei of hydrogen atoms are converted into the nuclei of helium atoms. This process proceeds with the release of energy; for many stars, including the Sun, it serves as the main source of energy.
For example, the closest star to us in the Galaxy, which we know under the name "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 combined.
Hydrogen is widely distributed in nature, its content in the earth's crust (lithosphere and hydrosphere) is 1% by weight. Hydrogen is part of the most common substance on Earth - water (11.19% hydrogen by mass), in the compounds that make up coal, oil, natural gases, clay, as well as animal and plant organisms (that is, in the composition of proteins, nucleic acids , fats, carbohydrates, etc.). Hydrogen is extremely rare in the free state; it is found in small amounts in volcanic and other natural gases. Negligible amounts of free Hydrogen (0.0001% by number of atoms) are present in the atmosphere.
Task number 1. Fill in the table "Finding hydrogen in nature."
| In a free state | In bound state |
| Hydrosphere - | |
| Lithosphere - | |
| Biosphere - |
Discovery of hydrogen.
Hydrogen was discovered in the first half of the 16th century by the German physician and naturalist Paracelsus. In the works of chemists of the XVI-XVIII centuries. "combustible gas" or "flammable air" was mentioned, which, in combination with the usual one, gave explosive mixtures. It was obtained by acting on some metals (iron, zinc, tin) with dilute solutions of acids - sulfuric and hydrochloric.
The first scientist to describe the properties of this gas was the English scientist Henry Cavendish. He determined its density and studied combustion in air, however, adherence to the theory of phlogiston prevented the researcher from understanding the essence of the ongoing processes.
In 1779, Antoine Lavoisier obtained hydrogen by decomposing water by passing its vapors through a red-hot iron tube. Lavoisier also proved that when "combustible air" interacts with oxygen, water is formed, and the gases react in a volume ratio of 2: 1. This allowed the scientist to determine the composition of water - H 2 O. The name of the element is Hydrogenium- Lavoisier and his colleagues formed from the Greek words " hydro" - water and " gennio"I am giving birth. The Russian name "hydrogen" was proposed by the chemist M.F. Solovyov in 1824 - by analogy with Lomonosov's "oxygen".
Task number 2. Write the reaction for obtaining hydrogen from zinc and hydrochloric acid in molecular and ionic form, make an OVR.
Answer from Neurologist[guru]
Hydrogen gas was discovered by T. Paracelsus in the 16th century. when he immersed iron in sulfuric acid. But even then there was no such thing as gas.
One of the most important merits of the chemist of the XVII century.
Ya. B. van Helmont before science lies in the fact that it was he who enriched the human vocabulary with a new word - "gas", naming invisible substances that "which can neither be stored in vessels nor transformed into a visible body".
But soon the physicist R. Boyle came up with a way to collect and store gases in vessels. This is a very important step forward in the knowledge of gases, and Boyle's experience deserves a detailed description. He tipped a bottle filled with dilute sulfuric acid and iron nails upside down into a cup of sulfuric acid.
But here Boyle made a serious mistake. Instead of investigating the nature of the resulting gas, he identified this gas with air.
The amazing properties of gas, first collected by Boyle and so unacceptably confused with air, were discovered by N. Lemery, a contemporary of Boyle. "Combustible air" - from now on, this name will be fixed for a long time for the amazing gas released by iron from sulfuric acid. For a long time, but not forever, because this name is incorrect, or rather, inaccurate: combustible and some other gases. But if for a long time the researchers will confuse the gas "sulfuric acid and iron" with other combustible gases, then no one will confuse it, like Boyle, with ordinary air.
There was a man who undertook to uncover the secret of the origin of this gas. Nobility of origin provided him with a brilliant career as a statesman, and the wealth he accidentally acquired opened up all the possibilities for a carefree life. But Lord G. Cavendish neglected both for the sake of the satisfaction that comes from penetrating the secrets of nature.
Cavendish's first work, published in 1766, was devoted to "combustible air". First of all, it increases the number of ways to obtain "combustible air". It turns out that this gas is obtained with equal success if iron is replaced by zinc or tin, and sulfuric acid by hydrochloric acid. "Combustible air", however, does not support combustion, just like the breath of animals, which quickly die in its atmosphere.
Ten years after the publication of Cavendish's work, in 1766, a researcher named Macke, burning "flammable air", made an interesting observation.
To his surprise, he found that this flame did not leave any soot.
At the same time, he noticed something else: the saucer was covered with droplets of liquid, colorless as water. He and his assistant carefully examined the resulting liquid and found that it was indeed pure water.
A. Lavoisier doubted that the burning of "combustible air" produced water. A significant experiment was carried out on June 24, 1783 in the presence of several people. The result was not in doubt.
So, - Lavoisier concluded, - water is nothing but oxidized "combustible air" or, in other words, a direct product of the combustion of "combustible air" - in oxygen, devoid of light and heat released during combustion.
The sluggish Cavendish published his report in the Royal Society of London only in 1784, while Lavoisier presented his results before the Paris Academy of Sciences on June 25, 1783, a whole year ahead of his rival. In addition to Lavoisier, other persons participated in the discovery of the complex composition of water, including the famous English inventor James Watt, who is incorrectly credited abroad with the honor of inventing the steam engine.
Thus, the theoretical considerations were brilliantly confirmed, and along the way, a new method for obtaining "combustible air" was discovered.
