Age of iron Unlike silver, gold, copper and other metals, iron is rarely found in nature in its pure form, so it was mastered by man relatively late. The first samples of iron that our ancestors held in their hands were unearthly, meteoric

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Chemical formula

Molar Mass of FeS, Iron(II) Sulfide 87.91 g/mol

Mass fractions of elements in the compound

Using the Molar Mass Calculator

• Chemical formulas must be entered case sensitive
• Indexes are entered as regular numbers
• The dot on the midline (multiplication sign), used, for example, in the formulas of crystalline hydrates, is replaced by a regular dot.
• Example: instead of CuSO₄ 5H₂O, the converter uses the spelling CuSO4.5H2O for ease of entry.

Molar mass calculator

mole

All substances are made up of atoms and molecules. In chemistry, it is important to accurately measure the mass of substances entering into a reaction and resulting from it. By definition, the mole is the SI unit for the amount of a substance. One mole contains exactly 6.02214076×10²³ elementary particles. This value is numerically equal to the Avogadro constant N A when expressed in units of moles⁻¹ and is called Avogadro's number. Amount of substance (symbol n) of a system is a measure of the number of structural elements. A structural element can be an atom, a molecule, an ion, an electron, or any particle or group of particles.

Avogadro's constant N A = 6.02214076×10²³ mol⁻¹. Avogadro's number is 6.02214076×10²³.

In other words, a mole is the amount of a substance equal in mass to the sum of the atomic masses of the atoms and molecules of the substance, multiplied by the Avogadro number. The mole is one of the seven basic units of the SI system and is denoted by the mole. Since the name of the unit and its symbol are the same, it should be noted that the symbol is not declined, unlike the name of the unit, which can be declined according to the usual rules of the Russian language. One mole of pure carbon-12 equals exactly 12 grams.

Molar mass

Molar mass is a physical property of a substance, defined as the ratio of the mass of that substance to the amount of the substance in moles. In other words, it is the mass of one mole of a substance. In the SI system, the unit of molar mass is kilogram/mol (kg/mol). However, chemists are accustomed to using the more convenient unit g/mol.

molar mass = g/mol

Molar mass of elements and compounds

Compounds are substances made up of different atoms that are chemically bonded to each other. For example, the following substances, which can be found in the kitchen of any housewife, are chemical compounds:

• salt (sodium chloride) NaCl
• sugar (sucrose) C₁₂H₂₂O₁₁
• vinegar (acetic acid solution) CH₃COOH

The molar mass of chemical elements in grams per mole is numerically the same as the mass of the element's atoms expressed in atomic mass units (or daltons). The molar mass of compounds is equal to the sum of the molar masses of the elements that make up the compound, taking into account the number of atoms in the compound. For example, the molar mass of water (H₂O) is approximately 1 × 2 + 16 = 18 g/mol.

Molecular mass

Molecular weight (the old name is molecular weight) is the mass of a molecule, calculated as the sum of the masses of each atom that makes up the molecule, multiplied by the number of atoms in this molecule. The molecular weight is dimensionless a physical quantity numerically equal to the molar mass. That is, the molecular weight differs from the molar mass in dimension. Although the molecular mass is a dimensionless quantity, it still has a value called the atomic mass unit (amu) or dalton (Da), and is approximately equal to the mass of one proton or neutron. The atomic mass unit is also numerically equal to 1 g/mol.

Molar mass calculation

The molar mass is calculated as follows:

• determine the atomic masses of the elements according to the periodic table;
• determine the number of atoms of each element in the compound formula;
• determine the molar mass by adding the atomic masses of the elements included in the compound, multiplied by their number.

For example, let's calculate the molar mass of acetic acid

It consists of:

• two carbon atoms
• four hydrogen atoms
• two oxygen atoms

• carbon C = 2 × 12.0107 g/mol = 24.0214 g/mol
• hydrogen H = 4 × 1.00794 g/mol = 4.03176 g/mol
• oxygen O = 2 × 15.9994 g/mol = 31.9988 g/mol
• molar mass = 24.0214 + 4.03176 + 31.9988 = 60.05196 g/mol

Our calculator does just that. You can enter the formula of acetic acid into it and check what happens.

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Abstract on the topic:

Iron sulfides ( FeS , FeS 2 ) and calcium ( CaS )

Made by Ivanov I.I.

Introduction

Properties

Origin (genesis)

Sulfides in nature

Properties

Origin (genesis)

Spreading

Application

Pyrrhotite

Properties

Origin (genesis)

Application

Marcasite

Properties

Origin (genesis)

Place of Birth

Application

Oldgamite

Receipt

Physical properties

Chemical properties

Application

chemical weathering

Thermal analysis

thermogravimetry

Derivatography

Derivatographic analysis of pyrite

Sulfides

Sulfides are natural sulfur compounds of metals and some non-metals. Chemically, they are considered as salts of hydrosulfide acid H 2 S. A number of elements form polysulfides with sulfur, which are salts of polysulfuric acid H 2 S x. The main elements that form sulfides are Fe, Zn, Cu, Mo, Ag, Hg, Pb, Bi, Ni, Co, Mn, V, Ga, Ge, As, Sb.

Properties

The crystal structure of sulfides is due to the densest cubic and hexagonal packing of S 2- ions, between which metal ions are located. the main structures are represented by coordination (galena, sphalerite), insular (pyrite), chain (antimonite) and layered (molybdenite) types.

The following general physical properties are characteristic: metallic luster, high and medium reflectivity, relatively low hardness and high specific gravity.

Origin (genesis)

They are widely distributed in nature, making up about 0.15% of the mass of the earth's crust. The origin is predominantly hydrothermal; some sulfides are also formed during exogenous processes in a reducing environment. They are ores of many metals - Cu, Ag, Hg, Zn, Pb, Sb, Co, Ni, etc. The class of sulfides includes antimonides, arsenides, selenides and tellurides close to them in properties.

Sulfides in nature

Under natural conditions, sulfur occurs in two valence states of the S 2 anion, which forms S 2- sulfides, and the S 6+ cation, which is included in the S0 4 sulfate radical.

As a result, the migration of sulfur in the earth's crust is determined by the degree of its oxidation: a reducing environment promotes the formation of sulfide minerals, and oxidizing conditions favor the formation of sulfate minerals. Neutral atoms of native sulfur represent a transitional link between two types of compounds, depending on the degree of oxidation or reduction.

Pyrite

Pyrite is a mineral, iron disulfide FeS 2, the most common sulfide in the earth's crust. Other names for the mineral and its varieties: cat's gold, fool's gold, iron pyrite, marcasite, bravoite. The sulfur content is usually close to theoretical (54.3%). Ni, Co impurities are often present (a continuous isomorphic series with CoS; usually, cobalt pyrite contains from tenths of % to several % of Co), Cu (from tenths of % to 10%), Au (often in the form of tiny inclusions of native gold), As (up to several%), Se, Tl (~ 10-2%), etc.

Properties

The color is light brassy and golden yellow, reminiscent of gold or chalcopyrite; sometimes contains microscopic inclusions of gold. Pyrite crystallizes in the cubic system. Crystals in the form of a cube, a pentagon-dodecahedron, less often an octahedron, are also found in the form of massive and granular aggregates.

Hardness on a mineralogical scale 6 - 6.5, density 4900-5200 kg / m3. On the surface of the Earth, pyrite is unstable, easily oxidized by atmospheric oxygen and groundwater, turning into goethite or limonite. Luster is strong, metallic.

Origin (genesis)

It is established in almost all types of geological formations. It is present as an accessory mineral in igneous rocks. It is usually an essential component in hydrothermal veins and metasomatic deposits (high-, medium- and low-temperature). In sedimentary rocks, pyrite occurs as grains and nodules, for example, in black shales, coals, and limestones. Sedimentary rocks are known, consisting mainly of pyrite and chert. Often forms pseudomorphs after fossil wood and ammonites.

Spreading

Pyrite is the most common mineral of the sulfide class in the earth's crust; occurs most often in deposits of hydrothermal origin, massive sulfide deposits. The largest industrial accumulations of pyrite ores are located in Spain (Rio Tinto), the USSR (Urals), Sweden (Bouliden). In the form of grains and crystals, it is distributed in metamorphic schists and other iron-bearing metamorphic rocks. Pyrite deposits are developed mainly to extract the impurities contained in it: gold, cobalt, nickel, copper. Some pyrite-rich deposits contain uranium (Witwatersrand, South Africa). Copper is also extracted from massive sulfide deposits in Ducktown (Tennessee, USA) and in the valley of the river. Rio Tinto (Spain). If there is more nickel in the mineral than iron, it is called bravoite. Oxidized, pyrite turns into limonite, so buried pyrite deposits can be detected by limonite (iron) hats on the surface. Main deposits: Russia, Norway, Sweden, France, Germany, Azerbaijan, USA.

Application

Pyrite ores are one of the main types of raw materials used to produce sulfuric acid and copper sulphate. Non-ferrous and precious metals are extracted from it along the way. Due to its ability to strike sparks, pyrite was used in the wheel locks of the first guns and pistols (steel-pyrite pair). Valuable collectible.

Pyrrhotite

Properties

Pyrrhotite is fiery red or dark orange in color, magnetic pyrites, a mineral from the class of sulfides of the Fe 1-x S composition. Ni, Co are included as impurities. The crystal structure has the densest hexagonal packing of S atoms.

The structure is defective, because not all octahedral voids are occupied by Fe, due to which a part of Fe 2+ has passed into Fe 3+ . The structural deficiency of Fe in pyrrhotite is different: it gives compositions from Fe 0.875 S (Fe 7 S 8) to FeS (the stoichiometric composition of FeS is troilite). Depending on the deficiency of Fe, the parameters and symmetry of the crystal cell change, and at x ~ 0.11 and below (up to 0.2), pyrotine from the hexagonal modification passes into the monoclinic one. The color of pyrrhotite is bronze-yellow with a brown tint; metallic luster. In nature, continuous masses, granular segregations, consisting of germinations of both modifications, are common.

Hardness on a mineralogical scale 3.5-4.5; density 4580-4700 kg/m3. The magnetic properties vary depending on the composition: hexagonal (poor S) pyrrhotites are paramagnetic, monoclinic (rich in S) are ferromagnetic. Separate pyrotine minerals have a special magnetic anisotropy - paramagnetism in one direction and ferromagnetism in the other, perpendicular to the first.

Origin (genesis)

Pyrrhotite is formed from hot solutions with a decrease in the concentration of dissociated S 2- ions.

It is widely distributed in hypogene deposits of copper-nickel ores associated with ultrabasic rocks; also in contact-metasomatic deposits and hydrothermal bodies with copper-polymetallic, sulfide-cassiterite, and other mineralization. In the oxidation zone it passes into pyrite, marcasite and brown iron ore.

Application

Plays an important role in the production of iron sulfate and crocus; as an ore for obtaining iron is less significant than pyrite. It is used in the chemical industry (production of sulfuric acid). Pyrrhotite usually contains impurities of various metals (nickel, copper, cobalt, etc.), which makes it interesting in terms of industrial applications. First, this mineral is an important iron ore. And secondly, some of its varieties are used as nickel ore. It is valued by collectors.

Marcasite

The name comes from the Arabic "marcasitae", which alchemists used to designate sulfur compounds, including pyrite. Another name is "radiant pyrite". Spectropyrite is named for its similarity to pyrite in color and iridescent tint.

Marcasite, like pyrite, is iron sulfide - FeS2, but differs from it in its internal crystalline structure, greater brittleness and lower hardness. Crystallizes in a rhombic crystal system. Marcasite is opaque, has a brassy-yellow color, often with a greenish or grayish tint, occurs in the form of tabular, acicular and spear-shaped crystals, which can form beautiful star-shaped radial-radiant intergrowths; in the form of spherical nodules (ranging in size from the size of a nut to the size of a head), sometimes sintered, kidney-shaped and grape-shaped formations, and crusts. Often replaces organic remains, such as ammonite shells.

Properties

The color of the trait is dark, greenish-gray, metallic luster. Hardness 5-6, brittle, imperfect cleavage. Marcasite is not very stable in surface conditions, over time, especially at high humidity, it decomposes, turning into limonite and releasing sulfuric acid, so it should be stored separately and with extreme care. When struck, marcasite emits sparks and a sulfur smell.

Origin (genesis)

In nature, marcasite is much less common than pyrite. It is observed in hydrothermal, predominantly veined deposits, most often in the form of druses of small crystals in voids, in the form of powders on quartz and calcite, in the form of crusts and sintered forms. In sedimentary rocks, mainly coal-bearing, sandy-clay deposits, marcasite occurs mainly in the form of nodules, pseudomorphs after organic remains, as well as finely dispersed sooty matter. Macroscopically, marcasite is often mistaken for pyrite. In addition to pyrite, marcasite is usually associated with sphalerite, galena, chalcopyrite, quartz, calcite, and others.

Place of Birth

Of the hydrothermal sulfide deposits, Blyavinskoye in the Orenburg region in the South Urals can be noted. Sedimentary deposits include Borovichi coal-bearing deposits of sandy clays (Novgorod region), containing various forms of concretions. The Kurya-Kamensky and Troitsko-Bainovsky deposits of clay deposits on the eastern slope of the Middle Urals (east of Sverdlovsk) are also famous for the variety of forms. Of note are deposits in Bolivia, as well as Clausthal and Freiberg (Westphalia, North Rhine, Germany), where well-formed crystals are found. In the form of concretions or especially beautiful, radially radiant flat lenses in once silty sedimentary rocks (clays, marls and brown coals), marcasite deposits were found in Bohemia (Czech Republic), the Paris Basin (France) and Styria (Austria, samples up to 7 cm). Marcasite is mined at Folkestone, Dover and Tavistock in the UK, in France, and in the US excellent specimens are obtained from Joplin and other locations in the TriState mining region (Missouri, Oklahoma and Kansas).

Application

In the case of large masses, marcasite can be developed for the production of sulfuric acid. Beautiful but fragile collectible material.

Oldgamite

Calcium sulfide, calcium sulfide, CaS - colorless crystals, density 2.58 g/cm3, melting point 2000 °C.

Receipt

Known as the mineral Oldgamite consisting of calcium sulfide with impurities of magnesium, sodium, iron, copper. The crystals are pale brown to dark brown.

Direct synthesis from elements:

The reaction of calcium hydride in hydrogen sulfide:

From calcium carbonate:

Recovery of calcium sulfate:

Physical properties

White crystals, cubic face-centered lattice of NaCl type (a=0.6008 nm). Decomposes when melted. In the crystal, each S 2- ion is surrounded by an octahedron consisting of six Ca 2+ ions, while each Ca 2+ ion is surrounded by six S 2- ions.

Slightly soluble in cold water, does not form crystalline hydrates. Like many other sulfides, calcium sulfide undergoes hydrolysis in the presence of water and smells like hydrogen sulfide.

Chemical properties

When heated, it decomposes into components:

Completely hydrolyzes in boiling water:

Diluted acids displace hydrogen sulfide from salt:

Concentrated oxidizing acids oxidize hydrogen sulfide:

Hydrogen sulfide is a weak acid and can be displaced from salts even by carbon dioxide:

With an excess of hydrogen sulfide, hydrosulfides are formed:

Like all sulfides, calcium sulfide is oxidized by oxygen:

Application

It is used for the preparation of phosphors, as well as in the leather industry to remove hair from hides, and is also used in the medical industry as a homeopathic remedy.

chemical weathering

Chemical weathering is a combination of various chemical processes that result in further destruction of rocks and a qualitative change in their chemical composition with the formation of new minerals and compounds. The most important chemical weathering factors are water, carbon dioxide and oxygen. Water is an energetic solvent of rocks and minerals.

The reaction that occurs during the roasting of iron sulfide in oxygen:

4FeS + 7O 2 → 2Fe 2 O 3 + 4SO 2

The reaction that occurs during the firing of iron disulfide in oxygen:

4FeS 2 + 11O 2 → 2Fe 2 O 3 + 8SO 2

When pyrite is oxidized under standard conditions, sulfuric acid is formed:

2FeS 2 +7O 2 +H 2 O→2FeSO 4 +H 2 SO 4

When calcium sulfide enters the furnace, the following reactions can occur:

2CaS + 3O 2 → 2CaO + 2SO 2

CaO + SO 2 + 0.5O 2 → CaSO 4

with the formation of calcium sulfate as the final product.

When calcium sulfide reacts with carbon dioxide and water, calcium carbonate and hydrogen sulfide are formed:

A 5-second activation of pyrite leads to a noticeable increase in the exotherm area, a decrease in the temperature range of oxidation, and a greater mass loss upon heating. Increasing the treatment time in the furnace up to 30 s causes stronger transformations of pyrite. The configuration of the DTA and the direction of the TG curves noticeably change, and the temperature ranges of oxidation continue to decrease. A break appears on the differential heating curve, corresponding to a temperature of 345 º C, which is associated with the oxidation of iron sulfates and elemental sulfur, which are the products of the oxidation of the mineral. The type of DTA and TG curves of a mineral sample treated for 5 min in an oven differs significantly from the previous ones. The new clearly pronounced exothermic effect on the differential heating curve with a temperature of about 305 º C should be attributed to the oxidation of neoplasms in the temperature range of 255 - 350 º C. The fact that the fraction obtained as a result of 5-minute activation is a mixture of phases.

Description and structure

Receipt

The reaction begins when a mixture of iron and sulfur is heated in a burner flame, then it can proceed without heating, with the release of heat.

$\backslash mathsf(Fe\_2O\_3\; +\; H\_2\; +\; 2H\_2S\; \backslash longrightarrow\; 2FeS\; +\; 3H\_2O)$

Chemical properties

1. Interaction with concentrated HCl:

$\backslash mathsf(FeS\; +\; 2HCl\; \backslash longrightarrow\; FeCl\_2\; +\; H\_2S)$

2. Interaction with concentrated HNO 3:

$\backslash mathsf(FeS\; +\; 12HNO\_3\; \backslash longrightarrow\; Fe(NO\_3)\_2\; +\; H\_2SO\_4\; +\; 9NO\_2\; +\; 5H\_2O)$

Application

Iron(II) sulfide is a common starting material in the production of hydrogen sulfide in the laboratory. Iron hydrosulfide and/or its corresponding basic salt is an essential component of some therapeutic muds.

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Notes

Literature

• Lidin R. A. “Handbook of a student. Chemistry "M.: Astrel, 2003.
• Nekrasov B.V. Fundamentals of General Chemistry. - 3rd edition. - Moscow: Chemistry, 1973. - T. 2. - S. 363. - 688 p.

Links

An excerpt characterizing Iron(II) sulfide

For a long time that night, Princess Marya sat by the open window in her room, listening to the sounds of peasants talking from the village, but she did not think about them. She felt that no matter how much she thought about them, she could not understand them. She kept thinking about one thing - about her grief, which now, after the break made by worries about the present, has already become past for her. She could now remember, she could cry and she could pray. As the sun went down, the wind died down. The night was calm and cool. At twelve o'clock the voices began to subside, a rooster crowed, the full moon began to emerge from behind the linden trees, a fresh, white dew mist rose, and silence reigned over the village and over the house.