Mercury (Hg, from lat. Hydrargyrum) - an element of the sixth period of the periodic system of chemical elements of D.I. Mendeleev with atomic number 80, belonging to the zinc subgroup (a side subgroup of group II). Simple substance mercury- a transition metal, at room temperature it is a heavy silvery-white liquid, the vapors of which are extremely toxic. Mercury is one of two chemical elements (and the only metal), the simple substances of which, under normal conditions, are in a liquid state of aggregation (the second such element is bromine).
1. History
origin of name
2 Being in nature
2.1 Deposits
3 In the environment
4 Isotopes
5 Receipt
6 Physical properties
7 Chemical properties
7.1 Characteristic oxidation states
7.2 Properties of metallic mercury
8 Use of mercury and its compounds
8.1 Medicine
8.2 Technique
8.3 Metallurgy
8.4 Chemical industry
8.5 Agriculture
9 Mercury toxicology
9.1 Hygienic regulation of mercury concentrations
9.2 Demercurization
Story
Astronomical symbol of the planet Mercury
Mercury has been known since ancient times. It was often found in its native form (liquid drops on rocks), but more often it was obtained by firing natural cinnabar. The ancient Greeks and Romans used mercury to purify gold (amalgamation) and knew about the toxicity of mercury itself and its compounds, in particular sublimate. For many centuries, alchemists considered mercury to be the main component of all metals and believed that if liquid mercury was restored to hardness with the help of sulfur or arsenic, gold would be obtained. The isolation of mercury in its pure form was described by the Swedish chemist Georg Brandt in 1735. To represent the element, both alchemists and today use the symbol of the planet Mercury. But the belonging of mercury to metals was proven only by the works of Lomonosov and Brown, who in December 1759 were able to freeze mercury and establish its metallic properties: malleability, electrical conductivity, etc.
origin of name
The Russian name for mercury comes from praslav. *rtǫ tь, associated with lit. rìsti"roll". The symbol Hg is borrowed from the Latin alchemical name for this element hydrargyrum(ancient Greek: ὕδωρ “water” and ἄργυρος “silver”).
Being in nature
Mercury is a relatively rare element in the earth's crust with an average concentration of 83 mg/t. However, due to the fact that mercury weakly binds chemically to the most common elements in the earth's crust, mercury ores can be very concentrated compared to ordinary rocks. The most mercury-rich ores contain up to 2.5% mercury. The main form of mercury in nature is dispersed, and only 0.02% of it is contained in deposits. The mercury content in different types of igneous rocks is close to each other (about 100 mg/t). Among sedimentary rocks, the maximum concentrations of mercury are found in clay shales (up to 200 mg/t). In the waters of the World Ocean, the mercury content is 0.1 μg/l. The most important geochemical feature of mercury is that among other chalcophile elements it has the highest ionization potential. This determines such properties of mercury as the ability to be reduced to an atomic form (native mercury), significant chemical resistance to oxygen and acids.
Mercury is present in most sulfide minerals. Its especially high contents (up to thousandths and hundredths of a percent) are found in fahlores, stibnites, sphalerites and realgars. The proximity of the ionic radii of divalent mercury and calcium, monovalent mercury and barium determines their isomorphism in fluorites and barites. In cinnabar and metacinnabarite, sulfur is sometimes replaced by selenium or tellurium; The selenium content is often hundredths and tenths of a percent. Extremely rare mercury selenides are known - timanite (HgSe) and onofrite (a mixture of timanite and sphalerite).
Mercury is one of the most sensitive indicators of hidden mineralization not only of mercury, but also of various sulfide deposits, therefore mercury halos are usually detected above all hidden sulfide deposits and along pre-ore faults. This feature, as well as the low mercury content in rocks, is explained by the high elasticity of mercury vapor, which increases with temperature and determines the high migration of this element in the gas phase.
Under surface conditions, cinnabar and metallic mercury are insoluble in water, but in their presence (Fe 2 (SO 4) 3, ozone, hydrogen peroxide), the solubility of these minerals reaches tens of mg/l. Mercury dissolves especially well in sulfides of caustic alkalis with the formation, for example, of the HgS nNa 2 S complex. Mercury is easily sorbed by clays, iron and manganese hydroxides, shales and coals.
About 20 mercury minerals are known in nature, but the main industrial value is cinnabar HgS (86.2% Hg). In rare cases, the subject of extraction is native mercury, metacinnabarite HgS and fahl ore - schwatzite (up to 17% Hg). At the only Guitzuco deposit (Mexico), the main ore mineral is livingstonite HgSb 4 S 7. In the oxidation zone of mercury deposits, secondary mercury minerals are formed. These include, first of all, native mercury, less commonly metacinnabarite, which differ from the same primary minerals in greater purity of composition. Calomel Hg 2 Cl 2 is relatively common. Other supergene halide compounds are also common at the Terlingua deposit (Texas): terlinguaite Hg 2 ClO, eglestonite Hg 4 Cl.
There is hardly any need to prove that mercury is a unique metal. This is obvious, if only because mercury is the only metal that is in a liquid state under conditions that we call normal. Why mercury is liquid is a special question. But it was precisely this property, or rather the combination of the properties of metal and liquid (the heaviest liquid!) that determined the special position of element No. 80 in our lives. You can talk a lot about mercury: dozens of books are devoted to the liquid metal. This same story is mainly about the variety of uses of mercury and its compounds.
The involvement of mercury in the glorious clan of metals has long been in doubt. Even Lomonosov hesitated whether mercury could be considered a metal, despite the fact that in the liquid state it has almost the full range of metallic properties: thermal and electrical conductivity, metallic luster, and so on. When mercury is cooled to –39°C, it becomes quite obvious that it is one of the “light bodies that can be forged.”
Liquid metal
Mercury has rendered enormous services to science. Who knows how much the progress of technology and natural sciences would have been delayed without measuring instruments - thermometers, pressure gauges, barometers and others, the action of which is based on the extraordinary properties of mercury. What are these properties?
Firstly, mercury is a liquid.
Secondly, the heavy liquid is 13.6 times heavier than water.
Thirdly, mercury has a fairly large coefficient of thermal expansion - only one and a half times less than that of water, and an order of magnitude, or even two, more than that of ordinary metals.
There are also “fourths”, “fifths”, “twenties”, but it is hardly necessary to list everything.
Another interesting detail: “millimeter of mercury” is not the only physical unit associated with element No. 80. One definition of an ohm, a unit of electrical resistance, is the resistance of a column of mercury 106.3 cm long and 1 mm 2 in cross section.
All this has to do not only with pure science. Thermometers, pressure gauges and other instruments “stuffed” with mercury have long become a part of not only laboratories, but also factories. And mercury lamps, mercury rectifiers! The same unique combination of properties has given mercury access to a variety of branches of technology, including radio electronics and automation.
Mercury rectifiers, for example, have long been the most important, powerful, and most widely used type of electrical current rectifier in industry. They are still used in many electrochemical industries and in vehicles with electric traction, although in recent years they have been gradually replaced by more economical and harmless semiconductor rectifiers.
Modern military equipment also uses the remarkable properties of liquid metal.
For example, one of the main parts of the fuse for an anti-aircraft projectile is a porous ring made of iron or nickel. The pores are filled with mercury. A shot is fired - the projectile has moved, it acquires increasing speed, rotates faster and faster around its axis, and heavy mercury protrudes from the pores. It closes the electrical circuit - an explosion.
You can often encounter mercury where you least expect it. Mercury is sometimes alloyed with other metals. Small additions of element No. 80 increase the hardness of the lead alloy with alkaline earth metals. Even when soldering, mercury is sometimes needed: solder made from 93% lead, 3% tin and 4% mercury is the best material for soldering galvanized pipes.
Amalgams
Another remarkable property of mercury: the ability to dissolve other metals, forming solid or liquid solutions - amalgams. Some of them, such as silver and cadmium amalgams, are chemically inert and hard at human body temperature, but soften easily when heated. They are used to make dental fillings.
Thallium amalgam, which hardens only at –60°C, is used in special designs of low-temperature thermometers.
Ancient mirrors were not coated with a thin layer of silver, as is done now, but with an amalgam, which included 70% tin and 30% mercury. In the past, amalgamation was the most important technological process in extracting gold from ores. In the 20th century, it could not withstand the competition and gave way to a more advanced process - cyanidation. However, the old process is still used today, mainly in the extraction of gold finely embedded in ore.
Some metals, in particular iron, cobalt, nickel, are practically not amenable to amalgamation. This makes it possible to transport liquid metal in containers made of plain steel. (Especially pure mercury is transported in containers made of glass, ceramics or plastic.) In addition to iron and its analogues, tantalum, silicon, rhenium, tungsten, vanadium, beryllium, titanium, manganese and molybdenum are not amalgamated, that is, almost all metals used for alloying become. This means that alloy steel is not afraid of mercury.
But sodium, for example, amalgamates very easily. Sodium amalgam is easily decomposed by water. These two circumstances have played and continue to play a very important role in the chlorine industry.
When producing chlorine and caustic soda by electrolysis of table salt, cathodes made of metallic mercury are used. To obtain a ton of caustic soda you need from 125 to 400 g of element No. 80. Today, the chlorine industry is one of the largest consumers of metallic mercury.
Mercury vapor
Mercury boils at 357°C, i.e. when most metals are still far from their melting point. This was known in ancient times, and methods for extracting metallic mercury from ores have long been based on this property. The very first method was firing cinnabar with condensation of mercury vapor on cold objects and, in particular, on freshly cut green trees. Later, retorts made of ceramics and cast iron began to be used. Since 1842, mercury has been extracted from ores in reverberatory furnaces, and since 1857 - in cascade furnaces. In the 20th century These were joined by mechanical multi-hearth furnaces, as well as rotary tube furnaces.
Cinnabar contains 86.2% mercury, but in ores considered rich, its share averages 8%. Low-grade ores contain no more than 0.12% mercury. Such ores must be enriched in one way or another, “weeding out” useless components.
And now mercury is extracted from ores and concentrates mainly by pyrometallurgical methods. Firing takes place in shaft, reverberatory or tube furnaces at 700...750°C. Such a high temperature is needed so that the cinnabar oxidizes rather than sublimes, and so that the oxidation process HgS + O 2 → Hg + SO 2 goes to completion. As a result of firing, vaporous mercury is obtained, which is converted into liquid metal in special devices - capacitors.
Although the gases formed during roasting go through several stages of purification, it is not so much metallic mercury that condenses, but the so-called mortar - a finely dispersed mixture consisting of tiny droplets of mercury and fine dust of a complex chemical composition. The stupa contains compounds of both mercury itself and other elements. It is subjected to beating, trying to destroy the dust films that interfere with the merging of microscopically small droplets of liquid metal. Repeated distillation also serves the same purpose. But it is still not possible to extract all the mercury from the mortar, and this is one of the problems of mercury metallurgy that remains unresolved today. But this is one of the oldest branches of metallurgy.
The ability of mercury to evaporate at a relatively low temperature was used to apply gold coatings to base metals. It is in this way that the dome of St. Isaac's Cathedral in Leningrad is gilded. Now this method has fallen out of use due to the toxicity of mercury vapor. Electrochemical methods of gilding are more advanced and safer.
But to see only poison in mercury vapor is wrong. They can and do bring a lot of benefits.
In 1936, it was reported that one of the foreign oil companies had acquired a mercury mine. It turned out that this company needed mercury to organize a steam-mercury plant intended for oil purification. Nowadays, mercury vapor is increasingly used in the oil refining industry: they help to very accurately regulate the temperature of processes, which is extremely important for oil refining.
Even earlier, at the beginning of the 20th century, the attention of heating engineers was attracted by a message about the work of Dr. Emmett from the USA. Emmett was the first to try to use mercury rather than water in steam boilers. Its pilot plant has a power of 2000 hp. worked and consumed 45% less fuel than a conventional steam boiler with a generator. Of course, there were some discussions: mercury is not water, you can’t scoop it up from a river! There were more than enough objections to the use of mercury in steam boilers. Research, however, continued.
The work of Soviet research institutes on the problem of using a mercury boiler and turbine was very successful. The efficiency of mercury-steam turbines and the possibility of creating the so-called mercury-water binary cycle, in which the heat of condensing mercury vapor is used in a special evaporator condenser to produce water vapor, have been proven. And before this, the mercury vapor manages to rotate the generator shaft. The resulting water steam drives a second electric turbine generator... In such a system, operating only on water steam, it is possible to achieve, at best, an efficiency of 30%. The theoretical efficiency of the mercury-steam cycle (45%) is much higher than that of a gas turbine (18...20%) and diesel (35...39%). In the 50s, there were already several such power plants in the world with a capacity of up to 20 thousand kilowatts. Unfortunately, the matter did not go further, mainly due to a lack of mercury.
Vacuum installations are very important for science and industry in our time. And here mercury is found not only as a filler in vacuum gauge tubes. Back in 1916, Irving Langmuir created a vacuum pump in which mercury evaporated and condensed. At the same time, a residual pressure was created in the system connected to the pump, hundreds of millions of times less than atmospheric pressure.
Modern mercury diffusion pumps provide even greater vacuum: hundred millionths of a millimeter of mercury.
The study of ultraviolet rays progressed slowly until an artificial source of these rays was created. It turned out to be mercury vapor in a vacuum. When an electric current is passed through mercury vapor, it emits a visible blue glow and many ultraviolet rays. The higher the temperature of mercury vapor, the more intense the radiation of ultraviolet rays in a mercury-quartz lamp.
The visible glow of mercury vapor is used in the design of powerful lighting lamps. Fluorescent lamps are discharge tubes containing inert gases and mercury vapor. And what “cold light” is is probably unnecessary to explain. Of every ruble that we pay “for light,” only four kopecks are actually emitted by light. The remaining 96 are for unnecessary heat emitted by conventional light bulbs. Fluorescent lamps are much more economical.
Mercury compounds
The first of them, undoubtedly, should be called cinnabar HgS. Thanks to her, man became acquainted with mercury many centuries ago. This was facilitated by its bright red color and the ease of obtaining mercury from cinnabar. Cinnabar crystals are sometimes coated with a thin lead-gray film. This is metacinnabarite, more about it below. However, it is enough to run a knife across the film and a bright red line will appear.
In nature, mercury sulfide occurs in three modifications, differing in crystal structure. In addition to the well-known cinnabar with a density of 8.18, there is also black metacinnabarite with a density of 7.7 and the so-called beta cinnabar (its density is 7.2). Russian craftsmen, when preparing red paint from cinnabar ore in the old days, paid special attention to removing “sparks” and “stars” from the ore. They did not know that these were allotropic changes of the same mercury sulphide; when heated without access to air to 386°C, these modifications turn into “real” cinnabar.
Some mercury compounds change color with temperature changes. These are red mercury oxide HgO and copper-mercury iodide HgI 2 · 2CuI.
All mercury salts are poisonous and require great care when handling them. People of different professions have to deal with mercury compounds. Mercury salt of chromic acid, for example, is a wonderful green paint for ceramics. Sublimate HgCl 2 is a strong poison, but it is extremely necessary in electroplating, in the production of tin and zinc alloys of fine structure, in the processes of engraving and lithography, even in photography. Some mercury salts, including sublimate, are used in dry electric batteries.
Industrial catalysis also cannot do without mercury compounds. One of the methods for producing acetic acid and ethyl alcohol is based on a reaction discovered by the Russian scientist M.G. Kucherov. The raw material is acetylene. In the presence of catalysts - divalent mercury salts - it reacts with water vapor and turns into acetaldehyde. Oxidizing this substance produces acetic acid, and reducing it produces alcohol. The same salts help obtain phthalic acid from naphthalene, an important product of basic organic synthesis.
Mercury consumption increases sharply during war years. Liquid metal is needed to produce “mercury fulminate” Hg(ONC) 2, the first initiating explosive known to technology. Although other similar explosives are now in service (lead azide, for example), “mercury fulminate” continues to be one of the most important materials for filling detonator capsules.
The toxicity of mercury compounds limits their use, but sometimes this property can be useful. The bottoms of ships are covered with mercury paints to prevent them from becoming overgrown with shells. Otherwise, the ship reduces speed and fuel is overused. The most famous of this type of paint is made on the basis of the acidic mercury salt of arsenic acid HgHAsO 4. True, recently synthetic dyes that do not contain mercury have been used for this purpose.
Although all mercury salts are poisonous, many of them are used medicinally, and this is perhaps one of their most ancient uses. Sublimate is a poison, but also one of the first antiseptics. Mercury cyanide was used in the production of antiseptic soap. Yellow mercuric oxide* is still used in the treatment of eye and skin diseases. Calomel Hg 2 Cl 2, in the molecule of which there is one “extra” mercury atom compared to the mercuric molecule, is a well-known laxative. Medicine also uses phosphate salts of mercury, its sulfate, iodide and others. Nowadays, most inorganic mercury compounds are gradually being replaced from medicine by organic mercury compounds, which are incapable of easy ionization and therefore are not so toxic and less irritating to tissues. Organic antiseptics based on mercury compounds are even suitable for treating mucous membranes. They provide no less therapeutic effect than inorganic compounds.
* When ground very finely, the red mercuric oxide HgO turns yellow. This modification is also obtained when mercury oxide precipitates.
Medicine uses not only compounds, but also mercury itself and its vapors. When starting an examination, the doctor first uses a “thermometer” - a mercury thermometer. Mercury manometers work in blood pressure measuring machines. In every hospital, in the physiotherapy rooms of clinics, ultraviolet rays received from mercury-quartz lamps deeply warm tissues, help treat catarrhs, inflammations, even tuberculosis - after all, ultraviolet radiation is destructive for many microorganisms.
Mercury is an ancient, amazing and, one might say, “ageless” metal. Known since time immemorial, it is finding new applications in modern technology, medicine, and everyday life.
Among the ancient peoples
History has not preserved the name of the ancient metallurgist who was the first to obtain mercury - this was too long ago, many centuries BC. It is only known that in Ancient Egypt, metallic mercury and its main mineral, cinnabar, were used back in the 3rd millennium BC. Hindus discovered mercury in the 2nd...1st centuries. BC. Among the ancient Chinese, cinnabar enjoyed special fame, not only as a paint, but also as a medicine. Mercury and cinnabar are mentioned in Pliny the Elder's Natural History, which means the Romans also knew about them. Pliny also testifies that the Romans knew how to turn cinnabar into mercury.
All metals are made of mercury... Alchemists of antiquity and the Middle Ages were convinced of this. They explained the difference in the properties of metals by the presence in the metal of one of Aristotle’s four elements. (Recall that these elements were: fire, air, water and earth.) It is characteristic that many prominent scientists of the distant past held similar views. Thus, the great Tajik physician and chemist Avicenna (980...1037 AD) also believed that all metals originated from mercury and sulfur.
Lavoisier tells
“Into this retort I introduced 4 ounces of very pure mercury, then by suction by means of a siphon, which I inserted under the bell, I raised the mercury to a certain level and carefully measured this level with a strip of glued paper, while accurately observing the readings of the barometer and thermometer.
Having thus completed all the preparations, I lit a fire in the stove and maintained it almost without interruption for 12 days, while the mercury was heated to the temperature necessary for it to boil. During the entire first day, nothing remarkable happened: the mercury, although boiling, was in a state of continuous evaporation and covered the inner walls of the retort with droplets, at first very small, but gradually increasing upon reaching a certain volume, falling from its own gravity to the bottom of the retort and connecting with the rest mercury.
On the second day, I began to notice small red particles floating on the surface of the mercury, which increased in number and volume for four or five days, after which they stopped increasing and remained absolutely unchanged. After 12 days, seeing that the calcification of the mercury was no longer progressing, I put out the fire and allowed the device to cool. The volume of air contained both in the retort and in its neck and in the free part of the bell... was approximately 50 cubic meters before the experiment. inches At the end of the operation, the same volume at the same pressure and the same temperature turned out to be equal to only 42...43 inches; consequently, there was a decrease of approximately one-sixth. On the other hand, having carefully collected the red particles that had formed on the surface and separated them, as far as possible, from the liquid mercury in which they floated, I found their weight to be 45 grains...
The air remaining after this operation and reduced due to the calcination of mercury in it to five-sixths of its volume, was no longer suitable for breathing or combustion; animals introduced into it died in a short time, while burning objects went out in an instant, as if they had been immersed in water. On the other hand, I took 45 grains of the red substance formed during the experiment and placed it in a small glass retort, to which was attached an apparatus adapted to receive the liquid and airy products that could be released; After lighting the fire in the stove, I noticed that as the red substance warmed up, its color became more and more intense. When the retort then began to heat up, the red substance began to decrease little by little in volume and in a few minutes it completely disappeared; at the same time, 41 1/2 grains of liquid mercury collected in a small receiver, and 7...8 cubic meters passed under the bell. inches of elastic liquid*, much more capable of supporting combustion and respiration of animals than atmospheric air...
* This is what gases were called in Lavoisier’s time.
I first gave it the name of extremely easily inhaled or very breathable air: later this name was replaced by the name “vital” or “life-giving air.”
Antoine Laurent Lavoisier.
"Analysis of Atmospheric Air". "Notes of the French Academy of Sciences", 1775.
Mercury and the discoveries of Joseph Priestley
But Lavoisier was not the first scientist to obtain oxygen from red mercuric oxide. Karl Scheele, back in 1771, decomposed this substance into mercury and “fire air,” and the outstanding English chemist Joseph Priestley was the first in the world to study oxygen. On August 1, 1774, having decomposed the oxide by heating, Priestley introduced a burning candle into the resulting “air” and saw that the flame had acquired an unusual brightness.
In this air the candle burned faster. Having flared up brightly, both hot pieces of coal and iron wires burned in it... This experiment was followed by others, and eventually Priestley identified the most important qualities of “dephlogistonized air.”
Joseph Priestley made many more important discoveries, and almost all of his work used mercury. It was she who helped Priestley discover hydrogen chloride gas. The interaction of table salt with sulfuric acid was observed by many chemists even before Priestley. But they all tried to collect the resulting gas above the water, and the result was hydrochloric acid. Priestley replaced water with mercury... In the same way, he obtained pure ammonia gas from ammonia. Then it turned out that the two gases he discovered - NH 3 and HCl - are capable of reacting with each other and turning into small white crystals. This is how ammonium chloride was obtained for the first time in laboratory conditions. Sulfur dioxide was also discovered by Priestley and was also collected above mercury.
The mercury cathode came to the rescue
In 1807, by decomposing alkalis with electric current, the outstanding English scientist Davy first obtained elemental sodium and potassium. His experiments were repeated by the leading Swedish chemist Berzelius, but the current source—the voltaic column—that he had at his disposal was too weak, and Davy Berzelius initially failed to reproduce the results. Then he decided to use mercury as a cathode and... obtained alkali metals with less energy consumption. Meanwhile, Davy tried to isolate alkaline earth metals using electricity. In doing so, he burned out his huge battery and wrote to Berzelius about this failure. He advised him to use a mercury cathode, and in 1808 Davy obtained calcium amalgam, from which it was no longer difficult to isolate the metal. In the same year (and in the same way), Davy isolated barium, strontium and magnesium in elemental form.
First superconductor
Almost a century and a half after the experiments of Priestley and Lavoisier, mercury was involved in another outstanding discovery, this time in the field of physics. In 1911, the Dutch scientist Geike Kamerlingh Onnes studied the electrical conductivity of mercury at low temperatures. With each experiment, he decreased the temperature, and when it reached 4.12°K, the resistance of the mercury, which had previously been consistently decreasing, suddenly disappeared completely: the electric current passed through the mercury ring without dying out. This is how the phenomenon of superconductivity was discovered, and mercury became the first superconductor. Dozens of alloys and pure metals are now known that acquire this property at temperatures close to absolute zero.
How to clean mercury
In chemical laboratories there is often a need to purify liquid metal. The method described in this note is perhaps the simplest of the reliable and the most reliable of the simple. A glass tube with a diameter of 1...2 cm is mounted on a tripod; the lower end of the tube is pulled back and bent. Dilute nitric acid with approximately 5% mercuric nitrate Hg 2 (NO 3) 2 is poured into the tube. A funnel with a paper filter is inserted into the tube from above, in the bottom of which a small hole is made with a needle. The funnel is filled with contaminated mercury. On the filter it is cleared of mechanical impurities, and in the tube - from most of the metals dissolved in it. How does this happen? Mercury is a noble metal, and impurities, such as copper, displace it from Hg 2 (NO 3) 2; Some impurities are simply dissolved by acid. Purified mercury is collected at the bottom of the tube and, under the influence of its own gravity, is pressed into the receiving vessel. By repeating this operation several times, it is possible to completely cleanse mercury of the impurity of all metals located in the voltage series to the left of mercury.
Purifying mercury from noble metals such as gold and silver is much more difficult. To separate them, vacuum distillation is used.
It is not only the liquid state that mercury is related to water. The heat capacity of mercury, like water, consistently decreases with increasing temperature (from the melting point to +80°C) and only after a certain temperature “threshold” (after 80°C) begins to slowly increase. If you cool mercury very slowly, it, like water, can become supercooled. In its supercooled state, liquid mercury exists at temperatures below –50°C, but usually freezes at –38.9°C. By the way, mercury was first frozen in 1759 by St. Petersburg academician I.A. Brown.
There is no monovalent mercury!
This statement will seem incorrect to many. After all, even at school they teach that, like copper, mercury can exhibit valences of 2+ and 1+. Such compounds as black oxide Hg 2 O or calomel Hg 2 Cl 2 are widely known. But mercury here is only formally monovalent. As studies have shown, all such compounds contain a group of two mercury atoms: –Hg 2 – or –Hg–Hg–. Both atoms are divalent, but one valence of each is used to form a chain, similar to the carbon chains of many organic compounds. The Hg 2+ 2 ion is unstable, and so are the compounds in which it is included, especially hydroxide and carbonate of ferrous mercury. The latter quickly decompose into Hg and HgO and, accordingly, H 2 O or CO 2.
Poison and antidote
I'm the worst death
I prefer work
in mercury mines,
where the teeth crumble in the mouth...
R. Kipling
Mercury vapor and its compounds are indeed quite toxic. Liquid mercury is dangerous primarily because of its volatility: if it is stored open in a laboratory room, a partial pressure of mercury of 0.001 mm will be created in the air. This is a lot, especially since the maximum permissible concentration of mercury in industrial premises is 0.01 mg per cubic meter of air.
The degree of toxic effect of metallic mercury is determined primarily by how much of it had time to react in the body before it was removed from there, i.e. It is not mercury itself that is dangerous, but its compounds.
Acute poisoning with mercury salts manifests itself in intestinal upset, vomiting, and swelling of the gums. A decline in cardiac activity is characteristic, the pulse becomes rare and weak, and fainting is possible. The first thing to do in such a situation is to induce vomiting in the patient. Then give him milk and egg whites. Mercury is excreted from the body mainly by the kidneys.
Chronic poisoning with mercury and its compounds results in a metallic taste in the mouth, loose gums, severe salivation, mild irritability, and weakened memory. The danger of such poisoning exists in all rooms where mercury is in contact with air. The smallest drops of spilled mercury that have clogged up under baseboards, linoleum, furniture, and in floor crevices are especially dangerous. The total surface of small mercury balls is large, and evaporation is more intense. Therefore, accidentally spilled mercury must be carefully collected. All places where the slightest droplets of liquid metal could linger must be treated with a FeCl 3 solution in order to chemically bind the mercury.
Mercury in space
Spacecraft of our time require significant amounts of electricity. Regulating the operation of engines, communications, scientific research, operation of the life support system - all this requires electricity... For now, the main sources of current are batteries and solar panels. The energy needs of spacecraft are growing and will continue to grow. Spaceships of the near future will need power plants on board. One of the options for such stations is based on a nuclear turbine generator. In many ways, it is similar to a conventional thermal power plant, but the working fluid in it is not water vapor, but mercury. It heats up its radioisotope fuel. The operating cycle of such an installation is closed: mercury steam, having passed through the turbine, condenses and returns to the boiler, where it is heated again and again sent to rotate the turbine.
Isotopes of mercury
Natural mercury consists of a mixture of seven stable isotopes with mass numbers 196, 198, 199, 200, 201, 202 and 204. The heaviest isotope is the most common: its share is almost 30%, more precisely, 29.8. The second most common isotope is mercury-200 (23.13%). And the least amount of mercury-196 is in the natural mixture - only 0.146%.
Of the radioactive isotopes of element No. 80, and there are 11 of them, only mercury-203 (half-life 46.9 days) and mercury-205 (5.5 minutes) have acquired practical significance. They are used in analytical determinations of mercury and studying its behavior in technological processes.
The largest deposits are in Europe
Mercury is one of the few metals whose largest deposits are located on the European mainland. The largest deposits of mercury are considered to be Almaden (Spain), Monte Amiata (Italy) and Idrija (Yugoslavia).
The first information about compounds containing mercury reaches us from time immemorial. Aristotle mentions it for the first time in 350 BC, but archaeological finds indicate an earlier date of use. The main areas of use of mercury were medicine, painting and architecture, the manufacture of Venetian mirrors, metal processing, etc. People found out its properties only experimentally, which required a lot of time and cost many lives. The fact that mercury is dangerous to humans has been known since its use began. Modern research methods and methods are much more effective and safer, but people still don’t know much about this metal.
Chemical element
Under normal conditions, mercury is a heavy liquid of white-silver color; its belonging to metals was proven by M.V. Lomonosov and I.A. Brown in 1759. Scientists have proven that in a solid state of aggregation it is electrically conductive and can be forged. Mercury (Hydrargyrum, Hg) in the periodic table of D.I. Mendeleev has atomic number 80, is located in the sixth period, group 2 and belongs to the zinc subgroup. Translated from Latin, the name literally means “silver water”, from Old Russian - “to roll”. The uniqueness of the element lies in the fact that it is the only one that is found in dispersed form in nature and occurs in the form of compounds. A drop of mercury rolling down a rock is an impossible phenomenon. The molar mass of the element is 200 g/mol, the atomic radius is 157 pm.
Properties
At a temperature of 20 o C, the specific gravity of mercury is 13.55 g/cm 3, for the melting process -39 o C is required, for boiling - 357 o C, for freezing -38.89 o C. The increased pressure of saturated vapors gives a high evaporation rate . As the temperature rises, mercury vapor becomes the most dangerous for living organisms, and water or any other liquid is not an obstacle to this process. The property most in demand in practice is the production of amalgam, which is formed as a result of the dissolution of a metal in mercury. When there is a large amount of it, the alloy is obtained in a semi-liquid state of aggregation. Mercury is easily released from the compound, which is used in the process of extracting precious metals from ore. Metals such as tungsten, iron, molybdenum, and vanadium cannot be amalgamated. Chemically, mercury is a fairly stable element that easily transforms into a native state and reacts with oxygen only at high temperatures (300 o C). When interacting with acids, dissolution occurs only in nitric acid and metallic mercury is oxidized by sulfur or potassium permanganate. It actively reacts with halogens (iodine, bromine, fluorine, chlorine) and non-metals (selenium, phosphorus, sulfur). Organic compounds with a carbon atom (alkylmercury) are the most stable and are formed under natural conditions. Methylmercury is considered one of the most toxic short-chain organometallic compounds. In this state, mercury becomes most dangerous to humans.
Being in nature
If we consider mercury as a mineral that is used in many industries and areas of human economic activity, then it is a rather rare metal. According to experts, the surface layer of the earth’s crust contains only 0.02% of the total amount of the mentioned element. The largest part of mercury and its compounds is found in the waters of the World Ocean and is dispersed in the atmosphere. Recent studies show that the Earth's mantle contains large amounts of this element. In accordance with this statement, such a concept as “mercury breathing of the Earth” arose. It consists in the process of degassing with further evaporation from the surface. The largest release of mercury occurs during volcanic eruptions. Subsequently, natural and man-made emissions are included in the cycle, which occurs due to combination with other elements under favorable natural conditions. The process of formation and decay of mercury vapor has been poorly studied, but the most likely hypothesis is the participation of certain types of bacteria in it. But the main problem is methyl and demethyl derivative compounds, which are actively formed in nature - in the atmosphere, water (bottom muddy areas or sectors of the greatest pollution with organic substances) - without the participation of catalysts. Methylmercury has a very high affinity to biological molecules. What is dangerous about mercury is its ability to accumulate in any living organism due to its ease of penetration and adaptation.
Place of Birth
There are more than 100 mercury-containing and mercury minerals, but the main compound that ensures the profitability of mining is cinnabar. In percentage terms, it has the following structure: sulfur 12-14%, mercury 86-88%, while native mercury, fahlores, metacinnabarite, etc. are associated with the main sulfide mineral. The dimensions of cinnabar crystals reach 3-5 cm (maximum), the most common ones are 0.1-0.3 mm in size and may contain impurities of zinc, silver, arsenic, etc. (up to 20 elements). There are about 500 ore deposits in the world; the most productive deposits are in Spain, Slovenia, Italy, and Kyrgyzstan. Two main methods are used to process ore: oxidation at high temperatures to release mercury and enrichment of the starting material with subsequent processing of the resulting concentrate.
Areas of use
Due to the fact that the danger of mercury has been proven, its use in medicine has been limited since the 70s of the 20th century. An exception is merthiolate, which is used to preserve vaccines. Silver amalgam is still found in dentistry today, but is being actively replaced by reflective fillings. The most widespread use of hazardous metal is recorded in the creation of instruments and precision instruments. Mercury vapor is used to operate fluorescent and quartz lamps. In this case, the result of the impact depends on the coating of the light-transmitting body. Due to its unique heat capacity, metallic mercury is in demand in the production of high-precision measuring instruments - thermometers. The alloys are used to make position sensors, bearings, sealed switches, electric actuators, valves, etc. Biocidal paints previously also contained mercury and were used to coat ship hulls, which prevented them from fouling. The chemical industry uses salts of this element in large quantities as a catalyst for the release of acetaldehyde. Sublimate and calomel are used to treat the seed fund - toxic mercury protects grain and seeds from pests. In metallurgy, amalgams are most in demand. Mercury compounds are often used as an electrolytic catalyst for the production of chlor alkali and active metals. Gold miners use this chemical element to process ore. Mercury and its compounds are used in jewelry, mirror production, and aluminum recycling.
Toxicity (what is dangerous about mercury)
As a result of anthropogenic human activity, the concentration of toxic substances and pollutants in our environment increases. One of these elements, ranked first in terms of toxicity, is mercury. Organic and inorganic compounds and vapors pose a danger to humans. This is a cumulative, highly toxic poison that can accumulate in the human body for years or enter at once. The central nervous system, enzymatic and hematopoietic systems are affected, and the degree and outcome of poisoning depend on the dose and route of penetration, the toxicity of the compound, and the time of exposure. Chronic mercury poisoning (accumulation of the substance in the body) is characterized by the presence of asthenovegetative syndrome and disruption of the nervous system. The first signs are: trembling of the eyelids, fingertips, and then the limbs, tongue and the whole body. With further development of poisoning, insomnia, headaches, nausea, disruption of the gastrointestinal tract, neurasthenia, and memory impairment appear. If mercury vapor poisoning occurs, the characteristic symptoms are respiratory diseases. With continuous exposure, the excretory system fails, which can lead to death.
Poisoning with mercury salts
The fastest and most complex process. Symptoms: headache, metallic taste, bleeding gums, stomatitis, increased urination with a gradual reduction and complete cessation. In severe forms, damage to the kidneys, gastrointestinal tract, and liver is typical. Even if a person survives, he will remain disabled forever. The action of mercury leads to protein precipitation and hemolysis of red blood cells. Against the background of these symptoms, irreversible damage to the central nervous system occurs. An element such as mercury poses a danger to humans in any form of interaction, and the consequences of poisoning can be irreparable: having an impact on the entire body, they can affect future generations.
Methods of penetration of poison
The main sources of poisoning are air, water, and food. Mercury can be absorbed through the respiratory tract when the substance evaporates from a surface. The skin and gastrointestinal tract have good throughput. For poisoning, it is enough to swim in a body of water that is polluted by industrial discharges containing mercury; eat foods with a high content of a chemical element that can enter them from infected biological species (fish, meat). Mercury vapor poisoning is usually obtained as a result of professional activities - when safety precautions are not observed in industries related to this element. Poisoning at home is no exception. This occurs due to improper use of devices and instruments containing mercury and its compounds.
The danger of mercury from a thermometer
The most commonly used high-precision medical instrument is a thermometer; it is found in every home. Under normal household conditions, most people do not have access to highly toxic compounds that include mercury. “The thermometer was broken” - this is the most likely situation of interaction with poison. Most of our compatriots still use mercury thermometers. This is explained primarily by the accuracy of their testimony and the population’s distrust of new technologies. If the thermometer is damaged, mercury, of course, poses a danger to humans, but illiteracy poses an even greater threat. If you quickly, efficiently and effectively carry out a series of simple manipulations, then the harm to health, if any, will be minimal.
Stage 1
First of all, you need to collect all the parts of the broken thermometer and mercury. This is the most labor-intensive process, but the health of all family members and pets depends on its implementation. For proper disposal, you must take a glass container, which must be hermetically sealed. Before starting work, all residents are removed from the premises; it is best to go outside or to another room where constant ventilation is possible. The process of collecting mercury drops cannot be performed using a vacuum cleaner or broom. The latter can crush larger metal fractions and provide a larger area for their distribution. When working with a vacuum cleaner, the danger lies in the process of heating the engine during operation, and the effect of temperature will accelerate the evaporation of particles, and after this this household appliance cannot be used for its intended purpose, it can only be disposed of.
Sequencing
- Wear a disposable medical mask, shoe covers or plastic bags on your shoes.
- Carefully inspect the place where the thermometer was broken; If there is a possibility of mercury getting on textiles, clothes, carpets, then they are hermetically packed in a garbage bag and disposed of.
- The glass parts are collected in prepared containers.
- Large drops of mercury are collected from the floor surface using a sheet of paper, a needle or knitting needles.
- Armed with a flashlight or increasing the illumination of the room, you need to expand the search for smaller particles (due to the color of the metal it is easy to find).
- Floor cracks, parquet joints, and baseboards are carefully inspected to eliminate the possibility of smaller drops getting in.
- In hard-to-reach places, mercury is collected with a syringe, which must subsequently be disposed of.
- Small drops of metal can be collected using adhesive tape or adhesive tape.
- During the entire operating time, you must go into a ventilated room or outside every 20 minutes.
- All items and improvised means used to collect mercury must be disposed of along with the contents of the thermometer.
Stage 2
After careful mechanical assembly, it is necessary to chemically treat the room. You can use potassium permanganate (potassium permanganate) - a solution of high concentration (dark color) in the amount required for the treated area. Be sure to wear new rubber gloves and a mask. All surfaces are treated with the resulting solution using a rag, and existing recesses, crevices, cracks and joints are best filled with the solution. It is better to leave the surface untouched for the next 10 hours. After the specified time, the potassium permanganate solution is washed off with clean water, then cleaning is carried out using detergents throughout the entire apartment. For the next 6-7 days, be sure to carry out regular ventilation of the room and daily wet cleaning. To make sure there is no mercury, you can invite specialists with special equipment from epidemiology centers.
Treatment methods for intoxication
WHO identifies 8 of the most dangerous substances, the content of which in the atmosphere, food and water must be carefully monitored due to their danger to human life and health. These are lead, cadmium, arsenic, tin, iron, copper, zinc and, of course, mercury. The hazard class of these elements is very high, and the consequences of poisoning with them cannot be completely stopped. The basis of treatment is to protect the person from further contact with the poison. In mild and non-chronic cases of mercury poisoning, it is excreted from the body in feces, urine, and sweat. The toxic dose is 0.4 ml, lethal - from 100 mg. If you suspect an interaction with poison, you should contact a specialist who, based on test results, will determine the degree of intoxication and prescribe therapy.
The extraction of mercury at all times has not been without losses for humanity. This is a metal that is hazardous to health and causes poisoning to the entire body. In industrial production, mercury is irreplaceable - it is the only liquid metal.
But there has always been interest in it, especially among artisans in Central Asia. It was here that the first mercury mines appeared in the 6th-4th centuries BC.
Where is mercury found?
The metal is found in a mineral called cinnabar, a red stone used since ancient times as a natural and high-quality dye. Mercury is also found in other mineral formations (about 20 names), but they contain little of this rare metal.
Features of mercury deposits
Mercury is indispensable in industrial production because it is the only liquid metal. There is no other such substance in a fluid form at a standard temperature with properties characteristic of metals. Therefore, its value is high and the search for cinnabar deposits is being carried out in all countries. From ancient China and India, belief in the healing properties of this substance has come to this day. There it was considered dragon blood and the silvery metal obtained from it was given sacred qualities. Over time, its healing properties have been confirmed by science. In all centuries, alchemists tried to obtain gold from a combination of mercury and sulfur; this significantly increased the value of the metal.
Related materials:
How is salt obtained?
How to obtain mercury
Cinnabar contains more than 85% mercury sulfide; geologists do not know of any other mineral rich in minerals. Mineral conglomerates occur as granular or diamond-shaped fragments in rocks that occur at shallow depths. Mercury bodies are found in quartzite, dolomite and shale deposits. Mercury is isolated from the ore by heating, in which case it flows out of the rock formations in small drops, which are collected in special protected containers.
Mercury is the only metal known to man that remains liquid at room temperature. Externally, mercury resembles liquid silver; when it hits a flat surface, a drop of mercury instantly crumbles into hundreds of tiny balls, which seem to repel each other and scatter in different directions.
Mercury is a very rare element. In general, in nature, mercury is formed during the oxidation of cinnabar and the decomposition of the resulting sulfate; during ; by isolation from aqueous solutions. Mercury is dispersed in the earth's crust, and as a result of precipitation from hot underground waters, it forms mercury ores.
To date, 35 mercury-containing minerals are known. Some mercury is found in seawater, shales and clays.
From the history of the issue
Already two thousand years BC in Ancient India and Ancient China they knew how to mine native mercury. Mercury containing cinnabar was already used in treatment and cosmetology. During the experiments of ancient scientists, heated cinnabar settled on the metal in the form of “liquid silver”. 
Alchemists attached great importance to mercury - it was believed that after mercury hardens, it can turn into gold. For the first time, Lomonosov managed to obtain solid mercury - he used a mixture of snow and concentrated nitric acid for this.
Where is mercury used?
Mercury is indispensable in the manufacture of various metrological instruments - thermometers, polarographs, vacuum pumps. Mercury is an important element in the production of mercury lamps and rectifiers. In addition, this metal is actively used in the chemical industry and metallurgy.
Mercury is a catalyst in various reactions and an important element in the amalgamation of other metals. It is used in medicine, industry and agriculture. It is the mercury coating that allows us to produce mirrors, which we cannot do without.
Basic properties of mercury
It is a silvery, heavy, liquid metal that evaporates at room temperature. The higher the air temperature, the faster evaporation occurs. Mercury (chemical formula Hg) interacts with silver, gold, zinc, wetting them and forming amalgams. Mercury boils at a temperature of +357.25 C. 
According to the degree of danger, it belongs to the first class and is an extremely powerful pollutant of the environment - air, soil, water. Mercury and its compounds are extremely toxic and dangerous to the human body.
The dangers of mercury
Entering the body through the lungs, mercury vapor causes acute and chronic poisoning. Mercury affects the respiratory system, liver, central nervous system, gastrointestinal tract, cardiovascular system, and other internal organs. Symptoms of toxic damage appear within 8-24 hours.
The victim experiences weakness, apathy, emotional instability, dizziness, and headache. Attention and memory weaken, sweating appears, pain when swallowing, the temperature rises, stomach pain begins, nausea, vomiting, the temperature rises, and hand tremors appear.
In case of serious poisoning, death cannot be ruled out. Mercury enters the body most often through the lungs - a person inhales dangerous fumes that have no odor.
Precautions and storage methods
When working with mercury, you need to use gas masks or filtering respirators. If mercury contamination occurs, demercurization measures are taken. Visible amounts of metallic mercury are removed from contaminated surfaces, after which chemical treatment is carried out using chemical reagents. 
Mercury used in industry is stored in steel cylinders with a capacity of no more than 35 kg, in ceramic or glass cylinders with a capacity of 500 ml with thick walls, a metal corrugated stopper with a plastic gasket. Each cylinder contains 5 kg of mercury.
In laboratories, mercury is stored in sealed glass ampoules of 30-40 ml each, which are lowered into welded steel boxes. Mercury cannot be stored in open containers, as well as in bottles, flasks and other chemical containers with thin walls.
