Misplaced Pages

#508491

53-452: It then disproportionates into aluminium melt and aluminium trichloride upon cooling to 900 °C. This molecule has been detected in the interstellar medium , where molecules are so dilute that intermolecular collisions are unimportant. This inorganic compound –related article is a stub . You can help Misplaced Pages by expanding it . Disproportionation In chemistry , disproportionation , sometimes called dismutation ,

106-465: A component of bad breath odor. Not all organic sulfur compounds smell unpleasant at all concentrations: the sulfur-containing monoterpenoid grapefruit mercaptan in small concentrations is the characteristic scent of grapefruit, but has a generic thiol odor at larger concentrations. Sulfur mustard , a potent vesicant , was used in World War ;I as a disabling agent. Sulfur–sulfur bonds are

159-490: A disproportionation step in which a hydrogen atom is transferred from one growing chain molecule to another one, which produces two dead (non-growing) chains. in which, Chain— represents the already formed polymer chain, and indicates a reactive free radical . In 1937, Hans Adolf Krebs , who discovered the citric acid cycle bearing his name, confirmed the anaerobic dismutation of pyruvic acid into lactic acid , acetic acid and CO 2 by certain bacteria according to

212-572: A major industrial product, especially in automobile tires. Because of the heat and sulfur, the process was named vulcanization , after the Roman god of the forge and volcanism . Being abundantly available in native form, sulfur was known in ancient times and is referred to in the Torah ( Genesis ). English translations of the Christian Bible commonly referred to burning sulfur as "brimstone", giving rise to

265-416: A structural component used to stiffen rubber, similar to the disulfide bridges that rigidify proteins (see biological below). In the most common type of industrial "curing" or hardening and strengthening of natural rubber , elemental sulfur is heated with the rubber to the point that chemical reactions form disulfide bridges between isoprene units of the polymer. This process, patented in 1843, made rubber

318-433: A tracer in hydrologic studies. Differences in the natural abundances can be used in systems where there is sufficient variation in the S of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have measurably different S values than lakes believed to be dominated by watershed sources of sulfate. The radioactive S is formed in cosmic ray spallation of

371-400: Is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionation, such as when a compound in an intermediate oxidation state is formed from precursors of lower and higher oxidation states, is called comproportionation , also known as symproportionation . More generally,

424-482: Is a bright yellow, crystalline solid at room temperature . Sulfur is the tenth most abundant element by mass in the universe and the fifth most common on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals . Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India , ancient Greece , China , and ancient Egypt . Historically and in literature sulfur

477-465: Is a common reagent in organic synthesis . Bromine also oxidizes sulfur to form sulfur dibromide and disulfur dibromide . Sulfur oxidizes cyanide and sulfite to give thiocyanate and thiosulfate , respectively. Sulfur reacts with many metals. Electropositive metals give polysulfide salts. Copper, zinc, and silver are attacked by sulfur; see tarnishing . Although many metal sulfides are known, most are prepared by high temperature reactions of

530-511: Is a soft, bright-yellow solid that is odorless. It melts at 115.21 °C (239.38 °F), and boils at 444.6 °C (832.3 °F). At 95.2 °C (203.4 °F), below its melting temperature, cyclo-octasulfur begins slowly changing from α-octasulfur to the β- polymorph . The structure of the S 8 ring is virtually unchanged by this phase transition, which affects the intermolecular interactions. Cooling molten sulfur freezes at 119.6 °C (247.3 °F), as it predominantly consists of

583-599: Is about 2 g/cm , depending on the allotrope; all of the stable allotropes are excellent electrical insulators. Sulfur sublimes more or less between 20 °C (68 °F) and 50 °C (122 °F). Sulfur is insoluble in water but soluble in carbon disulfide and, to a lesser extent, in other nonpolar organic solvents, such as benzene and toluene . Under normal conditions, sulfur hydrolyzes very slowly to mainly form hydrogen sulfide and sulfuric acid : The reaction involves adsorption of protons onto S 8 clusters, followed by disproportionation into

SECTION 10

#1732859195509

636-451: Is also called brimstone , which means "burning stone". Almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum . The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers , and other chemical processes. Sulfur is used in matches , insecticides , and fungicides . Many sulfur compounds are odoriferous, and

689-495: Is an example of comproportionation reaction (the inverse of disproportionation) involving hydrogen sulfide ( H 2 S ) and sulfur dioxide ( SO 2 ) to produce elemental sulfur and water as follows: The Claus reaction is one of the chemical reactions involved in the Claus process used for the desulfurization of gases in the oil refinery plants and leading to the formation of solid elemental sulfur ( S 8 ), which

742-495: Is easier to store, transport, reuse when possible, and dispose of. Sulfur This is an accepted version of this page Sulfur (also spelled sulphur in British English ) is a chemical element ; it has symbol S and atomic number 16. It is abundant , multivalent and nonmetallic . Under normal conditions , sulfur atoms form cyclic octatomic molecules with the chemical formula S 8 . Elemental sulfur

795-417: Is explained by its production in the so-called alpha-process (one of the main classes of nuclear fusion reactions) in exploding stars. Other stable sulfur isotopes are produced in the bypass processes related with Ar, and their composition depends on a type of a stellar explosion. For example, proportionally more S comes from novae than from supernovae . On the planet Earth the sulfur isotopic composition

848-464: Is higher than the melting point of sulfur. Native sulfur is synthesized by anaerobic bacteria acting on sulfate minerals such as gypsum in salt domes . Significant deposits in salt domes occur along the coast of the Gulf of Mexico , and in evaporites in eastern Europe and western Asia. Native sulfur may be produced by geological processes alone. Fossil-based sulfur deposits from salt domes were once

901-559: Is involved and distinguish such processes from disproportionation and comproportionation. For example, the Schlenk equilibrium is an example of a redistribution reaction. The first disproportionation reaction to be studied in detail was: This was examined using tartrates by Johan Gadolin in 1788. In the Swedish version of his paper he called it söndring . In free-radical chain-growth polymerization , chain termination can occur by

954-573: Is mildly acidic: Hydrogen sulfide gas and the hydrosulfide anion are extremely toxic to mammals, due to their inhibition of the oxygen-carrying capacity of hemoglobin and certain cytochromes in a manner analogous to cyanide and azide (see below, under precautions ). The two principal sulfur oxides are obtained by burning sulfur: Many other sulfur oxides are observed including the sulfur-rich oxides include sulfur monoxide , disulfur monoxide , disulfur dioxides, and higher oxides containing peroxo groups. Sulfur reacts with fluorine to give

1007-399: Is produced by rapid cooling of molten sulfur—for example, by pouring it into cold water. X-ray crystallography studies show that the amorphous form may have a helical structure with eight atoms per turn. The long coiled polymeric molecules make the brownish substance elastic , and in bulk it has the feel of crude rubber. This form is metastable at room temperature and gradually reverts to

1060-557: Is the 10th most common element in the universe . Sulfur, usually as sulfide, is present in many types of meteorites . Ordinary chondrites contain on average 2.1% sulfur, and carbonaceous chondrites may contain as much as 6.6%. It is normally present as troilite (FeS), but there are exceptions, with carbonaceous chondrites containing free sulfur, sulfates and other sulfur compounds. The distinctive colors of Jupiter 's volcanic moon Io are attributed to various forms of molten, solid, and gaseous sulfur. In July 2024, elemental sulfur

1113-408: Is used as a reagent to make the polymer rayon and many organosulfur compounds. Unlike carbon monoxide , carbon monosulfide is stable only as an extremely dilute gas, found between solar systems. Organosulfur compounds are responsible for some of the unpleasant odors of decaying organic matter. They are widely known as the odorant in domestic natural gas, garlic odor, and skunk spray, as well as

SECTION 20

#1732859195509

1166-490: The Hershey-Chase experiment . Because of the weak beta activity of S, its compounds are relatively safe as long as they are not ingested or absorbed by the body. S is created inside massive stars, at a depth where the temperature exceeds 2.5×10  K, by the fusion of one nucleus of silicon plus one nucleus of helium. As this nuclear reaction is part of the alpha process that produces elements in abundance, sulfur

1219-411: The chemical energy in these complex biochemical systems are the same organic molecules simultaneously acting as reductant or oxidant . Another example of biochemical dismutation reaction is the disproportionation of acetaldehyde into ethanol and acetic acid . While in respiration electrons are transferred from substrate ( electron donor ) to an electron acceptor , in fermentation part of

1272-408: The noble gases . Sulfur polycations, S 2+ 8 , S 2+ 4 and S 2+ 16 are produced when sulfur is reacted with oxidizing agents in a strongly acidic solution. The colored solutions produced by dissolving sulfur in oleum were first reported as early as 1804 by C. F. Bucholz, but the cause of the color and the structure of the polycations involved was only determined in

1325-473: The sulfate minerals , such as gypsum (calcium sulfate), alunite (potassium aluminium sulfate), and barite (barium sulfate). On Earth, just as upon Jupiter's moon Io, elemental sulfur occurs naturally in volcanic emissions, including emissions from hydrothermal vents . The main industrial source of sulfur has become petroleum and natural gas . Common oxidation states of sulfur range from −2 to +6. Sulfur forms stable compounds with all elements except

1378-409: The (among others) protein keratin , found in outer skin, hair, and feathers. Sulfur is one of the core chemical elements needed for biochemical functioning and is an elemental macronutrient for all living organisms. Sulfur forms several polyatomic molecules. The best-known allotrope is octasulfur , cyclo-S 8 . The point group of cyclo-S 8 is D 4d and its dipole moment is 0 D. Octasulfur

1431-414: The 2010s, it was thought that sulfate reduction could fractionate sulfur isotopes up to 46 permil and fractionation larger than 46 permil recorded in sediments must be due to disproportionation of sulfur compounds in the sediment. This view has changed since the 2010s as experiments showed that sulfate-reducing bacteria can fractionate to 66 permil. As substrates for disproportionation are limited by

1484-530: The 3rd century, the Chinese had discovered that sulfur could be extracted from pyrite . Chinese Daoists were interested in sulfur's flammability and its reactivity with certain metals, yet its earliest practical uses were found in traditional Chinese medicine . The Wujing Zongyao of 1044 AD described various formulas for Chinese black powder , which is a mixture of potassium nitrate ( KNO 3 ), charcoal , and sulfur. Indian alchemists, practitioners of

1537-640: The Earth's past ( paleoenvironment ). Disproportionation of sulfur intermediates, being one of the processes affecting sulfur isotopes of sediments, has drawn attention from geoscientists for studying the redox conditions in the oceans in the past. Sulfate-reducing bacteria fractionate sulfur isotopes as they take in sulfate and produce sulfide . Prior to 2010s, it was thought that sulfate reduction could fractionate sulfur isotopes up to 46 ‰ and fractionation larger than 46 ‰ recorded in sediments must be due to disproportionation of sulfur intermediates in

1590-494: The activity of sulfate-reducing bacteria in the time of formation of the sample, or suggest the main sources of sulfur in ecosystems. However, there are ongoing discussions over the real reason for the δ S shifts, biological activity or postdeposit alteration. For example, when sulfide minerals are precipitated, isotopic equilibration among solids and liquid may cause small differences in the δ S values of co-genetic minerals. The differences between minerals can be used to estimate

1643-436: The atmospheric Ar . This fact may be used to verify the presence of recent (up to 1 year) atmospheric sediments in various materials. This isotope may be obtained artificially by different ways. In practice, the reaction Cl + n → S + p is used by irradiating potassium chloride with neutrons. The isotope S is used in various sulfur-containing compounds as a radioactive tracer for many biological studies, for example,

Aluminium monochloride - Misplaced Pages Continue

1696-648: The basis for commercial production in the United States, Russia, Turkmenistan, and Ukraine. Such sources have become of secondary commercial importance, and most are no longer worked but commercial production is still carried out in the Osiek mine in Poland. Common naturally occurring sulfur compounds include the sulfide minerals , such as pyrite (iron sulfide), cinnabar (mercury sulfide), galena (lead sulfide), sphalerite (zinc sulfide), and stibnite (antimony sulfide); and

1749-501: The composition of reaction products. While reaction between sulfur and oxygen under normal conditions gives sulfur dioxide (oxidation state +4), formation of sulfur trioxide (oxidation state +6) requires a temperature of 400–600 °C (750–1,100 °F) and presence of a catalyst. In reactions with elements of lesser electronegativity , it reacts as an oxidant and forms sulfides, where it has oxidation state −2. Sulfur reacts with nearly all other elements except noble gases, even with

1802-451: The crystalline molecular allotrope, which is no longer elastic. This process happens over a matter of hours to days, but can be rapidly catalyzed. Sulfur has 23 known isotopes , four of which are stable: S ( 94.99% ± 0.26% ), S ( 0.75% ± 0.02% ), S ( 4.25% ± 0.24% ), and S ( 0.01% ± 0.01% ). Other than S, with a half-life of 87 days, the radioactive isotopes of sulfur have half-lives less than 3 hours. The preponderance of S

1855-416: The elements. Geoscientists also study the isotopes of metal sulfides in rocks and sediment to study environmental conditions in the Earth's past. Some of the main classes of sulfur-containing organic compounds include the following: Compounds with carbon–sulfur multiple bonds are uncommon, an exception being carbon disulfide , a volatile colorless liquid that is structurally similar to carbon dioxide. It

1908-421: The global reaction: The dismutation of pyruvic acid in other small organic molecules (ethanol + CO 2 , or lactate and acetate, depending on the environmental conditions) is also an important step in fermentation reactions. Fermentation reactions can also be considered as disproportionation or dismutation biochemical reactions . Indeed, the donor and acceptor of electrons in the redox reactions supplying

1961-406: The highly reactive sulfur tetrafluoride and the highly inert sulfur hexafluoride . Whereas fluorine gives S(IV) and S(VI) compounds, chlorine gives S(II) and S(I) derivatives. Thus, sulfur dichloride , disulfur dichloride , and higher chlorosulfanes arise from the chlorination of sulfur. Sulfuryl chloride and chlorosulfuric acid are derivatives of sulfuric acid; thionyl chloride (SOCl 2 )

2014-484: The largest documented single crystal measuring 22 cm × 16 cm × 11 cm (8.7 in × 6.3 in × 4.3 in). Historically, Sicily was a major source of sulfur in the Industrial Revolution . Lakes of molten sulfur up to about 200 m (660 ft) in diameter have been found on the sea floor, associated with submarine volcanoes , at depths where the boiling point of water

2067-415: The late 1960s. S 2+ 8 is deep blue, S 2+ 4 is yellow and S 2+ 16 is red. Reduction of sulfur gives various polysulfides with the formula S x , many of which have been obtained in crystalline form. Illustrative is the production of sodium tetrasulfide : Some of these dianions dissociate to give radical anions , such as S − 3 gives the blue color of

2120-573: The notoriously unreactive metal iridium (yielding iridium disulfide ). Some of those reactions require elevated temperatures. Sulfur forms over 30 solid allotropes , more than any other element. Besides S 8 , several other rings are known. Removing one atom from the crown gives S 7 , which is of a deeper yellow than S 8 . HPLC analysis of "elemental sulfur" reveals an equilibrium mixture of mainly S 8 , but with S 7 and small amounts of S 6 . Larger rings have been prepared, including S 12 and S 18 . Amorphous or "plastic" sulfur

2173-407: The product of sulfate reduction , the isotopic effect of disproportionation should be less than 16 permil in most sedimentary settings. In forest ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporites contribute some sulfur. Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as

Aluminium monochloride - Misplaced Pages Continue

2226-420: The reaction products. The second, fourth and sixth ionization energies of sulfur are 2252 kJ/mol, 4556 kJ/mol and 8495.8 kJ/mol, respectively. The composition of reaction products of sulfur with oxidants (and its oxidation state) depends on whether releasing of reaction energy overcomes these thresholds. Applying catalysts and/or supply of external energy may vary sulfur's oxidation state and

2279-509: The rock lapis lazuli . This reaction highlights a distinctive property of sulfur: its ability to catenate (bind to itself by formation of chains). Protonation of these polysulfide anions produces the polysulfanes , H 2 S x , where x = 2, 3, and 4. Ultimately, reduction of sulfur produces sulfide salts: The interconversion of these species is exploited in the sodium–sulfur battery . Treatment of sulfur with hydrogen gives hydrogen sulfide . When dissolved in water, hydrogen sulfide

2332-581: The sediment. This view has changed since the 2010s. As substrates for disproportionation are limited by the product of sulfate reduction , the isotopic effect of disproportionation should be less than 16 ‰ in most sedimentary settings. Disproportionation can be carried out by microorganisms obligated to disproportionation or microorganisms that can carry out sulfate reduction as well. Common substrates for disproportionation include elemental sulfur ( S 8 ), thiosulfate ( S 2 O 2− 3 ) and sulfite ( SO 2− 3 ). The Claus reaction

2385-719: The smells of odorized natural gas, skunk scent, bad breath , grapefruit , and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes. Sulfur is an essential element for all life, almost always in the form of organosulfur compounds or metal sulfides. Amino acids (two proteinogenic : cysteine and methionine , and many other non-coded : cystine , taurine , etc.) and two vitamins ( biotin and thiamine ) are organosulfur compounds crucial for life. Many cofactors also contain sulfur, including glutathione , and iron–sulfur proteins . Disulfides , S–S bonds, confer mechanical strength and insolubility of

2438-476: The substrate molecule itself accepts the electrons. Fermentation is therefore a type of disproportionation, and does not involve an overall change in oxidation state of the substrate. Most of the fermentative substrates are organic molecules. However, a rare type of fermentation may also involve the disproportionation of inorganic sulfur compounds in certain sulfate-reducing bacteria . Sulfur isotopes of sediments are often measured for studying environments in

2491-465: The temperature of equilibration. The δ C and δ S of coexisting carbonate minerals and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during ore formation. Scientists measure the sulfur isotopes of minerals in rocks and sediments to study the redox conditions in past oceans. Sulfate-reducing bacteria in marine sediment fractionate sulfur isotopes as they take in sulfate and produce sulfide . Prior to

2544-505: The term " fire-and-brimstone " sermons , in which listeners are reminded of the fate of eternal damnation that await the unbelieving and unrepentant. It is from this part of the Bible that Hell is implied to "smell of sulfur" (likely due to its association with volcanic activity). According to the Ebers Papyrus , a sulfur ointment was used in ancient Egypt to treat granular eyelids. Sulfur

2597-451: The term can be applied to any desymmetrizing reaction where two molecules of one type react to give one each of two different types: This expanded definition is not limited to redox reactions, but also includes some molecular autoionization reactions, such as the self-ionization of water . In contrast, some authors use the term redistribution to refer to reactions of this type (in either direction) when only ligand exchange but no redox

2650-419: The β-S 8 molecules. Between its melting and boiling temperatures, octasulfur changes its allotrope again, turning from β-octasulfur to γ-sulfur, again accompanied by a lower density but increased viscosity due to the formation of polymers . At higher temperatures, the viscosity decreases as depolymerization occurs. Molten sulfur assumes a dark red color above 200 °C (392 °F). The density of sulfur

2703-615: Was accidentally discovered to exist on Mars after the Curiosity rover drove over and crushed a rock, revealing sulfur crystals inside it. Sulfur is the fifth most common element by mass in the Earth. Elemental sulfur can be found near hot springs and volcanic regions in many parts of the world, especially along the Pacific Ring of Fire ; such volcanic deposits are mined in Indonesia, Chile, and Japan. These deposits are polycrystalline, with

SECTION 50

#1732859195509

2756-549: Was determined by the Sun. Though it was assumed that the distribution of different sulfur isotopes would be more or less equal, it has been found that proportions of the two most abundant sulfur isotopes S and S varies in different samples. Assaying of the isotope ratio ( δ S ) in the samples suggests their chemical history, and with support of other methods, it allows to age-date the samples, estimate temperature of equilibrium between ore and water, determine pH and oxygen fugacity , identify

2809-622: Was used for fumigation in preclassical Greece ; this is mentioned in the Odyssey . Pliny the Elder discusses sulfur in book 35 of his Natural History , saying that its best-known source is the island of Melos . He mentions its use for fumigation, medicine, and bleaching cloth. A natural form of sulfur known as shiliuhuang ( 石硫黄 ) was known in China since the 6th century BC and found in Hanzhong . By

#508491