Sulfur is a substance currently studied by mankind almost completely. In ancient times, it was considered mystical, was surrounded by secrets, legends and myths that arose because of the superstitious fear of people before everything unknown. However, many physical properties of sulfur were known to people even before Mendeleev put the element in the periodic table and assigned it number 16. This substance was widely used in the era of Homer, in addition, some information (conditionally reliable) can be found in New and Old Testaments.
Chemical element
It was quite difficult to systematize over the centuries accumulated information about such a substance as sulfur. Many scientists were engaged in this, but D.I. Mendeleev managed to determine its belonging to the class of chemical elements . In the periodic system, it is indicated by number 16. Sulfur is located in the third period, the sixth group of the main subgroup, the atomic mass is 32, and the density (under normal conditions) is 2070 kg / m 3 .
Usage history
Ancient people actively used the physical properties of sulfur, which were known to them. The gods of the earth, or underground people endowed with special qualities, were considered the source of its occurrence. The characteristic smell of this substance and the ease of its ignition were useful to the ministers of the church during various religious rites and the expulsion of “evil spirits”. In the future, sulfur began to be used for military purposes, was part of the combustible mixtures. With a high degree of probability, it can be argued that it was used to create the "Greek fire", which brought holy fear to the enemy. In everyday life, sulfur and its compounds were used in cosmetology, agriculture, with its help bleached tissues and parasites were removed. In ancient China, the first pyrotechnic experiments were carried out using sulfur. The resulting mixtures were not yet gunpowder, but served as the basis for the creation of its formula, which, by the way, was modernized in modern conditions. However, at the initial stage, it was sulfur that was its basis. Chemistry, or rather, the alchemy of that time, calls this element "the father of all metals." A similar conclusion is based on the presence of sulfur in many ores and its increased combustibility. Lavoisier succeeds in dispelling this myth in 1789. The scientist attributed the element to non-metals and, as further studies showed, was right. In medicine, sulfur compounds have been used as antiseptic and antiparasitic agents.
In nature
In the rocks of the earth's crust, sulfur is quite common. In terms of accessibility and prevalence, it takes 16th place among all chemical elements. The structure of the sulfur atom allows this substance to be in its pure form (in certain natural conditions). But in most cases, it is part of various ores, and forms sulfides and sulfates in the compounds. Its most common bonds with metals are: iron pyrite (pyrite), cinnabar, lead luster (galena), zinc blende (sphalerite). In the oceans there are sulfates of magnesium, calcium, sodium. To date, more than 200 types of minerals have been identified. The second - in terms of the mass fraction of the content - the group is gypsum, kizerite, glauber's salt. Sulfur is a part of protein molecules, i.e. it is found in animal organisms. Organic compounds are very widely represented: oil, gases and natural coal. The main source of formation of sulfur and its derivatives are volcanic eruptions, but human activity (industrial, economic) accelerated and enriched this process. A significant amount of this substance is accumulated in groundwater, clay, gypsum, at the bottom of lakes and seas, in oil, natural gas and coal, in salt marshes and in the waters of the oceans. The sulfur cycle in the biosphere occurs with the help of microorganisms, and moisture contributes to this, which evaporates from the surface of a huge body of water, falls out in the form of precipitation and, with river flows, goes back to the seas and oceans.
Title
During the development of alchemy, there were several names that denoted the modern chemical element sulfur. What substance was meant by them is not entirely clear, perhaps it was a matter of compounds, ore or sulfur dioxide. In the periodic system of Mendeleev, sulfur is indicated by the symbol S (Sulfur). This Latin name does not have a clear origin, it was probably borrowed from the ancient Greek language, and it can be translated as “burning”. The term used in Russian has very ancient roots. The word "sulfur" denoted unpleasant smelling substances, combustible mixtures. There is also a version about the origin of the name from the color of the substance: "light yellow", "gray", that is, not defined. So called all the pitches. The second name of the substance, which is not used in modern times, is “bogey”. It also carries a definition of combustibility and foul smell. Philologists have come to the conclusion that the Sanskrit root “kill” is in this word, which is probably due to the properties of sulfur dioxide.
Physical properties of sulfur
Depending on the allotropic modification, the bonds within the element vary. It is customary to distinguish three formed types of lattice (a stable chain of atoms): rhombic, plastic, monoclinic. Color, physical properties of the substance sulfur depend on the modification. The most stable and common are the cyclic compounds S 8 . It is this kind of chain that is characteristic of crystalline sulfur, a brittle substance with a yellowish tint. Plastic and monoclinic modifications are unstable and go into a cyclic structure spontaneously some time after receipt. The sulfur formula in this case contains the symbol S 4 or S 6 . Under normal conditions (room temperature), a rhombic chain is a stable compound: during heating, the substance goes into a liquid state of aggregation, then thickens. Gradual cooling forms acicular crystals of monoclinic sulfur, which are dark yellow in color. When the molten substance interacts with cold water, a plastic allotropic modification is formed, which has a structure similar to rubber, consists of several polymer chains, and has a dirty yellow (dark) color. The most common description of sulfur is as a solid yellow substance that does not interact with water, remaining on its surface. Organic compounds can be used as a solvent: turpentine, carbon disulfide, etc. Sulfur as a simple substance under normal conditions has the following thermodynamic properties:
- The relative density is 2.070 g / cm 3 .
- Thermal conductivity - 300 K.
- Melting point - 112 about C.
- Molar specific heat is 22.6 J.
- Boiling point - 444 .
- The molar volume is 15.5 cm 3 / mol.
During heating, the number of sulfur atoms in the molecule decreases. At 300 ° C, it is a fairly actively moving liquid; to obtain vapors, the temperature is increased to 450 ° C. Monoatomic sulfur can be obtained by heating the substance to 1760 ° C (S 8 - S 6 - S 4 - S 2 - S). This substance is a poor conductor of electric current and heat, which is widely used in its application.
Chemical properties
Sulfur reacts with all metals, resulting in sulfides. In most cases, a chemical reaction requires a catalyst, which is heated. Under normal conditions (room temperature), the compound only occurs with mercury. This property is used to neutralize its vapors, which are formed as a result of the interaction of metal droplets with oxygen. The element does not interact with platinum, iridium, gold. The resulting sulfides are fire hazardous compounds that burn quite intensively when ignited. Sulfur refined outdoors reacts with oxygen. This compound is characterized by the formation of a colorless gas (sulfur dioxide) and combustion. A reversible reaction of interaction with hydrogen occurs upon heating (by analogy with carbon and silicon), the gases formed are called hydrogen sulfide, carbon disulfide. Like all other elements of group VI of the periodic table, sulfur interacts in a sealed tube with halogens (fluorine, bromine, chlorine, phosphorus). At room temperature, reaction is possible only with fluorine. Sulfur chloride is the substance most widely used in the chemical industry. It does not interact with water and acid solutions; compounds with alkali are reversible - they are formed upon exposure to a catalyst. Many existing acids and salts are formed as a result of the combination (temperature is a prerequisite) of sulfur with oxygen and hydrogen.
Electronic structure
The structure of the sulfur atom allows the element to manifest itself as an oxidizing agent and a reducing agent, and to have different valencies in a chemical reaction. This is due to the distribution of electrons over the levels. The atomic nucleus has a charge of +16 with an atomic mass of 32 (16 protons and neutrons), a radius of 127 pm. The sulfur scheme (electronic) is as follows: S + 16) 2) 8) 6; in a calm state - 1S 2 2S 2 2P 6 3S 2 3P 4 . At the third level, the sulfur atom has five unoccupied orbitals, so the valency in its compounds varies in the following ranges: -2, + 2, + 4, + 6, which depend on the degree of its excitation.
Place of Birth
The amount of sulfur produced is increasing annually. This is due to a fairly wide range of its application, which is constantly growing due to technological breakthroughs and a more thorough study of already known chemical elements. In nature, sulfur is contained in a native form and is part of a large number of ores. Depending on this, various methods of its extraction are used. Stratiform deposits are common in the USA, Iraq, the middle Volga region and the Carpathian region. They are the most cost-effective in percentage terms, they produce from 50 to 60% of sulfur there. Carbonate and sulfate rocks lie in huge strata, reaching tens of meters in depth and several hundred in length. Salt-domed deposits are characteristic of regions of intensive oil product extraction. The largest deposits include the Gulf of Mexico zone, which is simultaneously being developed by the USA, Chile and Mexico. The most modern, recently formed deposits are volcanic deposits. Their origin is associated with tectonic faults of the earth's crust and the action of volcanoes. Accordingly, these deposits are located in the Pacific Ocean. Actively master these zones Japan and Russia. On the territory of Eurasia, deposits of native sulfur are more common, which has a fairly ancient origin and is mainly located in the surface layers. The Ural Mountains, the island of Sicily, the Volga region, Lviv region are developed deposits that are being developed to this day. World sulfur production is more than 50 million tons per year, with 30% - nuggets, 33% - gas and oil products, 14% - processing of industrial emissions, 16% - from sulfides, 6% - from sulfates.
Mining methods
Depending on the depth of the sulfur-containing ore, various methods for its extraction and further processing are used. The physical properties of sulfur to the forefront, regardless of the mining method, bring the safety of the process. As a rule, deposits of this substance are accompanied by a large accumulation of toxic gases, and cases of spontaneous combustion are not excluded. Surface ore layers are removed by layers with the help of excavators - this method is the least dangerous (subject to all technological requirements). Refined sulfur is obtained as a result of its further processing at the appropriate enterprises, where it is delivered from quarries. The methods of purification and enrichment are diverse: thermal, centrifugal, filtration, steam-water, extraction.
It is much more difficult to produce sulfur, which is contained in the underground layers. The mine method - due to the release of associated gas - is practically inaccessible, therefore, the German Frash method has been used quite successfully since 1895. It is most productive in the development of rich deposits and provides significant savings in transportation costs and the cost of further processing of ore, since it assumes the yield of pure substance. The installation principle is simple: ore layers containing sulfur are treated with hot water, which is supplied through a pipe. Inside it are two more cylindrical separate vessels, which are designed to supply gas and exit the finished product. Due to the low melting point, sulfur with a small amount of impurities comes to the surface under pressure.
Application
The main consumer of sulfur is the chemical industry, which cannot exist without acids based on this element. Textile, oil refining, food, cellulose, mining segments of production cannot do without this substance. The sulfur formula makes it possible to use its compounds for the manufacture of explosives, matches, rubber, cosmetics, medicines, etc. In agriculture, the substance we are considering is a part of fertilizers for the soil (increases the percentage of phosphorus absorbed) and poisons that process seeds from various pests.
Refined sulfur is used to produce dyes and luminous compounds. By the degree of extraction, processing and use of this element, one can judge the industrial potential of the entire state. Most of the latest developments in many high-tech sectors of the economy are based on the use of sulfur and its compounds. It is difficult to assess the full potential of the use of this chemical element, which has been used by mankind since ancient times and continues to actively participate in the technological evolutionary process.