Who discovered arsenic. What is arsenic? Definition, formula, properties
Some who died in the Middle Ages from cholera did not die from it. The symptoms of the disease are similar to those arsenic poisoning.
Having learned this, medieval businessmen began to offer element trioxide as a poison. Substance. The lethal dose is only 60 grams.
They were divided into portions, giving for several weeks. In the end, no one suspected that the man did not die from cholera.
Arsenic taste is not felt in small doses, being, for example, in food or drinks. In modern realities, of course, there is no cholera.
People do not have to be afraid of arsenic. More likely, mice need to be afraid. A toxic substance is a type of poison for rodents.
In their honor, by the way, the element is named. The word "arsenic" exists only in Russian-speaking countries. The official name of the substance is arsenicum.
Designation in - As. The serial number is 33. Based on it, we can assume a complete list of the properties of arsenic. But let's not assume. Let's look into the matter for sure.
Properties of arsenic
The Latin name of the element is translated as "strong". Apparently, this refers to the effect of the substance on the body.
With intoxication, vomiting begins, digestion is upset, the stomach twists and the work of the nervous system is partially blocked. not one of the weak.
Poisoning occurs from any of the allotropic forms of the substance. Alltropy is the existence of manifestations of the same thing that are different in structure and properties. element. Arsenic most stable in metallic form.
Rhombohedral steel gray brittle. The units have a characteristic metallic, but from contact with moist air, they dim.
Arsenic - metal, whose density is almost 6 grams per cubic centimeter. For other forms of the element, the indicator is less.
In second place is amorphous arsenic. Element characteristic: — almost black color.
The density of this form is 4.7 grams per cubic centimeter. Outwardly, the material resembles.
The usual state of arsenic for the inhabitants is yellow. Cubic crystallization is unstable, it becomes amorphous when heated to 280 degrees Celsius, or under the action of simple light.
Therefore, yellows are soft, like in the dark. Despite the color, the aggregates are transparent.
From a number of modifications of the element, it can be seen that it is only half the metal. The obvious answer to the question is:- " Arsenic metal or non-metal", No.
Chemical reactions serve as confirmation. The 33rd element is acid-forming. However, being in acid itself does not give.
Metals do things differently. In the case of arsenic, they are not obtained even upon contact with, one of the strongest.
Salt-like compounds are "born" during the reactions of arsenic with active metals.
I mean oxidizers. The 33rd substance interacts only with them. If the partner does not have pronounced oxidizing properties, the interaction will not take place.
This applies even to alkalis. That is, arsenic is a chemical element pretty inert. How, then, to get it, if the list of reactions is very limited?
Arsenic mining
Arsenic is mined along with other metals. Separate them, the 33rd substance remains.
In nature there are compounds of arsenic with other elements. It is from them that the 33rd metal is extracted.
The process is profitable, since, together with arsenic, they often go,, and.
It is found in granular masses, or cubic crystals of tin color. Sometimes, there is a yellow tint.
Arsenic compound and metal ferrum has a "brother", in which instead of the 33rd substance is . It is an ordinary golden-colored pyrite.
The aggregates are similar to arsenoversion, but they cannot serve as arsenic ore, although they also contain it as an impurity.
Arsenic in the usual, by the way, also happens, but, again, as an impurity.
The amount of element per ton is so small, but even secondary extraction does not make sense.
If you evenly distribute the world's reserves of arsenic in the earth's crust, you get only 5 grams per ton.
So, the element is not common, it is comparable in number to , , .
If you look at the metals with which arsenic forms minerals, then this is not only, but also with cobalt and nickel.
The total number of minerals of the 33rd element reaches 200. There is also a native form of matter.
Its presence is explained by the chemical inertness of arsenic. Formed next to elements with which reactions are not provided, the hero remains in splendid isolation.
In this case, often, needle-shaped, or cubic aggregates are obtained. Usually, they grow together.
Application of arsenic
The element arsenic belongs to dual, not only showing the properties of both metal and non-metal.
The perception of the element by humanity is also dual. In Europe, the 33rd substance has always been considered a poison.
In 1733, they even issued a decree prohibiting the sale and purchase of arsenic.
In Asia, the "poison" has been used by physicians for 2000 years in the treatment of psoriasis and syphilis.
Modern doctors have proven that the 33rd element attacks proteins that provoke oncology.
In the 20th century, some European doctors also sided with the Asians. In 1906, for example, Western pharmacists invented the drug salvarsan.
He became the first in official medicine, was used against a number of infectious diseases.
True, immunity is developed to the drug, as well as to any constant intake of arsenic in small doses.
Effective 1-2 courses of the drug. If immunity is formed, people can take a lethal dose of the element and stay alive.
In addition to physicians, metallurgists became interested in the 33rd element, starting to add in for the production of shots.
It is done on the basis of which is included in heavy metals. Arsenic increases the lead and allows its splashes to take on a spherical shape when cast. It is correct, which improves the quality of the shot.
Arsenic can also be found in thermometers, or rather them. It is called Viennese, mixed with the oxide of the 33rd substance.
The connection serves as a clarifier. Arsenic was also used by glassblowers of antiquity, but as a matting additive.
Opaque glass becomes with an impressive impurity of a toxic element.
Keeping proportions, many glassblowers fell ill and died prematurely.
And tanneries use sulfides arsenic.
Element main subgroups The 5th group of the periodic table is part of some paints. In the leather industry, arsenicum helps to remove hair from.
Arsenic price
Pure arsenic is most often offered in metallic form. Prices are set per kilogram, or ton.
1000 grams costs about 70 rubles. For metallurgists, they offer ready-made, for example, arsenic with copper.
In this case, they take 1500-1900 rubles per kilo. Kilograms sell and arsenic anhydrite.
It is used as a skin medicine. The agent is necrotic, that is, it dies the affected area, killing not only the causative agent of the disease, but also the cells themselves. The method is radical, but effective.
The content of the article
ARSENIC- a chemical element of group V of the periodic table, belongs to the nitrogen family. Relative atomic mass 74.9216. In nature, arsenic is represented by only one stable nuclide, 75 As. More than ten of its radioactive isotopes with a half-life from several minutes to several months have also been artificially obtained. Typical oxidation states in compounds are –3, +3, +5. The name of arsenic in Russian is associated with the use of its compounds for the extermination of mice and rats; The Latin name Arsenicum comes from the Greek "Arsen" - strong, powerful.
Historical information.
Arsenic belongs to the five "alchemical" elements discovered in the Middle Ages (surprisingly, four of them - As, Sb, Bi and P are in the same group of the periodic table - the fifth). At the same time, arsenic compounds have been known since ancient times, they were used for the production of paints and medicines. Of particular interest is the use of arsenic in metallurgy.
Several millennia ago, the Stone Age gave way to the Bronze Age. Bronze is an alloy of copper and tin. Historians believe that the first bronze was cast in the Tigris and Euphrates valley, sometime between the 30th and 25th centuries. BC. In some regions, bronze was smelted with especially valuable properties - it was better cast and easier to forge. As modern scientists have found out, it was a copper alloy containing from 1 to 7% arsenic and no more than 3% tin. Probably, at first, during its smelting, the rich copper ore malachite was confused with the weathering products of some also green sulfide copper-arsenic minerals. Having appreciated the remarkable properties of the alloy, the ancient craftsmen then specifically looked for arsenic minerals. For searches, they used the property of such minerals to give a specific garlic smell when heated. However, over time, the smelting of arsenic bronze ceased. Most likely this happened due to frequent poisoning during the firing of arsenic-containing minerals.
Of course, arsenic was known in the distant past only in the form of its minerals. So, in ancient China, the solid mineral realgar (sulfide composition As 4 S 4, realgar in Arabic means “mine dust”) was used for stone carving, however, when heated or exposed to light, it “spoiled”, as it turned into As 2 S 3 . In the 4th c. BC. Aristotle described this mineral under the name "sandarak". In the 1st century AD the Roman writer and scientist Pliny the Elder, and the Roman physician and botanist Dioscorides described the mineral orpiment (arsenic sulfide As 2 S 3). Translated from Latin, the name of the mineral means "golden paint": it was used as a yellow dye. In the 11th century alchemists distinguished three "varieties" of arsenic: the so-called white arsenic (oxide As 2 O 3), yellow arsenic (sulfide As 2 S 3) and red arsenic (sulfide As 4 S 4). White arsenic was obtained by sublimation of arsenic impurities during the roasting of copper ores containing this element. Condensing from the gas phase, arsenic oxide precipitated in the form of a white deposit. White arsenic has been used since ancient times to kill pests, as well as...
In the 13th century Albert von Bolstedt (Albert the Great) obtained a metal-like substance by heating yellow arsenic with soap; this may have been the first sample of arsenic in the form of a simple substance, obtained artificially. But this substance broke the mystical "connection" of the seven known metals with the seven planets; this is probably why the alchemists considered arsenic an "illegitimate metal". At the same time, they discovered its property to give copper a white color, which gave reason to call it "a means that whitens Venus (that is, copper)."
Arsenic was unequivocally identified as an individual substance in the middle of the 17th century, when the German pharmacist Johann Schroeder obtained it in a relatively pure form by reducing the oxide with charcoal. Later, the French chemist and physician Nicolas Lemery obtained arsenic by heating a mixture of its oxide with soap and potash. In the 18th century arsenic was already well known as an unusual "semi-metal". In 1775 the Swedish chemist K.V. Scheele obtained arsenic acid and gaseous arsenic hydrogen, and in 1789 A.L. Lavoisier finally recognized arsenic as an independent chemical element. In the 19th century organic compounds containing arsenic were discovered.
Arsenic in nature.
There is little arsenic in the earth's crust - about 5 10 -4% (that is, 5 g per ton), about the same as germanium, tin, molybdenum, tungsten or bromine. Often arsenic in minerals occurs together with iron, copper, cobalt, nickel.
The composition of the minerals formed by arsenic (and there are about 200 of them) reflects the "semi-metallic" properties of this element, which can be in both positive and negative oxidation states and combine with many elements; in the first case, arsenic can play the role of a metal (for example, in sulfides), in the second - a non-metal (for example, in arsenides). The complex composition of a number of arsenic minerals reflects its ability, on the one hand, to partially replace sulfur and antimony atoms in the crystal lattice (the ionic radii S -2, Sb -3 and As -3 are close and amount to 0.182, 0.208 and 0.191 nm, respectively), on the other hand are metal atoms. In the first case, arsenic atoms have rather a negative oxidation state, in the second - a positive one.
The electronegativity of arsenic (2.0) is low, but higher than that of antimony (1.9) and most metals; therefore, the oxidation state –3 is observed for arsenic only in metal arsenides, as well as in SbAs stibarsen and intergrowths of this mineral with pure crystals. antimony or arsenic (the mineral allemontite). Many compounds of arsenic with metals, judging by their composition, are related to intermetallic compounds rather than arsenides; some of them are characterized by a variable content of arsenic. In arsenides, several metals can be present simultaneously, the atoms of which, at a close ion radius, replace each other in the crystal lattice in arbitrary ratios; in such cases, in the mineral formula, the symbols of the elements are listed separated by commas. All arsenides have a metallic luster, they are opaque, heavy minerals, their hardness is low.
An example of natural arsenides (about 25 of them are known) are the minerals löllingite FeAs 2 (an analogue of pyrite FeS 2), skutterudite CoAs 2–3 and nickelskutterudite NiAs 2–3, nickeline (red nickel pyrite) NiAs, rammelsbergite (white nickel pyrite) NiAs 2 , safflorite (speis cobalt) CoAs 2 and clinosafflorite (Co,Fe,Ni)As 2, langisite (Co,Ni)As, sperrylite PtAs 2, maucherite Ni 11 As 8, oregonite Ni 2 FeAs 2, algodonite Cu 6 As. Due to their high density (more than 7 g/cm3), geologists refer many of them to the group of "super-heavy" minerals.
The most common arsenic mineral is arsenopyrite (arsenic pyrite) FeAsS can be considered as a product of the replacement of sulfur in pyrite FeS 2 by arsenic atoms (ordinary pyrite also always contains some arsenic). Such compounds are called sulfosalts. The minerals cobaltite (cobalt luster) CoAsS, glaucodot (Co,Fe)AsS, gersdorfite (nickel luster) NiAsS, enargite and lusonite of the same composition, but different structure Cu 3 AsS 4 , proustite Ag 3 AsS 3 - an important silver ore, were formed similarly. sometimes called "ruby silver" because of its bright red color, it is often found in the upper layers of silver veins, where magnificent large crystals of this mineral are found. Sulfosalts may also contain noble metals of the platinum group; these minerals are osarsite (Os,Ru)AsS, ruarsite RuAsS, irarsite (Ir,Ru,Rh,Pt)AsS, platarsite (Pt,Rh,Ru)AsS, hollingworthite (Rd,Pt,Pd)AsS. Sometimes the role of sulfur atoms in such double arsenides is played by antimony atoms, for example, in seinjayokite (Fe,Ni)(Sb,As) 2, arsenopalladinite Pd 8 (As,Sb) 3, arsenepolybasite (Ag,Cu) 16 (Ar,Sb) 2 S 11 .
The structure of minerals is interesting, in which arsenic is present simultaneously with sulfur, but rather plays the role of a metal, grouping together with other metals. These are the minerals arsenosulvanite Cu 3 (As,V)S 4 , arsenohauchecornite Ni 9 BiAsS 8 , freibergite (Ag,Cu,Fe) 12 (Sb,As) 4 S 13 , tennantite (Cu,Fe) 12 As 4 S 13 , argentotennantite (Ag,Cu) 10 (Zn,Fe) 2 (As,Sb) 4 S 13, goldfieldite Cu 12 (Te,Sb,As) 4 S 13, girodite (Cu,Zn,Ag) 12 (As,Sb) 4 (Se,S) 13 . One can imagine what a complex structure the crystal lattice of all these minerals has.
Arsenic has a clearly positive oxidation state in natural sulfides - yellow orpiment As 2 S 3, orange-yellow dimorphite As 4 S 3, orange-red realgar As 4 S 4, carmine-red getchellite AsSbS 3, and also in colorless oxide As 2 O 3, which occurs as minerals arsenolite and claudetite with different crystal structures (they are formed as a result of weathering of other arsenic minerals). These minerals usually occur as small inclusions. But in the 30s of the 20th century. in the southern part of the Verkhoyansk Range, huge crystals of orpiment up to 60 cm in size and weighing up to 30 kg were found.
In natural salts of arsenic acid H 3 AsO 4 - arsenates (about 90 of them are known), the oxidation state of arsenic is +5; examples are bright pink erythrin (cobalt color) Co 3 (AsO 4) 2 8H 2 O, green annabergite Ni 3 (AsO 4) 2 8H 2 O, scorodite Fe III AsO 4 2H 2 O and simplesite Fe II 3 (AsO 4) 2 8H 2 O, brown-red gasparite (Ce, La, Nd) ArO 4, colorless gernesite Mg 3 (AsO 4) 2 8H 2 O, rooseveltite BiAsO 4 and kettigite Zn 3 (AsO 4) 2 8H 2 O, as well as many basic salts, for example, olivenite Cu 2 AsO 4 (OH), arsenobismite Bi 2 (AsO 4) (OH) 3. But natural arsenites - derivatives of arsenous acid H 3 AsO 3 are very rare.
In central Sweden, there are the famous Langban iron-manganese quarries, in which more than 50 samples of minerals representing arsenates have been found and described. Some of them are not found anywhere else. They were once formed as a result of the reaction of arsenic acid H 3 AsO 4 with pyrocroite Mn (OH) 2 at not very high temperatures. Usually, arsenates are products of the oxidation of sulfide ores. They usually do not have industrial applications, but some of them are very beautiful and adorn mineralogical collections.
In the names of numerous arsenic minerals one can find toponyms (Lölling in Austria, Freiberg in Saxony, Seinäjoki in Finland, Skutterud in Norway, Allemon in France, the Canadian Langis mine and the Getchell mine in Nevada, Oregon in the USA, etc.), the names of geologists, chemists, politicians, etc. (German chemist Karl Rammelsberg, Munich mineral merchant William Maucher, mine owner Johann von Gersdorff, French chemist F. Claude, English chemists John Proust and Smithson Tennant, Canadian chemist F. L. Sperry, US President Roosevelt, etc.), plant names (for example, the name of the mineral safflorite comes from saffron), the initial letters of the names of the elements - arsenic, osmium, ruthenium, iridium, palladium, platinum, Greek roots ("erythros" - red, "enargon" - visible, "lithos" - stone) and etc. etc.
An interesting ancient name for the mineral nickeline (NiAs) is kupfernickel. Medieval German miners called Nickel the evil mountain spirit, and Kupfernickel (Kupfernickel, from German Kupfer - copper) - "damn copper", "fake copper". The copper-red crystals of this ore looked very much like copper ore; it was used in glass making to color glass green. But no one could get copper from it. This ore was studied by the Swedish mineralogist Axel Kronstedt in 1751 and isolated a new metal from it, calling it nickel.
Since arsenic is chemically quite inert, it is also found in its native state - in the form of fused needles or cubes. Such arsenic usually contains from 2 to 16% impurities - most often it is Sb, Bi, Ag, Fe, Ni, Co. It is easy to grind into powder. In Russia, native arsenic was found by geologists in Transbaikalia, in the Amur Region, and it is also found in other countries.
Arsenic is unique in that it is found everywhere - in minerals, rocks, soil, water, plants and animals, it is not for nothing that it is called "ubiquitous". The distribution of arsenic over different regions of the globe was largely determined in the processes of formation of the lithosphere by the volatility of its compounds at high temperatures, as well as by the processes of sorption and desorption in soils and sedimentary rocks. Arsenic migrates easily, which is facilitated by the rather high solubility of some of its compounds in water. In humid climates, arsenic is washed out of the soil and carried away by groundwater and then by rivers. The average content of arsenic in rivers is 3 µg/l, in surface waters - about 10 µg/l, in the water of the seas and oceans - only about 1 µg/l. This is due to the relatively rapid precipitation of its compounds from water with accumulation in bottom sediments, for example, in ferromanganese nodules.
In soils, the arsenic content is usually between 0.1 and 40 mg/kg. But in the area of occurrence of arsenic ores, as well as in volcanic regions, the soil can contain a lot of arsenic - up to 8 g / kg, as in some areas of Switzerland and New Zealand. In such places, vegetation dies, and animals get sick. This is typical for steppes and deserts, where arsenic is not washed out of the soil. Clay rocks are also enriched in comparison with the average content - they contain four times more arsenic than the average. In our country, the maximum allowable concentration of arsenic in the soil is 2 mg/kg.
Arsenic can be removed from the soil not only by water, but also by wind. But for this, it must first turn into volatile organoarsenic compounds. This transformation occurs as a result of the so-called biomethylation - the addition of a methyl group with the formation of a C–As bond; this enzymatic process (it is well known for mercury compounds) occurs with the participation of the coenzyme methylcobalamin, a methylated derivative of vitamin B 12 (it is also found in the human body). Biomethylation of arsenic occurs both in fresh and sea water and leads to the formation of organoarsenic compounds - methylarsonic acid CH 3 AsO (OH) 2, dimethylarsine (dimethylarsenic, or cacodylic) acid (CH 3) 2 As (O)OH, trimethylarsine ( CH 3) 3 As and its oxide (CH 3) 3 As = O, which are also found in nature. Using 14 C-labeled methylcobalamin and 74 As-labeled sodium hydrogen arsenate Na 2 HAsO 4, it was shown that one of the methanobacteria strains reduces and methylates this salt to volatile dimethylarsine. As a result, the air in rural areas contains an average of 0.001 - 0.01 μg / m 3 arsenic, in cities where there are no specific pollution - up to 0.03 μg / m 3, and near sources of pollution (non-ferrous metal smelting plants, power plants, working on coal with a high content of arsenic, etc.) the concentration of arsenic in the air can exceed 1 µg/m 3 . The intensity of arsenic fallout in the areas of industrial centers is 40 kg/km 2 per year.
The formation of volatile compounds of arsenic (trimethylarsine, for example, boils at only 51 ° C) caused in the 19th century. numerous poisonings, since arsenic was contained in plaster and even in green wallpaper paint. In the form of paint, Scheele greens Cu 3 (AsO 3) 2 were used earlier. n H 2 O and Parisian or Schweifurt greens Cu 4 (AsO 2) 6 (CH 3 COO) 2. In conditions of high humidity and the appearance of mold, volatile organoarsenic derivatives are formed from such paint. It is believed that this process could be the cause of Napoleon's slow poisoning in the last years of his life (as is known, arsenic was found in Napoleon's hair a century and a half after his death).
Arsenic is found in significant amounts in some mineral waters. Russian standards establish that arsenic in medicinal table mineral waters should not exceed 700 µg/l. AT Jermuk it may be several times larger. Drinking one or two glasses of “arsenic” mineral water will not bring harm to a person: in order to be fatally poisoned, you need to drink three hundred liters at once ... But it is clear that you cannot drink such water all the time instead of ordinary water.
Chemists have found that arsenic in natural waters can be found in different forms, which is significant in terms of its analysis, migration methods, and different toxicity of these compounds; thus, trivalent arsenic compounds are 25–60 times more toxic than pentavalent ones. As(III) compounds in water are usually present in the form of weak arsenic acid H 3 AsO 3 ( RK a = 9.22), while the As(V) compounds are in the form of a much stronger arsenic acid H 3 AsO 4 ( RK a = 2.20) and its deprotonated anions H 2 AsO 4 – and HAsO 4 2–.
The living matter of arsenic contains on average 6 10 -6%, that is, 6 μg / kg. Some seaweeds are able to concentrate arsenic to such an extent that they become dangerous to humans. Moreover, these algae can grow and multiply in pure solutions of arsenic acid. Such algae are used in some Asian countries as a remedy for rats. Even in the clear waters of the Norwegian fjords, algae can contain up to 0.1 g/kg of arsenic. In humans, arsenic is found in brain tissue and muscles, it accumulates in hair and nails.
Arsenic properties.
Although in appearance arsenic resembles a metal, it is still rather a non-metal: it does not form salts, for example, with sulfuric acid, but is itself an acid-forming element. Therefore, this element is often called a semimetal. Arsenic exists in several allotropic forms and in this respect closely resembles phosphorus. The most stable of them is gray arsenic, a very fragile substance that has a metallic sheen when freshly fractured (hence the name "metallic arsenic"); its density is 5.78 g/cm 3 . With strong heating (up to 615 ° C), it sublimates without melting (the same behavior is typical for iodine). Under a pressure of 3.7 MPa (37 atm), arsenic melts at 817°C, which is much higher than the sublimation temperature. The electrical conductivity of gray arsenic is 17 times less than that of copper, but 3.6 times higher than that of mercury. With increasing temperature, its electrical conductivity, like that of typical metals, decreases - approximately to the same extent as that of copper.
If arsenic vapor is cooled very quickly to the temperature of liquid nitrogen (-196 ° C), a transparent soft yellow substance is obtained, resembling yellow phosphorus, its density (2.03 g / cm 3) is much lower than that of gray arsenic. Pairs of arsenic and yellow arsenic consist of As 4 molecules that have the shape of a tetrahedron - and here the analogy with phosphorus. At 800°C, a noticeable dissociation of vapor begins with the formation of As 2 dimers, while at 1700°C only As 2 molecules remain. When heated and under the action of ultraviolet, yellow arsenic quickly turns into gray with heat release. When arsenic vapor condenses in an inert atmosphere, another amorphous black form of this element is formed. If arsenic vapor is deposited on glass, a mirror film is formed.
The structure of the outer electron shell of arsenic is the same as that of nitrogen and phosphorus, but unlike them, it has 18 electrons in the penultimate shell. Like phosphorus, it can form three covalent bonds (configuration 4s 2 4p 3), leaving an lone pair on the As atom. The sign of the charge on the As atom in compounds with covalent bonds depends on the electronegativity of neighboring atoms. The participation of the lone pair in the complex formation is much more difficult for arsenic than for nitrogen and phosphorus.
If d orbitals are involved in the As atom, the 4s electrons can be depaired to form five covalent bonds. This possibility is practically realized only in combination with fluorine - in pentafluoride AsF 5 (pentachloryl AsCl 5 is also known, but it is extremely unstable and quickly decomposes even at –50 ° C).
In dry air, arsenic is stable, but in humid air it tarnishes and becomes covered with black oxide. During sublimation, arsenic vapor easily burns in air with a blue flame to form heavy white vapors of arsenic anhydride As 2 O 3 . This oxide is one of the most common arsenic-containing reagents. It has amphoteric properties:
As 2 O 3 + 6HCl ® 2AsCl 3 + 3H 2 O,
2 O 3 + 6NH 4 OH ® 2 (NH 4) 3 AsO 3 + 3H 2 O.
When As 2 O 3 is oxidized, an acid oxide is formed - arsenic anhydride:
As 2 O 3 + 2HNO 3 ® As 2 O 5 + H 2 O + NO 2 + NO.
When it interacts with soda, sodium hydrogen arsenate is obtained, which is used in medicine:
As 2 O 3 + 2Na 2 CO 3 + H 2 O ® 2Na 2 HAsO 4 + 2CO 2.
Pure arsenic is rather inert; water, alkalis and acids that do not have oxidizing properties do not act on it. Dilute nitric acid oxidizes it to ortho-arsenic acid H 3 AsO 3, and concentrated - to ortho-arsenic H 3 AsO 4:
3As + 5HNO 3 + 2H 2 O ® 3H 3 AsO 4 + 5NO.
Arsenic(III) oxide reacts similarly:
3As 2 O 3 + 4HNO 3 + 7H 2 O ® 6H 3 AsO 4 + 4NO.
Arsenic acid is an acid of medium strength, slightly weaker than phosphoric. In contrast, arsenic acid is very weak, corresponding in strength to boric acid H 3 BO 3. In its solutions, there is an equilibrium H 3 AsO 3 HAsO 2 + H 2 O. Arsenic acid and its salts (arsenites) are strong reducing agents:
HAsO 2 + I 2 + 2H 2 O ® H 3 AsO 4 + 2HI.
Arsenic reacts with halogens and sulfur. AsCl 3 chloride is a colorless oily liquid fuming in air; hydrolyzes with water: AsCl 3 + 2H 2 O ® HAsO 2 + 3HCl. Bromide AsBr 3 and iodide AsI 3 are known, which are also decomposed by water. In the reactions of arsenic with sulfur, sulfides of various compositions are formed - up to Ar 2 S 5. Arsenic sulfides dissolve in alkalis, in a solution of ammonium sulfide and in concentrated nitric acid, for example:
As 2 S 3 + 6KOH ® K 3 AsO 3 + K 3 AsS 3 + 3H 2 O,
2 S 3 + 3 (NH 4) 2 S ® 2 (NH 4) 3 AsS 3,
2 S 5 + 3 (NH 4) 2 S ® 2 (NH 4) 3 AsS 4,
As 2 S 5 + 40HNO 3 + 4H 2 O ® 6H 2 AsO 4 + 15H 2 SO 4 + 40NO.
In these reactions, thioarsenites and thioarsenates are formed - salts of the corresponding thioacids (similar to thiosulfuric acid).
In the reaction of arsenic with active metals, salt-like arsenides are formed, which are hydrolyzed by water. The reaction proceeds especially quickly in an acidic medium with the formation of arsine: Ca 3 As 2 + 6HCl ® 3CaCl 2 + 2AsH 3. Arsenides of low-active metals - GaAs, InAs, etc. have a diamond-like atomic lattice. Arsine is a colorless, odorless, highly poisonous gas, but impurities give it the smell of garlic. Arsine slowly decomposes into elements already at room temperature and quickly when heated.
Arsenic forms many organoarsenic compounds, for example, tetramethyldiarsine (CH 3) 2 As–As(CH 3) 2 . As early as 1760, the director of the Servian porcelain factory, Louis Claude Cade de Gassicourt, distilling potassium acetate with arsenic (III) oxide, unexpectedly obtained a smoking liquid containing arsenic with a disgusting smell, which was called alarsin, or Cade liquid. As it turned out later, this liquid contained the first obtained organic derivatives of arsenic: the so-called cacodyl oxide, which was formed as a result of the reaction
4CH 3 COOK + As 2 O 3 ® (CH 3) 2 As–O–As(CH 3) 2 + 2K 2 CO 3 + 2CO 2 , and dicacodyl (CH 3) 2 As–As(CH 3) 2 . Kakodil (from the Greek "kakos" - bad) was one of the first radicals discovered in organic compounds.
In 1854, the Parisian professor of chemistry Auguste Kaur synthesized trimethylarsine by the action of methyl iodide on sodium arsenide: 3CH 3 I + AsNa 3 ® (CH 3) 3 As + 3NaI.
Subsequently, arsenic trichloride was used for syntheses, for example,
(CH 3) 2 Zn + 2AsCl 3 ® 2(CH 3) 3 As + 3ZnCl 2 .
In 1882, aromatic arsines were obtained by the action of metallic sodium on a mixture of aryl halides and arsenic trichloride: 3C 6 H 5 Cl + AsCl 3 + 6Na ® (C 6 H 5) 3 As + 6NaCl. The chemistry of organic derivatives of arsenic developed most intensively in the 20s of the 20th century, when some of them had antimicrobial, as well as irritating and blistering effects. At present, tens of thousands of organoarsenic compounds have been synthesized.
Getting arsenic.
Arsenic is obtained mainly as a by-product of the processing of copper, lead, zinc and cobalt ores, as well as gold mining. Some polymetallic ores contain up to 12% arsenic. When such ores are heated to 650–700°C in the absence of air, arsenic sublimates, and when heated in air, volatile oxide As 2 O 3, “white arsenic,” is formed. It is condensed and heated with coal, and arsenic is reduced. Obtaining arsenic is a harmful production. Previously, when the word "ecology" was known only to narrow specialists, "white arsenic" was released into the atmosphere, and it settled in neighboring fields and forests. The exhaust gases of arsenic plants contain between 20 and 250 mg/m 3 of As 2 O 3 , while the air usually contains about 0.00001 mg/m 3 . The average daily allowable concentration of arsenic in the air is considered to be only 0.003 mg / m 3. Paradoxically, even now it is not the plants for its production that pollute the environment with arsenic, but non-ferrous metallurgy enterprises and power plants that burn coal. Bottom sediments near copper smelters contain a huge amount of arsenic - up to 10 g/kg. Arsenic can also get into the soil with phosphate fertilizers.
And another paradox: they get more arsenic than they need; this is a rather rare occurrence. In Sweden, "unnecessary" arsenic was even forced to be buried in reinforced concrete containers in deep abandoned mines.
The main industrial mineral of arsenic is arsenopyrite FeAsS. There are large copper-arsenic deposits in Georgia, Central Asia and Kazakhstan, in the USA, Sweden, Norway and Japan, arsenic-cobalt deposits in Canada, arsenic-tin deposits in Bolivia and England. In addition, gold-arsenic deposits are known in the USA and France. Russia has numerous deposits of arsenic in Yakutia, the Urals, Siberia, Transbaikalia and Chukotka.
Definition of arsenic.
A qualitative reaction to arsenic is the precipitation of yellow sulfide As 2 S 3 from hydrochloric acid solutions. Traces are determined by the Marsh reaction or the Gutzeit method: strips of paper moistened with HgCl 2 darken in the presence of arsine, which reduces sublimate to mercury.
In recent decades, various sensitive methods of analysis have been developed, with which it is possible to quantify negligible concentrations of arsenic, for example, in natural waters. These include flame atomic absorption spectrometry, atomic emission spectrometry, mass spectrometry, atomic fluorescence spectrometry, neutron activation analysis... If there is very little arsenic in the water, pre-concentration of the samples may be required. Using this concentration, a group of Kharkov scientists from the National Academy of Sciences of Ukraine developed in 1999 an X-ray extraction method for the determination of arsenic (as well as selenium) in drinking water with a sensitivity of up to 2.5–5 µg/l.
For the separate determination of As(III) and As(V) compounds, they are first separated from each other using well-known extraction and chromatographic methods, as well as using selective hydrogenation. The extraction is usually carried out with sodium dithiocarbamate or ammonium pyrrolidine dithiocarbamate. These compounds form water-insoluble complexes with As(III), which can be extracted with chloroform. The arsenic can then be brought back into the aqueous phase by oxidation with nitric acid. In the second sample, arsenate is converted to arsenite with the help of a reducing agent, and then a similar extraction is performed. This is how “total arsenic” is determined, and then As (III) and As (V) are determined separately by subtracting the first result from the second. If there are organic arsenic compounds in water, they are usually converted into methyldiodarsine CH 3 AsI 2 or dimethyliodarsine (CH 3) 2 AsI, which are determined by one or another chromatographic method. Thus, nanogram amounts of a substance can be determined using high performance liquid chromatography.
Many arsenic compounds can be analyzed by the so-called hydride method. It consists in the selective reduction of the analyte to volatile arsine. So, inorganic arsenites are reduced to AsH 3 at pH 5 - 7, and at pH
The neutron activation method is also sensitive. It consists in irradiating the sample with neutrons, while the 75 As nuclei capture neutrons and turn into the 76 As radionuclide, which is detected by characteristic radioactivity with a half-life of 26 hours. In this way, up to 10–10% of arsenic in a sample can be detected, i.e. 1 mg per 1000 tons of substance
The use of arsenic.
About 97% of the mined arsenic is used in the form of its compounds. Pure arsenic is rarely used. Only a few hundred tons of metallic arsenic are produced and used annually throughout the world. In the amount of 3% arsenic improves the quality of bearing alloys. Additives of arsenic to lead significantly increase its hardness, which is used in the production of lead batteries and cables. Small additions of arsenic increase the corrosion resistance and improve the thermal properties of copper and brass. Highly purified arsenic is used in the manufacture of semiconductor devices, in which it is alloyed with silicon or germanium. Arsenic is also used as a dopant, which gives "classical" semiconductors (Si, Ge) a certain type of conductivity.
Arsenic as a valuable additive is also used in non-ferrous metallurgy. Thus, the addition of 0.2 ... 1% As to lead significantly increases its hardness. It has long been noticed that if a little arsenic is added to molten lead, then when casting shot, balls of the correct spherical shape are obtained. The addition of 0.15 ... 0.45% arsenic to copper increases its tensile strength, hardness and corrosion resistance when working in a gassed environment. In addition, arsenic increases the fluidity of copper during casting, facilitates the process of wire drawing. Arsenic is added to some grades of bronzes, brasses, babbits, printing alloys. And at the same time, arsenic very often harms metallurgists. In the production of steel and many non-ferrous metals, they deliberately go to the complication of the process - just to remove all arsenic from the metal. The presence of arsenic in the ore makes production harmful. Harmful twice: first, for people's health; secondly, for a metal, significant impurities of arsenic worsen the properties of almost all metals and alloys.
Various arsenic compounds, which are annually produced in tens of thousands of tons, have a wider application. Oxide As 2 O 3 is used in glassmaking as a glass clarifier. Even the ancient glassmakers knew that white arsenic makes the glass "deaf", i.e. opaque. However, small additions of this substance, on the contrary, lighten the glass. Arsenic is still included in the formulations of some glasses, for example, "Viennese" glass for thermometers.
Arsenic compounds are used as an antiseptic to protect against spoilage and preserve skins, furs and stuffed animals, to impregnate wood, as a component of antifouling paints for the bottoms of ships. In this capacity, salts of arsenic and arsenic acids are used: Na 2 HAsO 4, PbHAsO 4, Ca 3 (AsO 3) 2, etc. The biological activity of arsenic derivatives has interested veterinarians, agronomists, and specialists in the sanitary and epidemiological service. As a result, arsenic-containing livestock growth and productivity stimulants, antihelminthics, drugs for the prevention of diseases of young animals on livestock farms appeared. Arsenic compounds (As 2 O 3 , Ca 3 As 2 , Na 3 As, Parisian greens) are used to control insects, rodents, and also weeds. In the past, such applications were widespread, especially in the cultivation of fruit trees, tobacco and cotton plantations, to rid livestock of lice and fleas, to stimulate growth in poultry and pig production, and to dry cotton before harvesting. Even in ancient China, rice crops were treated with arsenic oxide to protect them from rats and fungal diseases and thus increase the yield. And in South Vietnam, American troops used cacodylic acid (Agent Blue) as a defoliant. Now, due to the toxicity of arsenic compounds, their use in agriculture is limited.
Important areas of application of arsenic compounds are the production of semiconductor materials and microcircuits, fiber optics, the growth of single crystals for lasers, and film electronics. To introduce small, strictly metered amounts of this element into semiconductors, gaseous arsine is used. Gallium arsenides GaAs and indium InAs are used in the manufacture of diodes, transistors, and lasers.
Arsenic also finds limited use in medicine. . Arsenic isotopes 72 As, 74 As, and 76 As with convenient half-lives for research (26 h, 17.8 days, and 26.3 h, respectively) are used to diagnose various diseases.
Ilya Leenson
Arsenic
ARSENIC-a; m.
1. A chemical element (As) is a solid toxic substance of a brilliant gray color, which is part of many minerals. Arsenic oxide. Getting arsenic.
2. A drug containing this substance or its compounds (used as a tonic, antimicrobial, etc. agent). Arsenic treatment. The effect of arsenic on nerve endings.
◁ Arsenic, th, th. M connections. M-th acid. M. preparation. M-th poisoning. Arsenic, th, th. Obsolete Arsenic, th, th. ● The Russian name for this element comes from the word "mouse", because. arsenic was widely used in the destruction of rats and mice.
arsenic(lat. Arsenicum), a chemical element of group V of the periodic system. The Russian name is from "mouse" (arsenic preparations were used to exterminate mice and rats). Forms several modifications. Ordinary arsenic (the so-called metallic, or gray) - fragile crystals with a silvery sheen; density 5.74 g/cm 3 , sublimates at 615°C. It oxidizes and tarnishes in air. Mined from sulfide ores (minerals arsenopyrite, orpiment, realgar). Component of alloys with copper, lead, tin, etc. and semiconductor materials. Arsenic compounds are physiologically active and poisonous; served as one of the first insecticides (see, for example, Metal Arsenates). Inorganic arsenic compounds are used in medicine as general tonic, tonic, organic - as antimicrobial and antiprotozoal (in the treatment of syphilis, amoebiasis, etc.).
ARSENICARSENIC (lat. Arsenicum, from Greek arsen - strong), As (read "arsenicum"), a chemical element with atomic number 33, atomic mass 74.9216. One stable isotope, 75 As, is found in nature. It is located in the VA group in the 4th period of the Periodic Table of the Elements. Electronic configuration of outer layer 4 s 2
p 3
. +3, +5, –3 oxidation states (valencies III, V).
The radius of the atom is 0.148 nm. The radius of the As 3+ ion is 0.191 nm, the As 3+ ion is 0.072 nm (coordination number 4), and the As 5+ ion is 0.047 nm (6). Sequential ionization energies 9.82, 18.62, 28.35, 50.1 and 62.6 eV. Pauling's electronegativity (cm. PAULING Linus) 2.1. Non-metal.
History reference
Arsenic has been known to mankind since ancient times, when orpiment minerals were used as dyes. (cm. AURPIGMENT) As 2 S 3 and realgar (cm. REALGAR) As 4 S 4 (they are mentioned by Aristotle) (cm. ARISTOTLE).
Alchemists, when calcining arsenic sulfides in air, noted that the formation of the so-called white oxide As 2 O 3:
2As 2 S 3 + 9O 2 \u003d 2As2O 3 + 6SO 2
This oxide is a strong poison, it dissolves in water and wine.
For the first time, As was obtained in free form by the German alchemist A. von Boldshtndt in the 13th century by heating arsenic oxide with coal:
As 2 O 3 + 3C \u003d 2As + 3CO
For the image of arsenic, the sign of a writhing snake with an open mouth was used.
Being in nature
Arsenic is a trace element. The content in the earth's crust is 1.7 10 -4% by weight. 160 arsenic-containing minerals are known. Rarely found in its native state. Mineral of industrial importance - arsenopyrite (cm. arsenopyrite) FeAsS. As is often found in lead, copper and silver ores.
Receipt
The enriched ore is subjected to oxidative roasting, then the volatile As 2 O 3 is sublimated. This oxide is reduced with carbon. To purify As, it is subjected to vacuum distillation, then converted to volatile chloride AsCl 3 , which is reduced with hydrogen (cm. HYDROGEN). The resulting arsenic contains 10 -5 -10 -6% impurities by weight.
Physical and chemical properties
Arsenic is a brittle substance gray with a metallic sheen (a-arsenic) with a rhombohedral crystal lattice, a= 0.4135 nm and a = 54.13°. Density 5.74 kg / dm 3.
When heated to 600°C, As sublimates. When the vapor is cooled, a new modification appears - yellow arsenic. Above 270°C, all As forms transform into black arsenic.
As can be melted only in sealed ampoules under pressure. Melting point 817°C at its saturated vapor pressure of 3.6 MPa.
The structure of gray arsenic is similar to the structure of gray antimony and resembles black phosphorus in structure.
Arsenic is reactive. When stored in air, powdered As ignites to form the acidic oxide As 2 O 3 . This oxide exists in vapor in the form of As 4 O 6 dimers.
With careful dehydration of arsenic acid H 3 AsO 4, the highest acidic arsenic oxide As 2 O 5 is obtained, which easily releases oxygen when heated (cm. OXYGEN), turning into As 2 O 3.
The As 2 O 3 oxide corresponds to the orthoarsenic H 3 AsO 3 and metaarsenic weak acids HAsO 2 that exist only in solutions. Their salts are arsenates.
Dilute nitric acid (cm. NITRIC ACID) oxidizes As to H 3 AsO 3 , concentrated nitric acid to H 3 AsO 4 . As does not react with alkalis, it dissolves in water.
When As and H 2 are heated, arsine gas is formed (cm. ARSENIC HYDRIDE) Ash 3 . With fluorine (cm. FLUORINE) and chlorine (cm. CHLORINE) As interacts with self-ignition. When As interacts with sulfur (cm. SULFUR), selenium (cm. SELENIUM) and tellurium (cm. TELLURIUM) chalcogenides are formed: (cm. CHALCOGENIDES) As 2 S 5, As 2 S 3, As 4 S 4, As 2 Se 3, As 2 Te 3, existing in a glassy state. They are semiconductors.
With many metals, As forms arsenides. (cm. ARSENIDES). Gallium arsenide GaAs and indium InAs - semiconductors (cm. SEMICONDUCTORS).
A large number of organic arsenic compounds are known, in which there is a chemical bond As - C: organoarsines R n AsH 3-n (n= 1.3), tetraorganodiarsines R 2 As - AsR 2 and others.
Application
As of high purity is used for the synthesis of semiconductor materials. Sometimes As is added to steels as an alloying addition.
In 1909 the German microbiologist P. Ehrlich (cm. ERLICH Paul) received "drug 606", an effective cure for malaria, syphilis, and relapsing fever.
Physiological action
Arsenic and all its compounds are poisonous. In acute arsenic poisoning, vomiting, abdominal pain, diarrhea, depression of the central nervous system are observed. Help and antidotes for arsenic poisoning: taking aqueous solutions of Na 2 S 2 O 3. Gastric lavage, intake of milk and cottage cheese; specific antidote - unithiol. MPC in the air for arsenic 0.5 mg / m 3. Work with arsenic in sealed boxes, using protective clothing. Due to the high toxicity of arsenic compounds, they were used by Germany as poisonous substances in the First World War.
In areas where there is an excess of arsenic in soil and water, it accumulates in the thyroid gland of people and causes endemic goiter.
encyclopedic Dictionary. 2009 .
Synonyms:See what "arsenic" is in other dictionaries:
ARSENIC- (Arsenum, Arsenium, Arseni cum), solid metalloid, symbol. As; at. in. 74.96. In the periodic system of elements, it occupies the 33rd place in order, in the 5th row of the V group. Natural compounds of M. with sulfur (realgar and orpiment) were known as early as ... ... Big Medical Encyclopedia
ARSENIC- see ARSENIC (As). Since arsenic and its compounds are widely used in the national economy, it is found in wastewater from various industries - metallurgical, chemical-pharmaceutical, textile, glass, leather, chemical ... Fish Diseases: A Handbook
Arsenic- (crude arsenic) is a solid extracted from natural arsenopyrites. It exists in two main forms: a) ordinary, the so-called metallic arsenic, in the form of shiny steel-colored crystals, fragile, not ... Official terminology
- (symbol As), a poisonous semi-metallic element of the fifth group of the periodic table; was probably obtained in 1250. Compounds containing arsenic are used as a poison for rodents, insects and as a weed killer. They also apply... Scientific and technical encyclopedic dictionary
- (Arsenium), As, a chemical element of group V of the periodic system, atomic number 33, atomic mass 74.9216; gray, yellow or black non-metal, mp 817 shC, sublimates at 615 shC. Arsenic is used to obtain semiconductor ... ... Modern Encyclopedia
Arsenic- (Arsenium), As, a chemical element of group V of the periodic system, atomic number 33, atomic mass 74.9216; gray, yellow or black non-metal, mp 817 °C, sublimes at 615 °C. Arsenic is used to obtain semiconductor ... ... Illustrated Encyclopedic Dictionary
ARSENIC- chem. element, symbol As (lat. Arsenicum), at. n. 33, at. m. 74.92; non-metal, exists in several allotropic modifications, density 5720 kg/m3. Under normal conditions, the most chemically resistant is the so-called metallic, or gray, arsenic. Great Polytechnic Encyclopedia
Finding arsenic in nature
Arsenic is a trace element. Content in the earth's crust 1.7 10-4% by weight. This substance can occur in its native state, has the form of metallic lustrous gray shells or dense masses consisting of small grains. About 200 arsenic-containing minerals are known. In small concentrations, it is often found in lead, copper and silver ores. Quite often there are two natural compounds of arsenic with sulfur: orange-red transparent realgar AsS and lemon-yellow orpiment As2S3. A mineral of industrial importance - arsenopyrite (arsenic pyrite) FeAsS or FeS2 FeAs2, arsenic pyrite - löllingite (FeAs2) is also mined.Getting arsenic
There are many ways to obtain arsenic: sublimation of natural arsenic, thermal decomposition of arsenic pyrites, reduction of arsenic anhydride, etc. Currently, to obtain metallic arsenic, arsenopyrite is most often heated in muffle furnaces without air access. This releases arsenic, the vapors of which condense and turn into solid arsenic in iron pipes coming from furnaces and in special ceramic receivers. The residue in the furnaces is then heated with air access, and then the arsenic is converted to As2O3. Metallic arsenic is obtained in rather small quantities, and the main part of arsenic-containing ores is processed into white arsenic, that is, into arsenic trioxide - arsenic anhydride As2O3.Application of arsenic
- The use of arsenic in metallurgy is used for alloying lead alloys used for the preparation of shot, since when shot is cast by a tower method, drops of an arsenic-lead alloy acquire a strictly spherical shape, and in addition, the strength and hardness of lead increase.
- Application in electrical engineering - High purity arsenic (99.9999%) is used for the synthesis of a number of practically very valuable and important semiconductor materials - arsenides and complex diamond-like semiconductors.
- Application as a dye - arsenic sulfide compounds - orpiment and realgar - are used in painting as paints.
- Application in the leather industry - used as a means to remove hair from the skin.
- Application in pyrotechnics - realgar is used to obtain the "Greek" or "Indian" fire that occurs when burning a mixture of realgar with sulfur and nitrate (bright white flame).
- Use in medicine - many of the arsenic compounds in very small doses are used as drugs to combat anemia and a number of serious diseases, as they have a clinically significant stimulating effect on a number of body functions, in particular, on hematopoiesis. Of the inorganic compounds of arsenic, arsenic anhydride can be used in medicine for the preparation of pills and in dental practice in the form of a paste as a necrotizing drug (the same “arsenic” that is placed in the tooth canal before removing the nerve and filling). Currently, arsenic preparations are rarely used in dental practice due to toxicity and the possibility of painless tooth denervation under local anesthesia.
- Application in glass production - arsenic trioxide makes glass "deaf", i.e. opaque. However, small additions of this substance, on the contrary, lighten the glass. Arsenic is still included in the formulations of some glasses, for example, "Viennese" glass for thermometers and semi-crystal.
The most promising field of application of arsenic is undoubtedly semiconductor technology. Gallium arsenides GaAs and indium arsenides InAs acquired particular importance in it. Gallium arsenide is also needed for an important area of electronic technology - optoelectronics, which arose in 1963 ... 1965. at the intersection of solid state physics, optics and electronics. The same material helped create the first semiconductor lasers.
Why did arsenides turn out to be promising for semiconductor technology? To answer this question, let us briefly recall some of the basic concepts of semiconductor physics: "valence band", "forbidden band" and "conduction band".
Unlike a free electron, which can have any energy, an electron enclosed in an atom can only have certain, well-defined values of energy. From the possible values of the energy of electrons in an atom, energy bands are added. By virtue of the well-known Pauli principle, the number of electrons in each zone cannot exceed a certain certain maximum. If the band is empty, then, of course, it cannot participate in the creation of conductivity. The electrons of the completely filled band do not participate in the conduction either: since there are no free levels, an external electric field cannot cause a redistribution of electrons and thereby create an electric current. Conductivity is possible only in a partially filled zone. Therefore, bodies with a partially filled band are referred to as metals, and bodies in which the energy spectrum of electronic states consists of filled and empty bands are referred to as dielectrics or semiconductors.
We also recall that completely filled bands in crystals are called valence bands, partially filled and empty bands are called conduction bands, and the energy interval (or barrier) between them is called the band gap.
The main difference between dielectrics and semiconductors lies precisely in the band gap: if an energy of more than 3 eV is needed to overcome it, then the crystal is referred to as dielectrics, and if less, to semiconductors.
Compared to classical group IV semiconductors, germanium and silicon, group III element arsenides have two advantages. The band gap and the mobility of charge carriers in them can be varied over a wider range. And the more mobile the charge carriers, the higher frequencies the semiconductor device can operate. The band gap is chosen depending on the purpose of the device.
So, for rectifiers and amplifiers designed to operate at elevated temperatures, a material with a large bandgap is used, and for cooled infrared radiation receivers, a material with a small bandgap is used.
Gallium arsenide has gained particular popularity because it has good electrical characteristics, which it retains in a wide temperature range - from minus to plus 500 ° C. For comparison, we point out that indium arsenide, which is not inferior to GaAs in electrical properties, begins to lose them already at room temperature, germanium - at 70...80, and silicon - at 150...200°C.
Arsenic is also used as a dopant, which gives "classical" semiconductors (Si, Ge) a certain type of conductivity. In this case, a so-called transition layer is created in the semiconductor, and, depending on the purpose of the crystal, it is doped in such a way as to obtain a transition layer at different depths. In crystals intended for the manufacture of diodes, it is “hidden” deeper; if solar batteries are made from semiconductor crystals, then the depth of the transition layer is no more than one micrometer.
Arsenic as a valuable additive is also used in non-ferrous metallurgy. Thus, the addition of 0.2 ... 1% As to lead significantly increases its hardness. Shot, for example, is always made from lead alloyed with arsenic - otherwise you will not get a strictly spherical shape of shots.
The addition of 0.15 ... 0.45% arsenic to copper increases its tensile strength, hardness and corrosion resistance when working in a gassed environment. In addition, arsenic increases the fluidity of copper during casting, facilitates the process of wire drawing.
Arsenic is added to some grades of bronzes, brasses, babbits, printing alloys.
And at the same time, arsenic very often harms metallurgists. In the production of steel and many non-ferrous metals, they deliberately go to the complication of the process - just to remove all arsenic from the metal. The presence of arsenic in the ore makes production harmful. Harmful twice: first, for people's health; secondly, for a metal, significant impurities of arsenic worsen the properties of almost all metals and alloys.
All conn. arsenic, p-rimye in water and slightly acidic environments (eg, gastric juice), are extremely toxic; MPC in the air of arsenic and its Comm. (except AsH3) in terms of arsenic 0.5 mg/m3. Comm. As (III) are more poisonous than Comm. As(V). From inorg. conn. As2O3 and AsH3 are especially dangerous. When working with arsenic and its Comm. necessary: complete sealing of equipment, removal of dust and gases by intensive ventilation, personal hygiene (anti-dust clothing, glasses, gloves, gas mask), frequent medical monitoring; women and teenagers are not allowed to work. In acute arsenic poisoning, vomiting, abdominal pain, diarrhea, depression of the center are observed. nervous system. Help and antidotes for arsenic poisoning: taking aqueous solutions of Na2S2O3, gastric lavage, taking milk and cottage cheese; specific antidote - unithiol. A particular problem is the removal of arsenic from exhaust gases, technol. waters and by-products of processing ores and concentrates of non-ferrous and rare metals and iron. Naib. A promising way to bury arsenic is by converting it into practically insoluble sulfide glasses.
Arsenic has been known since ancient times. Even Aristotle mentioned his nature. sulfur compounds. It is not known who first obtained elemental arsenic, the achievement is usually attributed to Albertus Magnus c. 1250. Chem. Arsenic was recognized as an element by A. Lavoisier in 1789.
This is element #33, which has a well-deserved ill repute, and yet is very useful in many cases.
The content of arsenic in the earth's crust is only 0.0005%, but this element is quite active, and therefore there are more than 120 minerals containing arsenic. The main industrial mineral of arsenic is arsenopyrite FeAsS. There are large copper-arsenic deposits in the USA, Sweden, Norway and Japan, arsenic-cobalt deposits in Canada, arsenic-tin deposits in Bolivia and England. In addition, gold-yshyakovye deposits are known in the USA and France. Russia has numerous deposits of arsenic in Yakutia and the Caucasus, Central Asia and the Urals, Siberia and Chukotka, Kazakhstan and Transbaikalia. Arsenic is one of the few elements for which the demand is less than the ability to produce them. World production of arsenic (excluding socialist countries) in terms of As2O3 approx. 50 thousand tons (1983); ~11 tons of elemental arsenic of high purity are obtained from them for the synthesis of semiconductor compounds.
The X-ray fluorescent method for the analysis of arsenic is quite simple and safe, unlike the chemical method. Pure pulp is pressed into tablets and used as a reference. GOST 1293.4-83, GOST 1367.1-83, GOST 1429.10-77, GOST 2082.5-81, GOST 2604.11-85, GOST 6689.13-92, GOST 11739.14-99 The determination is made using an X-ray fluorescence spectrometer. The most proven in this area are the edx 3600 B and edx 600 spectrometers.
Arsenic - the classic poison of medieval and modern poisoners
and medicine in modern sports and rehabilitation medicine
Toxic and poisonous stones and minerals
Arsenic(lat. Arsenicum), As, a chemical element of group V of the periodic system of Mendeleev, atomic number 33, atomic mass 74.9216; steel gray crystals. The element consists of one stable isotope, 75 As. Poisonous in any form, medicine.
History reference.
Natural compounds of arsenic with sulfur (orpiment As 2 S 3 , realgar As 4 S 4) were known to the peoples of the ancient world, who used these minerals as medicines and paints. The product of burning arsenic sulfides, arsenic oxide (III) As 2 O 3 ("white arsenic"), was also known.
The name arsenikon is found already at the beginning of our era; it is derived from the Greek arsen - strong, courageous and served to designate arsenic compounds (according to their effect on the body). The Russian name is believed to have come from "mouse" ("death" - according to the use of arsenic preparations for killing yaks, as well as the extermination of mice and rats). The chemical preparation of free arsenic is attributed to 1250 AD. In 1789, A. Lavoisier included arsenic in the list of chemical elements.
Arsenic. Belorechenskoe deposit, Sev. Caucasus, Russia. ~10x7 cm. Photo: A.A. Evseev.
Distribution of arsenic in nature.
The average content of arsenic in the earth's crust (clarke) is 1.7 * 10 -4% (by mass), in such quantities it is present in most igneous rocks. Since arsenic compounds are volatile at high temperatures (dry volcanic sublimation on batholiths), the element is sublimated into the atmosphere and air in the form of metal vapors (mirages - the air below ripples) does not accumulate during sublimation through cracks and tubes magmatic lava processes; it is concentrated, precipitating from vapors and hot deep waters on crystal formation catalysts - metallic iron (together with S, Se, Sb, Fe, Co, Ni, Cu and other elements).
During volcanic eruptions (during the dry sublimation of arsenic), arsenic in the form of its volatile compounds enters the atmosphere. Since arsenic is polyvalent, its migration is affected by the redox environment. Under the oxidizing conditions of the earth's surface, arsenates (As 5+) and arsenites (As 3+) are formed.
These are rare minerals found in areas of arsenic deposits. Native arsenic and As 2+ minerals are even rarer. Of the minerals and arsenic compounds (about 180), arsenopyrite FeAsS is of industrial importance (the iron atom is the center of pyrite formation, the formula of the starting "single crystal" is Fe + (As + S)).
Arsenopyrite vein. Trifonovskaya shkh., Kochkarskoye deposit (Au), Plast, Yu. Ural, Russia. Arsenic. Photo: A.A. Evseev.
Small amounts of arsenic are essential for life. However, in the areas of arsenic deposits and the activity of young volcanoes, soils in places contain up to 1% arsenic, which is associated with livestock diseases and the death of vegetation. The accumulation of arsenic is especially characteristic of the landscapes of steppes and deserts, in the soils of which arsenic is inactive. In humid climates and when watering plants and soils, arsenic is washed out of the soil.
In living matter, on average, 3·10 -5% arsenic, in rivers 3·10 -7%. Arsenic, brought by rivers into the ocean, settles relatively quickly. In sea water, 1 * 10 -7% arsenic (there is a lot of gold that displaces it), but in clays and arsenic shales (along the banks of rivers and reservoirs, in clayey black formations and along the edges of quarries) - 6.6 * 10 - 4 %. Sedimentary iron ores, ferromanganese and other iron nodules are often enriched in arsenic.
Physical properties of arsenic.
Arsenic has several allotropic modifications. Under normal conditions, the most stable is the so-called metallic, or gray, arsenic (α-As) - gray steel fragile crystalline mass (according to properties - like pyrite, gold blende, iron pyrite); on a fresh fracture it has a metallic luster, it quickly tarnishes in air, as it is covered with a thin film of As 2 O 3 .
Arsenic is rarely referred to as silver blende - the case of the Clerks of Tsar A.M. Romanov in the middle of the 17th century, "silver", not malleable, sometimes in powder, can be ground - poison for the Tsar of All Rus'. The most famous Spanish scandal in the tavern of poisoners near the mill "Don Quixote" on the way to Almaden, Spain, where red cinnabar is mined on the European continent (scandals about the sale of virgins in the Krasnodar Territory of the Russian Federation, the village of Novy, crystal red cinnabar, do not want to work) .
Arsenopyrite. Druse of prismatic crystals with calcite spherulites. Freiberg, Saxony, Germany. Photo: A.A. Evseev.
The crystal lattice of gray arsenic is rhombohedral (a \u003d 4.123Å, angle α \u003d 54 o 10 ", x \u003d 0.226), layered. Density 5.72 g / cm 3 (at 20 o C), electrical resistivity 35 * 10 -8 ohm * m, or 35 * 10 -6 ohm * cm, temperature coefficient of electrical resistance 3.9 10 -3 (0 o -100 o C), Brinell hardness 1470 MN / m 2, or 147 kgf / mm 2 (3- 4 according to Moocy); arsenic is diamagnetic.
Under atmospheric pressure, arsenic sublimates at 615 o C without melting, since the triple point of α-As lies at 816 o C and a pressure of 36 at.
Arsenic vapor consists up to 800 o C of As 4 molecules, above 1700 o C - only of As 2. When arsenic vapor condenses on a surface cooled by liquid air, yellow arsenic is formed - transparent, wax-soft crystals, with a density of 1.97 g / cm 3, similar in properties to white phosphorus.
Under the action of light or with slight heating, it turns into gray arsenic. Vitreous-amorphous modifications are known: black arsenic and brown arsenic, which, when heated above 270 o C, turn into gray arsenic
Chemical properties of arsenic.
The configuration of the outer electrons of the arsenic atom is 3d 10 4s 2 4p 3 . In compounds, arsenic has oxidation states +5, +3 and -3. Gray arsenic is less chemically active than phosphorus. When heated in air above 400 o C, arsenic burns, forming As 2 O 3 .
Arsenic combines directly with halogens; under normal conditions, AsF 5 - gas; AsF 3 , AsCl 3 , AsBr 3 - colorless volatile liquids; AsI 3 and As 2 I 4 are red crystals. When arsenic is heated with sulfur, sulfides are obtained: orange-red As 4 S 4 and lemon-yellow As 2 S 3 .
Pale yellow silver sulfide As 2 S 5 ( arsenopyrite) is deposited by passing H 2 S into an ice-cooled solution of arsenic acid (or its salts) in fuming hydrochloric acid: 2H 3 AsO 4 + 5H 2 S \u003d As 2 S 5 + 8H 2 O; around 500 o C it decomposes into As 2 S 3 and sulfur.
All arsenic sulfides are insoluble in water and dilute acids. Strong oxidizers (mixtures of HNO 3 + HCl, HCl + KClO 3) convert them into a mixture of H 3 AsO 4 and H 2 SO 4 .
Sulfide As 2 S 3 easily dissolves in sulfides and polysulfides of ammonium and alkali metals, forming salts of acids - thioarsenic H 3 AsS 3 and thiomarsenic H 3 AsS 4 .
With oxygen, arsenic gives oxides: arsenic oxide (III) As 2 O 3 - arsenic anhydride and arsenic oxide (V) As 2 O 5 - arsenic anhydride. The first of them is formed by the action of oxygen on arsenic or its sulfides, for example 2As 2 S 3 + 9O 2 = 2As 2 O 3 + 6SO 2.
As 2 O 3 vapors condense into a colorless vitreous mass, which becomes opaque over time due to the formation of small cubic crystals, density 3.865 g/cm 3 . The vapor density corresponds to the formula As 4 O 6 ; above 1800 o C vapor consists of As 2 O 3 .
In 100 g of water, 2.1 g of As 2 O 3 is dissolved (at 25 o C). Arsenic (III) oxide is an amphoteric compound, with a predominance of acidic properties. Salts (arsenites) are known that correspond to orthoarsenic H 3 AsO 3 and metaarsenic HAsO 2 acids; the acids themselves have not been obtained. Only alkali metal and ammonium arsenites are soluble in water.
As 2 O 3 and arsenites are usually reducing agents (for example, As 2 O 3 + 2I 2 + 5H 2 O \u003d 4HI + 2H 3 AsO 4), but they can also be oxidizing agents (for example, As 2 O 3 + 3C \u003d 2As + ZSO ).
Arsenic (V) oxide is obtained by heating arsenic acid H 3 AsO 4 (about 200 o C). It is colorless, about 500 o C decomposes into As 2 O 3 and O 2 . Arsenic acid is obtained by the action of concentrated HNO 3 on As or As 2 O 3 .
Salts of arsenic acid (arsenates) are insoluble in water, with the exception of alkali metal and ammonium salts. Salts corresponding to acids orthoarsenic H 3 AsO 4 , metaarsenic HAsO 3 and pyromensic H 4 As 2 O 7 are known; the last two acids have not been obtained in the free state. When fused with metals, arsenic mostly forms compounds (arsenides).
Getting arsenic.
Arsenic is obtained in industry by heating arsenic pyrite:
FeAsS = FeS + As
or (more rarely) reduction of As 2 O 3 with coal. Both processes are carried out in refractory clay retorts connected to a receiver for arsenic vapor condensation.
Arsenic anhydride is produced by the oxidative roasting of arsenic ores or as a by-product of the roasting of polymetallic ores, which almost always contain arsenic. During oxidative roasting, As 2 O 3 vapors are formed, which condense in the trapping chambers.
Raw As 2 O 3 is purified by sublimation at 500-600 o C. Purified As 2 O 3 is used for the production of arsenic and its preparations.
The use of arsenic.
Small additions of arsenic (0.2-1.0% by weight) are introduced into lead used for the production of shotgun shot (arsenic increases the surface tension of molten lead, due to which the shot takes on a shape close to spherical; arsenic slightly increases the hardness of lead). As a partial substitute for antimony, arsenic is found in some babbits and printing alloys.
Pure arsenic is not poisonous, but all of its compounds, which are soluble in water or can go into solution under the action of gastric juice, are extremely poisonous; arsenic hydrogen is especially dangerous. Of the arsenic compounds used in production, arsenic anhydride is the most toxic.
Almost all sulfide ores of non-ferrous metals, as well as iron (sulfur) pyrite, contain an admixture of arsenic. Therefore, during their oxidative roasting, along with sulfur dioxide SO 2, As 2 O 3 is always formed; most of it condenses in the smoke channels, but in the absence or low efficiency of treatment facilities, the exhaust gases of ore kilns entrain significant amounts of As 2 O 3 .
Pure arsenic, although not toxic, is always coated with poisonous As 2 O 3 when stored in air. In the absence of properly performed ventilation, it is extremely dangerous to pickle metals (iron, zinc) with technical sulfuric or hydrochloric acids containing an admixture of arsenic, since arsenic hydrogen is formed in this case.
Arsenic in the body.
As a trace element, arsenic is ubiquitous in wildlife. The average content of arsenic in soils is 4 * 10 -4%, in plant ash - 3 * 10 -5%. The content of arsenic in marine organisms is higher than in terrestrial organisms (in fish, 0.6-4.7 mg per 1 kg of raw matter accumulates in the liver).
The largest amount of it (per 1 g of tissue) is found in the kidneys and liver (when ingested, it does not accumulate in the brain). A lot of arsenic is found in the lungs and spleen, skin and hair; relatively little - in the cerebrospinal fluid, brain (mainly in the pituitary gland), sex glands and others.
In tissues, arsenic is in the main protein fraction("stone of bodybuilders and athletes"), much less - in acid-soluble and only a small part of it is found in the lipid fraction. They are treated with progressive muscular dystrophy - it does not accumulate in the brain and bones (sport doping, they treat hostages and prisoners of concentration camps like "Ausvents" in Poland, the EU, 1941-1944).
Arsenic is involved in redox reactions: oxidative breakdown of complex biological carbohydrates and sugars, fermentation, glycolysis, etc. Improves mental abilities (contributes to the process of breaking down sugars in the brain). Arsenic compounds are used in biochemistry as specific enzyme inhibitors for studying metabolic reactions. Promotes the disintegration of biological tissues (accelerates). It is actively used in dentistry and oncology - to eliminate rapidly growing and early aging cancer cells and tumors.
Mixture (hard sulfide alloy) of thallium, arsenic and lead: Hutchinsonite (Hutchinsonite)
Mineral formula (Pb, Tl)S` Ag2S * 5 As2 S5 is a complex sulfide and adsenide carbide salt. Rhombus. Crystals prismatic to acicular. Cleavage perfect according to (010). The aggregates are radially acicular, granular. Hardness 1.5-2. Specific gravity 4.6. Red. Diamond glitter. In hydrothermal deposits with dolomite, with sulfides and arsenides of Zn, Fe, As and sulfoarsenides. The result of dry sulfuric and arsenic sublimation of magma through calderas and open vents of volcanoes, as well as dry sublimation through cracks in deep-seated igneous plutonites from the Earth's red-hot magma. Contains silver. It is one of the ten very dangerous for human and animal health and carcinogenic stones and minerals that crystallize under modern conditions among other rocks in the form of harmful, dangerous to health (with unauthorized handling) and deceptive ore beauty. In the photo - Hutchinsonite with orpiment.
Poisonous minerals. Hutchinsonite - named after the mineralogist Hutchinson from the University of Cambridge and looks like lead (it can be used to protect against radiation). Opened in 1861. A deadly mixture (hard alloy) of thallium, arsenic and lead. Contact with this mineral can lead to hair loss (alopecia, baldness, baldness), complex skin diseases and death. All of its main components are poisonous. Very similar to lead, native silver, pyrite ("dry pyrite") and arsenopyrite. It also looks like antimonite (antimony compound, also very poisonous). It also looks like zeolites. Gutchinsonite is a dangerous and amazing hardmetal mixture of thallium, lead and arsenic. Three rare, very expensive and valuable ore metals form a poisonous, deadly cocktail of minerals that must be handled with the utmost care. They affect the brain, heart and liver at the same time.
Thallium is the gloomy twin of lead. This dense, fatty metal is similar in atomic weight to lead, but even more lethal. Thallium is a rare metal that appears in highly toxic compounds made up of strange combinations of elements (hard alloys). The effects of thallium exposure are more dangerous than lead, and include hair loss (alopecia, alopecia), serious illness through skin contact, and in many cases death. Hutchinsonite was named after John Hutchinson, a renowned mineralogist at the University of Cambridge. This mineral can be found in the mountainous regions of Europe, most often in ore deposits. A mineral popular in medical dentistry, etc. Alcoholics are afraid of the mineral.
Hutchinsonite (Hatchinsonite) is sometimes jokingly called "dry" or "hard alcohol", "hard alcohol" (and not only for the harmful effects of intoxicating poisoning on the body and human health). The chemical formula of food alcohol (alcohol) is C2 H5 (OH). Hutchinsonite (Hatchinsonite) has a chemical formula - 5 As2 S5 * (Pb, Tl) S` Ag2 S or 5 As2 S5 * (Pb, Tl) S` Ag Ag S. The formula of Hutchinsonite (Hatchinsonite) is sometimes rewritten differently - As2 S5 * ( Pb) + As2 S5 * (Tl) + As2 S5 * S + As2 S5 * Ag + As2 S5 * AgS. The chemical separation of components in production is also carried out according to the type of different alcohols (layers of mechanical enrichment, different in mass and weight, which are crushed by ultrasound and separated in a centrifuge or on a vibrating platform - horror film "Aliens"). Other similar variants of the chemical formula are possible (composition varies).
ADR 6.1
Toxic substances (poison)
Risk of poisoning by inhalation, skin contact or if swallowed. Hazardous to the aquatic environment or the sewerage system
Use an emergency exit mask
ADR 3
Flammable liquids
Fire risk. Risk of explosion. Containers may explode when heated (super hazardous - easy to burn)
ADR 2.1
flammable gases
Fire risk. Risk of explosion. May be under pressure. Choking risk. May cause burns and/or frostbite. Capacities can explode when heated (super-dangerous - practically do not burn)
Use cover. Avoid low surface areas (holes, lowlands, trenches)
Red diamond, ADR number, black or white flame
ADR 2.2
gas bottle Non-flammable, non-toxic gases.
Choking risk. May be under pressure. May cause frostbite (similar to a burn - pallor, blisters, black gas gangrene - creaking). Containers can explode when heated (super-dangerous - an explosion from a spark, flame, match, practically does not burn)
Use cover. Avoid low surface areas (holes, lowlands, trenches)
Green rhombus, ADR number, black or white gas cylinder (such as "cylinder", "thermos")
ADR 2.3
Toxic gases. Skull and crossbones
Danger of poisoning. May be under pressure. May cause burns and/or frostbite. Containers can explode when heated (super-dangerous - instant spread of gases around the area)
Use an emergency exit mask. Use cover. Avoid low surface areas (holes, lowlands, trenches)
White diamond, ADR number, black skull and crossbones
| Name of especially dangerous cargo during transportation | Number UN | Class ADR |
| Arsenic (III) oxide ARSENE TRIOXIDE | 1561 | 6.1 |
| 1685 | 6.1 | |
| 1557 | 6.1 | |
| 1561 | 6.1 | |
| Calcium arsenic acid ARSENATE COMPOUND SOLID, N.Z.K. inorganic including: Arsenati, n.c.c., Arsenite, n.c.c., Arsene sulfides, n.c.c. | 1557 | 6.1 |
| Calcium arsenic acid CALCIUM ARSENATE | 1573 | 6.1 |
| CALCIUM ARSENATE | 1573 | 6.1 |
| CALCIUM ARSENATE AND CALCIUM ARSENITE MIXTURE SOLID | 1574 | 6.1 |
| calcium arsenite | 1557 | 6.1 |
| AMMONIUM ARSENATE | 1546 | 6.1 |
| Arsenic anhydride ARSENE TRIOXIDE | 1561 | 6.1 |
| ARSEN | 1558 | 6.1 |
| ARSENIC DUST | 1562 | 6.1 |
| Arsene hydrogen Arsine | 2188 | 2 |
| Arsene-soda solution | 1556 | 6.1 |
| ARSENE BROMIDE | 1555 | 6.1 |
| ARSENE PENTAOXIDE | 1559 | 6.1 |
| ARSENE COMPOUND, LIQUID, N.C.C. inorganic, including: Arsenati, n.c.c., Arsenite, n.c.c., but Arsene sulfides, n.c.c. | 1556 | 6.1 |
| ARSENE COMPOUND, SOLID, N.C.K. inorganic, including: Arsenati, n.c.c., Arsenite, n.c.c., but Arsene sulfides, n.c.c. | 1557 | 6.1 |
| Arsene trioxide | 1561 | 6.1 |
| ARSENE TRICHLORIDE | 1560 | 6.1 |
| ARSINE | 2188 | 2 |
| IRON(II) ARSENATE | 1608 | 6.1 |
| IRON(III) ARSENATE | 1606 | 6.1 |
| IRON(III) ARSENITE | 1607 | 6.1 |
| POTASSIUM ARSENATE | 1677 | 6.1 |
| POTASSIUM ARSENITE | 1678 | 6.1 |
| ARSENIC ACID, SOLID | 1554 | 6.1 |
| ARSENIC ACID, LIQUID | 1553 | 6.1 |
| MAGNESIUM ARSENATE | 1622 | 6.1 |
| COPPER ARSENITE | 1586 | 6.1 |
| COPPER ACETOARSENITE | 1585 | 6.1 |
| Sodium Arsenite SODIUM ARSENITE SOLID | 2027 | 6.1 |
| Sodium arsenate SODIUM ARSENATE | 1685 | 6.1 |
| SODIUM AZIDE | 1687 | 6.1 |
| SODIUM ARSENATE | 1685 | 6.1 |
| SODIUM ARSENITE, SOLID | 2027 | 6.1 |
| SODIUM ARSENITE AQUEOUS SOLUTION | 1686 | 6.1 |
| Tin arsenide | 1557 | 6.1 |
| Tin arsenic Tin arsenite | 1557 | 6.1 |
| 2760 | 3 | |
| ARSE-CONTAINING PESTICIDE, LIQUID, FLAMMABLE, TOXIC, flash point less than 23 o С | 2760 | 3 |
| ARSE-CONTAINING PESTICIDE, SOLID, TOXIC | 2759 | 6.1 |
| PESTICIDE, ARSE-CONTAINING, LIQUID, TOXIC | 2994 | 6.1 |
| ARSE-CONTAINING PESTICIDE, LIQUID, TOXIC, FLAMMABLE, flash point not less than 23 o С | 2993 | 6.1 |
| MERCURY (II) ARSENATE | 1623 | 6.1 |
| LEAD ARSENATI | 1617 | 6.1 |
| LEAD ARSENITE | 1618 | 6.1 |
| ARSENO-ORGANIC COMPOUND, LIQUID, N.C.C. | 3280 | 6.1 |
| ARSENO-ORGANIC SOLID COMPOUND, N.C.C.* | 3465 | 6.1 |
| SILVER ARSENITE | 1683 | 6.1 |
| STRONTIUM ARSENITE | 1691 | 6.1 |
| ZINC ARSENATE, ZINC ARSENITE or ZINC ARSENATE AND ZINC ARSENITE MIXTURE | 1712 | 6.1 |
