The most common element in the universe is hydrogen. In the material of stars, it has the form of nuclei - protons - and is a material for thermonuclear processes. Almost half of the mass of the sun also consists of H 2 molecules. Its content in the earth's crust reaches 0.15%, and atoms are present in the composition of oil, natural gas, and water. Together with oxygen, nitrogen and carbon, it is an organogenic element that is part of all living organisms on Earth. In our article we will study the physical and chemical properties of hydrogen, determine the main areas of its application in industry and its importance in nature.
The situation in the periodic system of chemical elements of Mendeleev
The first element that opens the periodic system is hydrogen. Its atomic mass is 1.0079. It has two stable (protium and deuterium) and one radioactive isotope (tritium). Physical properties are determined by the place of non-metal in the table of chemical elements. Under normal conditions, hydrogen (its formula is H 2 ) is a gas that is almost 15 times lighter than air. The atomic structure of an element is unique: it consists only of a nucleus and one electron. The substance’s molecule is diatomic, the particles in it are connected using a covalent non-polar bond. Its energy intensity is quite large - 431 kJ. This explains the low chemical activity of the compound under ordinary conditions. The electronic formula for hydrogen is: H: H.
The substance has a number of properties, analogues which are not among other non-metals. Let's consider some of them.
Solubility and thermal conductivity
Metals conduct heat best, but hydrogen approaches them in thermal conductivity. The explanation of the phenomenon lies in the very high speed of thermal motion of the light molecules of the substance, therefore in a hydrogen atmosphere a heated object cools 6 times faster than in air. The compound can dissolve well in metals, for example, nearly 900 volumes of hydrogen can be absorbed by one volume of palladium. Metals can enter into chemical reactions with H 2 in which the oxidizing properties of hydrogen are manifested. In this case, hydrides are formed:
2Na + H 2 = 2 NaH.
In this reaction, the atoms of the element take electrons from metal particles, turning into anions with a single negative charge. The simple substance H 2 in this case is an oxidizing agent, which is usually not characteristic of it.
Hydrogen as a reducing agent
Metal and hydrogen combine not only high thermal conductivity, but also the ability of their atoms in chemical processes to give their own electrons, that is, to oxidize. For example, basic oxides react with hydrogen. The redox reaction ends with the release of pure metal and the formation of water molecules:
CuO + H 2 = Cu + H 2 O.
The interaction of a substance with oxygen during heating also leads to the formation of water molecules. The process is exothermic and is accompanied by the release of a large amount of thermal energy. If the gas mixture of H 2 and O 2 reacts in a ratio of 2: 1, then it is called explosive gas, since when it ignites, it explodes:
2H 2 + O 2 = 2H 2 O.
Water is hydrogen oxide and plays a crucial role in the formation of the Earth’s hydrosphere, climate, and weather. It provides a cycle of elements in nature, supports all the vital processes of organisms - the inhabitants of our planet.
Interaction with non-metals
The most important chemical properties of hydrogen are its reactions with non-metallic elements. Under normal conditions, hydrogen molecules are sufficiently chemically inert, so the substance can only react with halogens, such as fluorine or chlorine, which are the most active among all non-metals. So, a mixture of fluorine and hydrogen explodes in the dark or in the cold, and with chlorine - when heated or in the light. The reaction products are hydrogen halides, aqueous solutions of which are known as fluoride and perchloric acids. The substance interacts with nitrogen at a temperature of 450-500 degrees, a pressure of 30-100 MPa and in the presence of a catalyst:
N₂ + 3H₂ ⇔ p, t, kat ⇔ 2NH₃.
The chemical properties of hydrogen considered are of great importance for industry. For example, you can get a valuable chemical product - ammonia. It is the main raw material for the production of nitric acid and nitrogen fertilizers: urea, ammonium nitrate.
Organic matter
The reaction of the compound between carbon and hydrogen produces the simplest hydrocarbon - methane:
C + 2H 2 = CH 4.
The substance is an essential component of natural and associated petroleum gas. They are used as a valuable fuel and raw material for the organic synthesis industry.
In the chemistry of carbon compounds, an element is part of a huge number of substances: alkanes, alkenes, carbohydrates, alcohols, etc. Many reactions of organic compounds with H 2 molecules are known. They are collectively called hydrogenation or hydrogenation. So, aldehydes can be reduced with hydrogen to alcohols, unsaturated hydrocarbons - to alkanes. For example, ethylene is converted to ethane:
C 2 H 4 + H 2 = C 2 H 6 .
Of great practical importance are the chemical properties of hydrogen, such as, for example, the hydrogenation of liquid oils: sunflower, corn, rapeseed. It leads to the production of solid fat - salomas, which are used in the production of glycerin, soap, stearin, hard varieties of margarine. To improve the appearance and taste of the food product, milk, animal fats, sugar, vitamins are added to it.
In our article, we studied the properties of hydrogen and found out its role in nature and human life.