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Sulfur (US English) or sulphur is the chemical element with atomic number 16. In theperiodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow crystalline solid when at room temperature. Sony VAIO VGN-CS120J/Q Battery

Chemically, sulfur can react as either an oxidant or reducing agent. It oxidizes most metals and severalnonmetals, including carbon, which leads to its negative charge in most organosulfur compounds, but it reduces several strong oxidants, such as oxygen and fluorine. It is also the lightest element to easily produce stable exceptions to the octet rule.Sony VAIO VGN-CS120J/R Battery

In nature, sulfur can be found as the pure element and as sulfide and sulfate minerals. Elemental sulfur crystals are commonly sought after by mineral collectors for their brightly colored polyhedron shapes. Being abundant in native form, sulfur was known in ancient times, mentioned for its uses in ancient Greece, China and Egypt.Sony VAIO VGN-CS190JTB Battery

Sulfur fumes were used as fumigants, and sulfur-containing medicinal mixtures were used as balms and antiparasitics. Sulfur is referenced in the Bibleas brimstone in English, with this name still used in several nonscientific terms.[2] Sulfur was considered important enough to receive its own alchemical symbol. Sony VAIO VGN-CS190JTP Battery

It was needed to make the best quality of black gunpowder, and the bright yellow powder was hypothesized by alchemists to contain some of the properties of gold, which they sought to synthesize from it. In 1777,Antoine Lavoisier helped convince the scientific community that sulfur was a basic element, rather than a compound.Sony VAIO VGN-CS190JTQ Battery

Elemental sulfur was once extracted from salt domes where it sometimes occurs in nearly pure form, but this method has been obsolete since the late 20th century. Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. Sony VAIO VGN-CS190JTR Battery

The element's commercial uses are primarily in fertilizers, because of the relatively high requirement of plants for it, and in the manufacture of sulfuric acid, a primary industrial chemical. Other well-known uses for the element are in matches, insecticides and fungicides. Sony VAIO VGN-CS190JTW Battery

Many sulfur compounds are odiferous, and the smell of odorized natural gas, skunk scent, grapefruit, and garlic is due to sulfur compounds. Hydrogen sulfide produced by living organisms imparts the characteristic odor to rotting eggs and other biological processes.Sony VAIO VGN-CS190NAB Battery

Sulfur is an essential element for all life, and is widely used in biochemical processes. In metabolic reactions, sulfur compounds serve as both fuels and respiratory (oxygen-replacing) materials for simple organisms. Sulfur in organic form is present in the vitamins biotin and thiamine, the latter being named for the Greek word for sulfur.Sony VAIO VGN-CS190NAC Battery

Sulfur is an important part of many enzymes and in antioxidant molecules like glutathione and thioredoxin. Organically bonded sulfur is a component of all proteins, as the amino acids cysteine and methionine. Disulfide bonds are largely responsible for the mechanical strength and insolubility of the protein keratin, found in outer skin, hair, and feathers, and the element contributes to their pungent odor when burned.Sony VAIO VGN-CS190NAD Battery

Physical

Sulfur forms polyatomic molecules with different chemical formulas, with the best-known allotrope being octasulfur, cyclo-S8. Octasulfur is a soft, bright-yellow solid with only a faint odor, similar to that of matches.[3] It melts at 115.21 °C, boils at 444.6 °C and sublimes easily.Sony VAIO VGN-CS190NBB Battery

At 95.2 °C, below its melting temperature, cyclo-octasulfur changes from ?-octasulfur to the ?-polymorph.The structure of the S8ring is virtually unchanged by this phase change, which affects the intermolecular interactions. Between its melting and boiling temperatures, octasulfur changes its allotrope again, turning from ?-octasulfur to ?-sulfur, again accompanied by a lower density but increased viscosity due to the formation of polymers.Sony VAIO VGN-CS190NCA Battery

At even higher temperatures, however, the viscosity decreases as depolymerization occurs. Molten sulfur assumes a dark red color above 200 °C. The density of sulfur is about 2 g·cm?3, depending on the allotrope; all of its stable allotropes are excellent electrical insulators.Sony VAIO VGN-CS190NCB Battery

Chemical

Sulfur burns with a blue flame concomitant with formation of sulfur dioxide, notable for its peculiar suffocating odor. Sulfur is insoluble in water but soluble in carbon disulfide and, to a lesser extent, in other nonpolar organic solvents, such as benzene andtoluene. Sony VAIO VGN-CS190NCC Battery

The first and the second ionization energies of sulfur are 999.6 and 2252 kJ·mol?1, respectively. Despite such figures, S2+ is rare, S4, 6+ being more common. The fourth and sixth ionization energies are 4556 and 8495.8 kJ·mol?1, the magnitude of the figures caused by electron transfer between orbitals; these states are only stable with strong oxidants as fluorine, oxygen, and chlorine.Sony VAIO VGN-CS50B/W Battery

Allotropes

Sulfur forms more than 30 solid allotropes, more than any other element. Besides S8, several other rings are known. Removing one atom from the crown gives S7, which is more deeply yellow than S8. HPLC analysis of "elemental sulfur" reveals an equilibrium mixture of mainly S8, but with S7 and small amounts of S6.Sony VAIO VGN-CS51B/W Battery

Larger rings have been prepared, including S12 and S18.

Amorphous or "plastic" sulfur 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. Sony VAIO VGN-CS52JB/W Battery

The long coiled polymeric molecules cause the brownish substance to be elastic, and in bulk this form has the feel of crude rubber. This form is metastable at room temperature and gradually reverts to crystalline molecular allotrope, which is no longer elastic. This process happens within a matter of hours to days, but can be rapidly catalyzed.Sony VAIO VGN-CS60B/P Battery

Isotopes

Sulfur has 25 known isotopes, four of which are stable: 32S (95.02%), 33S (0.75%), 34S (4.21%), and 36S (0.02%). Other than 35S, with a half-life of 87 days and formed in cosmic ray spallation of 40Ar, the radioactive isotopes of sulfur have half-lives less than 170 minutes.Sony VAIO VGN-CS60B/Q Battery

When sulfide minerals are precipitated, isotopic equilibration among solids and liquid may cause small differences in the ?S-34 values of co-genetic minerals. The differences between minerals can be used to estimate the temperature of equilibration.Sony VAIO VGN-CS60B/R Battery

The ?C-13 and ?S-34 of coexisting carbonates and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during ore formation.

In most forest ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporites contribute some sulfur. Sony VAIO VGN-CS61B/P Battery

Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in hydrologic studies. Differences in the natural abundances can be used in systems where there is sufficient variation in the 34S of ecosystem components. Sony VAIO VGN-CS61B/Q Battery

Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different ?34S values from lakes believed to be dominated by watershed sources of sulfate.

Natural occurrence

32S is created inside massive stars, at a depth where the temperature exceeds 2.5×109 K, by the fusion of one nucleus of silicon plus one nucleus of helium.Sony VAIO VGN-CS61B/R Battery

As this is part of the alpha process that produces elements in abundance, sulfur 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%.Sony VAIO VGN-CS62JB/P Battery

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'svolcanic moon Io are attributed to various forms of molten, solid and gaseous sulfur.Sony VAIO VGN-CS62JB/Q Battery

On Earth, elemental sulfur can be found near hot springs and volcanic regions in many parts of the world, especially along thePacific Ring of Fire; such volcanic deposits are currently mined in Indonesia, Chile, and Japan. Such deposits are polycrystalline, with the largest documented single crystal measuring 22×16×11 cm.Sony VAIO VGN-CS62JB/R Battery

Historically, Sicily was a large source of sulfur in the Industrial Revolution.

Significant deposits of elemental sulfur, believed to have been (and are still being) synthesised by anaerobic bacteria on sulfate minerals like gypsum, exist in salt domes 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.Sony VAIO VGN-CS71B/W Battery

Fossil-based sulfur deposits from salt domes have until recently been the basis for commercial production in the United States, Poland, Russia, Turkmenistan, and Ukraine. Such sources are now of secondary commercial importance, and most are no longer worked.Sony VAIO VGN-CS72JB/W Battery

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 the sulfates, such as gypsum (calcium sulfate), alunite (potassium aluminium sulfate), and barite (barium sulfate). Sony VAIO VGN-CS90HS Battery

On Earth, just as upon Jupiter's moon Io, elemental sulfur occurs naturally in volcanic emissions, including emissions from hydrothermal vents.

Production

Sulfur may be found by itself and historically was usually obtained in this way, while pyrite has been a source of sulfur via sulfuric acid.Sony VAIO VGN-CS90NS Battery

The Sicilian process was used in ancient times to obtain sulfur from rocks present in volcanic regions ofSicily: sulfur deposits were piled and stacked in brick kilns built on sloping hillsides, with airspaces between them. Then, powdered sulfur was put on top of the deposit and ignited, causing the deposits to melt down the hills. Sony VAIO VGN-CS90S Battery

Today's sulfur production is as a side product of other industrial processes such as oil refining; in these processes, sulfur often occurs as undesired or detrimental compounds that are extracted and converted to elemental sulfur. As a mineral, native sulfur under salt domes is thought to be a fossil mineral resource, produced by the action of ancient bacteria on sulfate deposits. Sony VAIO VGN-CS91HS Battery

It was removed from such salt-dome mines mainly by the Frasch process. In this method, superheated water was pumped into a native sulfur deposit to melt the sulfur, and then compressed air returned the 99.5% pure melted product to the surface. Sony VAIO VGN-CS91NS Battery

Throughout the 20th century this procedure produced elemental sulfur which required no further purification. However, due to a limited number of such sulfur deposits and the high cost of working them, this process for mining sulfur has not been employed in a major way anywhere in the world since 2002.Sony VAIO VGN-CS91S Battery

Today, sulfur is produced from petroleum, natural gas, and related fossil resources, from which it is obtained mainly ashydrogen sulfide. Organosulfur compounds, undesirable impurities in petroleum, may be upgraded by subjecting them tohydrodesulfurization, which cleaves the C–S bonds:Sony VAIO VGN-CS92DS Battery

R-S-R + 2 H2 ? 2 RH + H2S

The resulting hydrogen sulfide from this process, and also as it occurs in natural gas, is converted into elemental sulfur by theClaus process. This process entails oxidation of some hydrogen sulfide to sulfur dioxide and then the comproportionation of the two:Sony VAIO VGN-CS92JS Battery

3 O2 + 2 H2S ? 2 SO2 + 2 H2O
SO2 + 2 H2S ? 3 S + 2 H2O

Owing to the high sulfur content of the Athabasca Oil Sands, stockpiles of elemental sulfur from this process now exist throughoutAlberta, Canada. Another way of storing sulfur is as a binder for concrete, the resulting product having many desirable properties. The price of sulfur increased from 2007 to 2008, and decreased thereafter.Sony VAIO VGN-CS92XS Battery

Compounds

Common oxidation states of sulfur range from ?2 to +6. Sulfur forms stable compounds with all elements except the noble gases.

Sulfides

Treatment of sulfur with hydrogen gives hydrogen sulfide. When dissolved in water, hydrogen sulfide is mildly acidic:Sony VAIO VGN-FW11E Battery

H2S \overrightarrow{\leftarrow} HS– + H+

Hydrogen sulfide gas and the dissolved sulfide and hydrosulfide anions 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, underprecautions).Sony VAIO VGN-FW11L Battery

Reduction of elemental sulfur gives polysulfides, which consist of chains of sulfur atoms terminated with S– centers:

2 Na + S8 ? Na2S8

This reaction highlights arguably the single most distinctive property of sulfur: its ability to catenate (bind to itself by formation of chains). Sony VAIO VGN-FW11M Battery

Protonation of these polysulfide anions gives the polysulfanes, H2Sx where x = 2, 3, and 4. Ultimately reduction of sulfur gives sulfide salts:

16 Na + S8 ? 8 Na2S

The interconversion of these species is exploited in the sodium-sulfur battery. The radical anion S3– gives the blue color to the mineral lapis lazuli.Sony VAIO VGN-FW11S Battery

Elemental sulfur can be oxidized, for example, to give bicyclic S82+.

Oxides and oxyanions

The principal sulfur oxides are obtained by burning sulfur:

S + O2 ? SO2
2 SO2 + O2 ? 2 SO3

Other oxides are known, e.g. sulfur monoxide and disulfur mono- and dioxides, but they are unstable.Sony VAIO VGN-FW11ZU Battery

The sulfur oxides form numerous oxyanions with the formula SOn2–. Sulfur dioxide and sulfites (SO2?3) are related to the unstable sulfurous acid (H2SO3). Sulfur trioxide and sulfates (SO2?4) are related to sulfuric acid. Sulfuric acid and SO3 combine to give oleum, a solution of pyrosulfuric acid (H2S2O7) in sulfuric acid.Sony VAIO VGN-FW139E/H Battery

Peroxides convert sulfur into unstable such as S8O, a sulfoxide. Peroxymonosulfuric acid (H2SO5) and peroxydisulfuric acids (H2S2O8), made from the action of SO3 on concentrated H2O2, and H2SO4 on concentrated H2O2 respectively.Sony VAIO VGN-FW140AE Battery

Thiosulfate salts (S2O2?3), sometimes referred as "hyposulfites", used in photographic fixing (HYPO) and as reducing agents, feature sulfur in two oxidation states. Sodium dithionite, (S2O2?4), contains the more highly reducing dithionite anion. Sodium dithionate(Na2S2O6) is the first member of the polythionic acids (H2SnO6), where n can range from 3 to many.Sony VAIO VGN-FW140D Battery

Halides and oxyhalides

The two main sulfur fluorides are sulfur hexafluoride, a dense gas used as nonreactive and nontoxic propellant, and sulfur tetrafluoride, a rarely used organic reagent that is highly toxic. Their chlorinated analogs are sulfur dichloride and sulfur monochloride.Sony VAIO VGN-FW140E Battery

Sulfuryl chloride and chlorosulfuric acid are derivatives of sulfuric acid; thionyl chloride (SOCl2) is a common reagent inorganic synthesis.

Pnictides

The most important S–N compound is the cage tetrasulfur tetranitride (S4N4). Sony VAIO VGN-FW140E/H Battery

Heating this compound gives polymeric sulfur nitride((SN)x), which has metallic properties even though it does not contain any metal atoms. Thiocyanates contain the SCN? group. Oxidation of thiocyanate gives thiocyanogen, (SCN)2 with the connectivity NCS-SCN. Phosphorus sulfides are numerous, the most important commercially being the cages P4S10 and P4S3.Sony VAIO VGN-FW140E/W Battery

Metal sulfides

Many if not most minerals occur as sulfides. The principal ores of copper, zinc, nickel, cobalt, molybdenum and others are sulfides. These materials tend to be dark-colored semiconductors that are not readily attacked by water or even many acids. Sony VAIO VGN-FW140FE Battery

They are formed, both geochemically and in the laboratory, by the reaction of hydrogen sulfide with metal salts to form the metal sulfides. The mineral galena (PbS) was the first demonstrated semiconductor and found a use as a signal rectifier in the cat's whiskers of early crystal radios.Sony VAIO VGN-FW140N Battery

The iron sulfide called pyrite, the so-called "fool's gold," has the formula FeS2. The upgrading of these ores, usually by roasting, is costly and environmentally hazardous. Sulfur corrodes many metals via the process called tarnishing.

Some of the main classes of sulfur-containing organic compounds include the following:Sony VAIO VGN-FW140N/W Battery

  • Thiols or mercaptans (as they are mercury capturers as chelators) are the sulfur analogs of alcohols; treatment of thiols with base gives thiolate ions.
  • Thioethers are the sulfur analogs of ethers.
  • Sulfonium ions have three groups attached to a cationic sulfur center. Dimethylsulfoniopropionate (DMSP) is one such compound, important in the marine organicsulfur cycle.Sony VAIO VGN-FW145E Battery
  • Sulfoxides and sulfones are thioethers with one and two oxygen atoms attached to the sulfur atom, respectively. The simplest sulfoxide, dimethyl sulfoxide, is a common solvent; a common sulfone is sulfolane.
  • Sulfonic acids are used in many detergents.Sony VAIO VGN-FW145E/W Battery

Some inorganic compounds with carbon–sulfur bonds are known. Carbon disulfide, a volatile colorless liquid at standard conditions, is structurally similar to carbon dioxide; it is used as a solvent to make polymers. Whereas carbon monoxide is highly stable, carbon monosulfide is unstable and has only been observed as a gas and in the interstellar medium.Sony VAIO VGN-FW160AE Battery

Organosulfur compounds are responsible for the some of the unpleasant odors of decaying organic matter. They are used in the odoration of natural gas and cause the odor of garlic and skunk spray. Not all organic sulfur compounds smell unpleasant at all concentrations:Sony VAIO VGN-FW160D Battery

the sulfur-containing monoterpenoid grapefruit mercaptan in small concentrations is responsible for the characteristic scent of grapefruit, but has a generic thiol odor at larger concentrations. Sulfur mustard, a potentvesicant, was used in World War I as a disabling agent.Sony VAIO VGN-FW160E Battery

Sulfur can be used in organics as a structural component to harden synthetic polymers, in a way similar to the biological use of disulfide bridges to reinforce proteins (see biological below). In the most common type of industrial "curing" or hardening and strengthening of natural rubber,Sony VAIO VGN-FW160E/H Battery

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, historically changed rubber into a major industrial product. The process was named vulcanization after the Roman god of the forge and volcanism, in honor of both the heat and sulfur used. Sony VAIO VGN-FW160F/E Battery

Although vulcanization is applied to other polymers, and sometimes with crosslinking agents other than sulfur, variants of sulfur/rubber vulcanization continue to be used in producing automobile tires and other elastomer products.Sony VAIO VGN-FW170J/H Battery

Antiquity

Being abundantly available in native form, sulfur (Latin sulphur) was known in ancient times and is referred to in the Torah (Genesis). English translations of the Bible commonly referred to burning sulfur as "brimstone", giving rise to the name of 'fire-and-brimstone' sermons, Sony VAIO VGN-FW180AE Battery

in which listeners are reminded of the fate ofeternal 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.Sony VAIO VGN-FW180D Battery

Sulfur was used for fumigation in preclassical Greece;[31] this is mentioned in the Odyssey.[32] 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.Sony VAIO VGN-FW180E Battery

A natural form of sulfur known as shiliuhuang was known in China since the 6th century BC and found in Hanzhong. By the 3rd century, the Chinese 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.Sony VAIO VGN-FW180E/H Battery

A Song Dynasty military treatise of 1044 AD described different formulas for Chinese black powder, which is a mixture of potassium nitrate (KNO3), charcoal, and sulfur.

Early alchemists gave sulfur its own alchemical symbol which was a triangle at the top of a cross. Sony VAIO VGN-FW180FU Battery

In traditional medical skin treatment which predates modern era of scientific medicine, elemental sulfur has been used mainly as part of creams to alleviate various conditions such as scabies, ringworm, psoriasis, eczema and acne. The mechanism of action is not known, although elemental sulfur does oxidize slowly to sulfurous acid, which in turn (through the action of sulfite) acts as a mild reducing and antibacterial agent. Sony VAIO VGN-FW190EBH Battery

Modern times

In 1777, Antoine Lavoisier helped convince the scientific community that sulfur was an element, not a compound. With the sulfur from Sicily being principally controlled by the French market, a debate ensued about the amount of sulfur France and Britain got. This led to a bloodless confrontation between the two sides in 1840.Sony VAIO VGN-FW190ECH Battery

In 1867, sulfur was discovered in underground deposits inLouisiana and Texas. The highly successful Frasch process was developed to extract this resource.

In the late 18th century, furniture makers used molten sulfur to produce decorative inlays in their craft. Sony VAIO VGN-FW190EDH Battery

Because of the sulfur dioxide produced during the process of melting sulfur, the craft of sulfur inlays was soon abandoned. Molten sulfur is sometimes still used for setting steel bolts into drilled concrete holes where high shock resistance is desired for floor-mounted equipment attachment points. Pure powdered sulfur was used as a medicinal tonic and laxative.Sony VAIO VGN-FW190NAH Battery

With the advent of the contact process, the majority of sulfur today is used to make sulfuric acid for a wide range of uses, particularly fertilizer.

Spelling and etymology

Sulfur comes from the Old French soufre, apparently referring from a root meaning "to burn".Sony VAIO VGN-FW190NBH Battery

The element was traditionally spelled sulphur in the United Kingdom (since the 14th century), most of the Commonwealth including India, Malaysia, South Africa, and Hong Kong, along with the rest of the Caribbean and Ireland. Sulfur is used in the United States, while both spellings are used in Canada and the Philippines.Sony VAIO VGN-FW190NCH Battery

However, the IUPAC adopted the spelling sulfur in 1990, as did the Royal Society of Chemistry Nomenclature Committee in 1992.The Qualifications and Curriculum Authority for England and Wales recommended its use in 2000, and it now appears in GCSE exams.Sony VAIO VGN-FW190NDH Battery

The Oxford Dictionaries note that "In chemistry... the -f- spelling is now the standard form in all related words in the field in both British and US contexts"

In Latin, the word is variously written sulpur, sulphur, and sulfur (the Oxford Latin Dictionary lists the spellings in this order). Sony VAIO VGN-FW190NEH Battery

It is an original Latin name and not a Classical Greek loan, so the ph variant does not denote the Greek letter ? (phi). Sulfur in Greek is thion (?????), whence comes the prefix thio-. The simplification of the Latin words p or ph to an f appears to have taken place towards the end of the classical period.Sony VAIO VGN-FW198U/H Battery

Sulfuric acid

Elemental sulfur is mainly used as a precursor to other chemicals. Approximately 85% (1989) is converted to sulfuric acid (H2SO4):

2 S + 3 O2 + 2 H2O ? 2 H2SO4

With sulfuric acid being central importance to the world's economies, its production and consumption is an indicator of a nation's industrial development.Sony VAIO VGN-FW260J/B Battery

For example with 36.1 million metric tons in 2007, the United States produces more sulfuric acid every year than any other inorganic industrial chemical. The principal use for the acid is the extraction of phosphate ores for the production of fertilizer manufacturing. Sony VAIO VGN-FW280J/H Battery

Other applications of sulfuric acid include oil refining, wastewater processing, and mineral extraction.

Other large scale sulfur chemicals

Sulfur reacts directly with methane to give carbon disulfide, which is used to manufacture cellophane and rayon. One of the direct uses of sulfur is invulcanization of rubber, where polysulfides crosslink organic polymers. Sony VAIO VGN-FW290JRB Battery

Sulfites are heavily used to bleach paper and as preservatives in dried fruit. Manysurfactants and detergents, e.g. sodium lauryl sulfate, are produced are sulfate derivatives. Calcium sulfate, gypsum, (CaSO4·2H2O) is mined on the scale of 100 million tons each year for use in Portland cement and fertilizers.Sony VAIO VGN-FW290JTB Battery

When silver-based photography was widespread, sodium and ammonium thiosulfate were widely used as "fixing agents." Sulfur is a component of gunpowder.

Fertilizer

Sulfur is increasingly used as a component of fertilizers. The most important form of sulfur for fertilizer is the mineral calcium sulfate.Sony VAIO VGN-FW290JTH Battery

Elemental sulfur is hydrophobic (that is, it is not soluble in water) and therefore cannot be directly utilized by plants. Over time, soil bacteria can convert it to soluble derivatives which can then be utilized by plants. Sulfur improves the use efficiency of other essential plant nutrients, particularly nitrogen and phosphorus.Sony VAIO VGN-FW290JTW Battery

Biologically produced sulfur particles are naturally hydrophilic due to a biopolymer coating. This sulfur is therefore easier to disperse over the land (via spraying as a diluted slurry), and results in a faster release.

Plant requirements for sulfur are equal to or exceed those for phosphorus.Sony VAIO VGN-FW355J/H Battery

It is one of the major nutrients essential for plant growth, root nodule formation of legumes and plants protection mechanisms. Sulfur deficiency has become widespread in many countries in Europe. Because atmospheric inputs of sulfur will continue to decrease, the deficit in the sulfur input/output is likely to increase, unless sulfur fertilizers are used.Sony VAIO VGN-FW373J/B Battery

Fine chemicals

Organosulfur compounds are used in pharmaceuticals, dyestuffs, and agrochemicals. Many drugs contain sulfur, early examples being antibacterial sulfonamides, known as sulfa drugs. Sulfur is a part of many bacterial defense molecules. Most ?-lactamantibiotics, including the penicillins, cephalosporins and monolactams contain sulfur.Sony VAIO VGN-FW30B Battery

Magnesium sulfate, known as Epsom salts when in hydrated crystal form, can be used as a laxative, a bath additive, an exfoliant,magnesium supplement for plants, or (when in dehydrated form) as a desiccant.Sony VAIO VGN-FW50B Battery

Fungicide and pesticide

Elemental sulfur is one of the oldest fungicides and pesticides. "Dusting sulfur," elemental sulfur in powdered form, is a common fungicide for grapes, strawberry, many vegetables and several other crops. It has a good efficacy against a wide range of powdery mildew diseases as well as black spot.Sony VAIO VGN-FW51B/W Battery

In organic production, sulfur is the most important fungicide. It is the only fungicide used in organically farmed apple production against the main disease apple scab under colder conditions. Biosulfur (biologically produced elemental sulfur with hydrophilic characteristics) can be used well for these applications.Sony VAIO VGN-FW51MF Battery

Standard-formulation dusting sulfur is applied to crops with a sulfur duster or from a dusting plane. Wettable sulfur is the commercial name for dusting sulfur formulated with additional ingredients to make it water miscible. It has similar applications and is used as a fungicide against mildew and other mold-related problems with plants and soil.Sony VAIO VGN-FW51MF/H Battery

Elemental sulfur powder is used as an "organic" (i.e. "green") insecticide (actually an acaricide) against ticks and mites. A common method of use is to dust clothing or limbs with sulfur powder.

Diluted solutions of lime sulfur (made by combinding calcium hydroxide with elemental sulfur in water), are used as a dip for pets to destroy ringworm (fungus),mange and other dermatoses and parasites.Sony VAIO VGN-FW51ZF Battery

Bacteriocide in winemaking and food preservation

Small amounts of sulfur dioxide gas addition (or equivalent potassium metabisulfite addition) to fermented wine to produce traces of sulfurous acid (produced when SO2 reacts with water) and its sulfite salts in the mixture, has been called "the most powerful tool in winemaking."Sony VAIO VGN-FW51ZF/H Battery

The sulfites absorb oxygen to inhibitaerobic bacterial growth after the yeast-fermentation stage in winemaking, that otherwise would turn ethanol into acetic acid and thus cause the wine to "sour." Without this preservative step, indefinite refrigeration of the product before consumption is usually required. Sony VAIO VGN-FW52JB Battery

Similar methods go back into antiquity but modern historical mentions of the practice go to the fifteenth century. The practice is used by large industrial wine producers and small organic wine producers alike.

Sulfur dioxide and various sulfites have been used for their antioxidant antibacterial preservative properties in many other parts of the food industry also.Sony VAIO VGN-FW54FB Battery

The practice has declined since reports of a allergy-like reaction of some persons to sulfites in foods.

Protein and organic cofactors

Sulfur is an essential component of all living cells. It is the seventh or eighth most abundant element in the human body by weight, being about as common aspotassium, and a little more common than sodium or chlorine.Sony VAIO VGN-FW70DB Battery

A 70 kg human body contains about 140 grams of sulfur.

In plants and animals, the amino acids cysteine and methionine contain most of the sulfur. The element is thus present in all polypeptides, proteins, and enzymesthat contain these amino acids. Disulfide bonds (S-S bonds) formed between cysteine residues in peptide chains are very important in protein assembly and structure. Sony VAIO VGN-FW71DB/W Battery

These covalent bonds between peptide chains confer extra toughness and rigidity.For example, the high strength of feathers and hair is in part due to their high content of S-S bonds and their high content of cysteine and sulfur. Eggs are high in sulfur because large amounts of the element are necessary for feather formation, and the characteristic odor of rotting eggs is due to hydrogen sulfide.Sony VAIO VGN-FW72JGB Battery

The high disulfide bond content of hair and feathers contributes to their indigestibility and to their characteristic disagreeable odor when burned.

Homocysteine and taurine are other sulfur-containing acids that are similar in structure, but which are not coded by DNA, and are not part of the primary structureof proteins. Sony VAIO VGN-FW73JGB Battery

Many important cellular enzymes use prosthetic groups ending with -SH moieties to handle reactions involving acyl-containing biochemicals: two common examples from basic metabolism are coenzyme A and alpha-lipoic acid. Two of the 13 classical vitamins, biotin and thiamine contain sulfur, with the latter being named for its sulfur content. Sony VAIO VGN-FW74FB Battery

Sulfur plays an important part, as a carrier of reducing hydrogen and its electrons, for cellular repair of oxidation. Reducedglutathione, a sulfur-containing tripeptide, is a reducing agent through its sulfhydryl (-SH) moiety derived from cysteine.Sony VAIO VGN-FW81HS Battery

The thioredoxins, a class of small protein essential to all known life, using neighboring pairs of reduced cysteines to act as general protein reducing agents, to similar effect.

Methanogenesis, the route to most of the world's methane, is a multistep biochemical transformation of carbon dioxide. This conversion requires several organosulfur cofactors.Sony VAIO VGN-FW81NS Battery

These include coenzyme M, CH3SCH2CH2SO3–, the immediate precursor to methane.

Metalloproteins and inorganic cofactors

Inorganic sulfur forms a part of iron-sulfur clusters as well as many copper, nickel, and iron proteins. Most pervasive are the ferrodoxins, which serve as electron shuttles in cells. Sony VAIO VGN-FW81S Battery

In bacteria, the important nitrogenase enzymes contains an Fe-Mo-S cluster, is a catalyst that performs the important function of nitrogen fixation, converting atmospheric nitrogen to ammonia that can be used by microorganisms and plants to make proteins, DNA, RNA, alkaloids, and the other organic nitrogen compounds necessary for life.Sony VAIO VGN-FW82DS Battery

Sulfur metabolism

Sulfur may serve as energy (chemical food) source for bacteria that use hydrogen sulfide (H2S) in the place of water as the electron donor in a primitivephotosynthesis-like process in which oxygen is the electron receptor. Sony VAIO VGN-FW82JS Battery

The photosynthetic green sulfur bacteria and purple sulfur bacteria and some chemolithotrophsuse elemental oxygen to carry out such oxidization of hydrogen sulfide to produce elemental sulfur (S0), oxidation state = 0. Primitive bacteria which live around deep ocean volcanic vents oxidize hydrogen sulfide in this way with oxygen: Sony VAIO VGN-FW82XS Battery

see giant tube worm for an example of large organisms (via bacteria) making metabolic use of hydrogen sulfide as food to be oxidized.

The so-called sulfate-reducing bacteria, by contrast, "breathe sulfate" instead of oxygen. They use sulfur as the electron acceptor, and reduce various oxidized sulfur compounds back into sulfide, of

ten into hydrogen sulfide. Sony VAIO VGN-FW83DS Battery

They can grow on a number of other partially oxidized sulfur compounds (e. g. thiosulfates, thionates, polysulfides, sulfites). The hydrogen sulfide produced by these bacteria is responsible for some of the smell of intestinal gases (flatus) and decomposition products.Sony VAIO VGN-FW83JS Battery

Sulfur is absorbed by plants via the roots from soil as the sulfate and transported as a phosphate ester. Sulfate is reduced to sulfide via sulfite before it is incorporated into cysteine and other organosulfur compounds. Sony VAIO VGN-FW83XS Battery

SO42– ? SO32– ? H2S ? cysteine

Precautions

Elemental sulfur is non-toxic, as generally are the soluble sulfate salts, such as Epsom salts. Soluble sulfate salts are poorly absorbed and laxitive. However, when injected parenterally, they are freely filtered by the kidneys and elimimated with very little toxicity in multi-gram amounts.Sony VAIO VGN-FW90HS Battery

When sulfur burns in air it produces sulfur dioxide. In water, this gas produces sulfurous acid and sulfites which are antioxidants, inhibiting the growth of aerobic bacteria, and allowing it to be used as a food additive in small amounts. However, at high concentrations these acids harm the lungs, eyes or other tissues.Sony VAIO VGN-FW90NS Battery

In organisms without lungs such as insects or plants, it otherwise prevents respiration in high concentrations. Sulfur trioxide (made by catalysis from sulfur dioxide) and sulfuric acidare similarly highly corrosive, due to the strong acids that form on contact with water.Sony VAIO VGN-FW90S Battery

The burning of coal and/or petroleum by industry and power plants generates sulfur dioxide (SO2), which reacts with atmospheric water and oxygen to produce sulfuric acid (H2SO4) and sulfurous acid (H2SO3). These acids are components of acid rain, which lower the pH of soil and freshwater bodies, Sony VAIO VGN-FW91NS Battery

sometimes resulting in substantial damage to the environment and chemical weathering of statues and structures. Fuel standards increasingly require sulfur to be extracted from fossil fuels to prevent the formation of acid rain. This extracted sulfur is then refined and represents a large portion of sulfur production.Sony VAIO VGN-FW91S Battery

In coal fired power plants, the flue gases are sometimes purified. In more modern power plants that use synthesis gas the sulfur is extracted before the gas is burned.

Hydrogen sulfide is as toxic as hydrogen cyanide and kills by the same mechanism, although hydrogen sulfide is less likely to result in surprise poisonings from small inhaled amounts, due to its more disagreeable warning odor. Sony VAIO VGN-FW92DS Battery

However, although very pungent at first awareness to the human nose, hydrogen sulfide quickly deadens the sense of smell, so potential victims breathing larger and larger quantities of it may be unaware of its presence until severe symptoms occur (these can then quickly lead to death). Dissolved sulfide and hydrosulfide salts are also toxic by the same mechanism.Sony VAIO VGN-FW92JS Battery

The sulfur cycle are the collection of processes by which sulfur moves to and from minerals (including the waterways) and living systems. Such biogeochemical cycles are important in geology because they affect many minerals. Biogeochemical cycles are also important for life because sulfur is an essential element, being a constituent of many proteins and cofactors.Sony VAIO VGN-FW93DS Battery

Steps of the sulfur cycle are:

  • Mineralization of organic sulfur into inorganic forms, such as hydrogen sulfide (H2S), elemental sulfur, as well as sulfide mineralss.
  • Oxidation of hydrogen sulfide, sulfide, and elemental sulfur (S) to sulfate (SO42–).Sony VAIO VGN-FW93JS Battery
  • Reduction of sulfate to sulfide.
  • Incorporation sulfide into organic compounds (including metal-containing derivatives).

These are often termed as follows:

Assimilative sulfate reduction (see also sulfur assimilation) in which sulfate (SO42–) is reduced by plants, fungi and variousprokaryotes. The oxidation states of sulfur are +6 in sulfate and –2 in R–SH.Sony VAIO VGN-FW93XS Battery

Desulfurization in which organic molecules containing sulfur can be desulfurized, producing hydrogen sulfide gas (H2S, oxidation state = –2). An analogous process for organic nitrogen compounds is deamination.

Oxidation of hydrogen sulfide produces elemental sulfur (S8), oxidation state = 0. This reaction occurs in the photosynthetic green and purple sulfur bacteria and some chemolithotrophs. Often the elemental sulfur is stored as polysulfides.Sony VAIO VGN-FW94FS Battery

oxidation of elemental sulfur by sulfur oxidizers produces sulfate.

Dissimilative sulfur reduction in which elemental sulfur can be reduced to hydrogen sulfide.

Dissimilative sulfate reduction in which sulfate reducers generate hydrogen sulfide from sulfate.Sony VAIO VGN-FW94GS Battery

Sulfur sources and sinks

Sulfur is found in oxidation states ranging from +6 in SO4 to -2 in sulfides. Thus elemental sulfur can either give or receive electrons depending on its environment. Igneous rocks such as pyrite (FeS2) comprised the original pool of sulfur on earth. Sony VAIO VGN-FW94HS Battery

Owing to the sulfur cycle, the amount of mobile sulfur has been continuously increasing through volcanic activity as well as weathering of the crust in an oxygenated atmosphere.[1] Earth’s main sulfur sink is the oceans as SO2, where it is the major oxidizing agent. Sony VAIO VGN-G118CN Battery

When SO4 is assimilated by organisms, it is reduced and converted to organic sulfur, which is an essential component of proteins. However, the biosphere does not act as a major sink for sulfur, instead the majority of sulfur is found in seawater or sedimentary rocks especially pyrite rich shales and evaporite rocks (anhydrite andbaryte).Sony VAIO VGN-G118GN/B Battery

The amount of sulfate in the oceans is controlled by three major processes:

1. input from rivers

2. sulfate reduction and sulfide reoxidation on continental shelves and slopes

3. burial of anhydrite and pyrite in the oceanic crust.Sony VAIO VGN-G118GN/T Battery

There is no significant amount of sulfur held in the atmosphere with all of it coming from either sea spray or windblown sulfur rich dust,[4] neither of which is long lived in the atmosphere. In recent times the large annual input of sulfur from the burning of coal and other fossil fuels adds a substantial amount SO2 which acts as an air pollutant. Sony VAIO VGN-G118TN/B Battery

In the geologic past, igneous intrusions into coal measures have caused large scale burning of these measures, and consequential release of sulfur to the atmosphere. This has led to substantial disruption to the climate system, and is one of the proposed causes of the great dying.Sony VAIO VGN-G118TN/S Battery

Dimethylsulfide [(CH3)2S or DMS] is produced by the decomposition of dimethylsulfoniopropionate DMSP) from dying phytoplankton cells in the shallow levels of the ocean, and is the major biogenic gas emitted from the sea, where it is responsible for the distinctive “smell of the sea” along coastlines.Sony VAIO VGN-G11VN/T Battery

DMS is the largest natural source of sulfur gas, but still only has a residence time of about one day in the atmosphere and a majority of it is redeposited in the oceans rather than making it to land. However, it is a significant factor in the climate system, as it is involved in the formation of clouds.Sony VAIO VGN-G11VN/TC Battery

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