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57-446: Palladium(II) sulfide is formed when hydrogen sulfide is passed through an aqueous solution containing palladium in the +2 oxidation state : Berzelius reacted palladium directly with sulfur to produce palladium(II) sulfide in 1813: The crystal structure of PdS contains approximately square planar palladium centres and tetrahedral sulfur centres. If palladium(II) sulfide is heated with an excess of sulfur, palladium disulfide

114-472: A T c of 473 K (200 °C) at 250 GPa. It is also possible that if the bipolaron explanation is correct, a normally semiconducting material can transition under some conditions into a superconductor if a critical level of alternating spin coupling in a single plane within the lattice is exceeded; this may have been documented in very early experiments from 1986. The best analogy here would be anisotropic magnetoresistance , but in this case

171-416: A carbonaceous sulfur hydride at 267 GPa, triggered into crystallisation via green laser. This was retracted in 2022 after flaws in their statistical methods were identified and led to questioning of other data. In 2023 he reported superconductivity at 294 K and 1 GPa in nitrogen-doped lutetium hydride , in a paper widely met with skepticism about its methods and data. Later in 2023 he

228-513: A characteristic foul odor of rotten eggs . Swedish chemist Carl Wilhelm Scheele is credited with having discovered the chemical composition of purified hydrogen sulfide in 1777. Hydrogen sulfide is toxic to humans and most other animals by inhibiting cellular respiration in a manner similar to hydrogen cyanide . When it is inhaled or its salts are ingested in high amounts, damage to organs occurs rapidly with symptoms ranging from breathing difficulties to convulsions and death. Despite this,

285-472: A few weeks. Long-term, low-level exposure may result in fatigue , loss of appetite, headaches , irritability, poor memory, and dizziness . Chronic exposure to low level H 2 S (around 2 ppm ) has been implicated in increased miscarriage and reproductive health issues among Russian and Finnish wood pulp workers, but the reports have not (as of 1995) been replicated. Short-term, high-level exposure can induce immediate collapse, with loss of breathing and

342-857: A high probability of death. If death does not occur, high exposure to hydrogen sulfide can lead to cortical pseudolaminar necrosis , degeneration of the basal ganglia and cerebral edema . Although respiratory paralysis may be immediate, it can also be delayed up to 72 hours. Inhalation of H 2 S resulted in about 7 workplace deaths per year in the U.S. (2011–2017 data), second only to carbon monoxide (17 deaths per year) for workplace chemical inhalation deaths. Treatment involves immediate inhalation of amyl nitrite , injections of sodium nitrite , or administration of 4-dimethylaminophenol in combination with inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm , and in some cases hyperbaric oxygen therapy (HBOT). HBOT has clinical and anecdotal support. Hydrogen sulfide

399-472: A metallic conductor of electricity. When cooled below a critical temperature this high-pressure phase exhibits superconductivity . The critical temperature increases with pressure, ranging from 23 K at 100 GPa to 150 K at 200 GPa. If hydrogen sulfide is pressurized at higher temperatures, then cooled, the critical temperature reaches 203 K (−70 °C), the highest accepted superconducting critical temperature as of 2015. By substituting

456-424: A paper in a journal, and submitted a patent application. The reported observations were received with skepticism by experts due to the lack of clear signatures of superconductivity. The story was widely discussed on social media, leading to a large number of attempted replications, none of which had more than qualified success. By mid-August, a series of papers from major labs provided significant evidence that LK-99

513-497: A phenomenon that he explained as room-temperature superconductivity within a phase formed on the surface of oxygen-doped type IIa diamonds in a 10  mbar vacuum . In 2003, a group of researchers published results on high-temperature superconductivity in palladium hydride (PdH x : x > 1 ) and an explanation in 2004. In 2007, the same group published results suggesting a superconducting transition temperature of 260 K, with transition temperature increasing as

570-806: A possible superconducting phase at 260 K (−13 °C) in lanthanum decahydride ( La H 10 ) at elevated (200  GPa ) pressure. In 2019, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride, whose transition temperature is approximately 250 K (−23 °C). In 1993 and 1997, Michel Laguës and his team published evidence of room temperature superconductivity observed on MBE deposited ultrathin nanostructures of BiSrCaCuO. These compounds exhibit extremely low resistivities orders of magnitude below that of copper, strongly non-linear I(V) characteristics and hysteretic I(V) behavior. In 2000, while extracting electrons from diamond during ion implantation work, Johan Prins claimed to have observed

627-400: A result of the action of sulfate-reducing bacteria . Hydrogen sulfide is produced by the human body in small quantities through bacterial breakdown in the intestinal tract of proteins containing sulfur; it therefore contributes to the characteristic odor of flatulence. It is also produced in the mouth ( halitosis ). A portion of global H 2 S emissions are due to human activity. By far

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684-510: A small part of sulfur with phosphorus and using even higher pressures, it has been predicted that it may be possible to raise the critical temperature to above 0 °C (273 K) and achieve room-temperature superconductivity . Hydrogen sulfide decomposes without a presence of a catalyst under atmospheric pressure around 1200 °C into hydrogen and sulfur. Hydrogen sulfide reacts with metal ions to form metal sulfides, which are insoluble, often dark colored solids. Lead(II) acetate paper

741-704: A subject of discussion since the early 1950s. Since the discovery of high-temperature superconductors ("high" being temperatures above 77 K (−196.2 °C; −321.1 °F), the boiling point of liquid nitrogen ), several materials have been claimed, although not confirmed, to be room-temperature superconductors. In 2014, an article published in Nature suggested that some materials, notably YBCO ( yttrium barium copper oxide ), could be made to briefly superconduct at room temperature using infrared laser pulses. In 2015, an article published in Nature by researchers of

798-464: A waste product. Water heaters can aid the conversion of sulfate in water to hydrogen sulfide gas. This is due to providing a warm environment sustainable for sulfur bacteria and maintaining the reaction which interacts between sulfate in the water and the water heater anode, which is usually made from magnesium metal. H 2 S in the body acts as a gaseous signaling molecule with implications for health and in diseases. Hydrogen sulfide

855-485: Is stinkdamp . Hydrogen sulfide is a highly toxic and flammable gas ( flammable range : 4.3–46%). It can poison several systems in the body, although the nervous system is most affected. The toxicity of H 2 S is comparable with that of carbon monoxide . It binds with iron in the mitochondrial cytochrome enzymes , thus preventing cellular respiration . Its toxic properties were described in detail in 1843 by Justus von Liebig . Even before hydrogen sulfide

912-471: Is a hypothetical material capable of displaying superconductivity above 0 °C (273 K; 32 °F), operating temperatures which are commonly encountered in everyday settings. As of 2023, the material with the highest accepted superconducting temperature was highly pressurized lanthanum decahydride , whose transition temperature is approximately 250 K (−23 °C) at 200 GPa. At standard atmospheric pressure , cuprates currently hold

969-433: Is also known to increase the levels of glutathione, which acts to reduce or disrupt ROS levels in cells. The field of H 2 S biology has advanced from environmental toxicology to investigate the roles of endogenously produced H 2 S in physiological conditions and in various pathophysiological states. H 2 S has been implicated in cancer and Down syndrome and vascular disease. It inhibits Complex IV of

1026-506: Is also produced by heating sulfur with solid organic compounds and by reducing sulfurated organic compounds with hydrogen. It can also be produced by mixing ammonium thiocyanate to concentrated sulphuric acid and adding water to it. Hydrogen sulfide can be generated in cells via enzymatic or non-enzymatic pathways. Three enzymes catalyze formation of H 2 S : cystathionine γ-lyase (CSE), cystathionine β-synthetase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST). CBS and CSE are

1083-622: Is composed of silver particles embedded in a gold matrix. Due to similar noise patterns of supposedly independent plots and the publication's lack of peer review , the results have been called into question. Although the researchers repeated their findings in a later paper in 2019, this claim is yet to be verified and confirmed. Since 2016, a team led by Ranga P. Dias has produced a number of retracted or challenged papers in this field. In 2016 they claimed observation of solid metallic hydrogen in 2016. In October 2020, they reported room-temperature superconductivity at 288 K (at 15 °C) in

1140-521: Is formed: A variety of other compounds in the Pd-S system have been reported, including Pd 4 S, Pd 2.8 S, Pd 2.2 S and PdS 2 . The mineral Braggite has the composition (Pt, Pd, Ni)S and is isomorphous with PdS. Hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula H 2 S . It is a colorless chalcogen-hydride gas , and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having

1197-423: Is generally criticised among collectors. Hydrogen sulfide is most commonly obtained by its separation from sour gas , which is natural gas with a high content of H 2 S . It can also be produced by treating hydrogen with molten elemental sulfur at about 450 °C. Hydrocarbons can serve as a source of hydrogen in this process. The very favorable thermodynamics for the hydrogenation of sulfur implies that

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1254-420: Is harmless. Hence, low levels of hydrogen sulfide may be tolerated indefinitely. Exposure to lower concentrations can result in eye irritation, a sore throat and cough , nausea, shortness of breath, and fluid in the lungs . These effects are believed to be due to hydrogen sulfide combining with alkali present in moist surface tissues to form sodium sulfide , a caustic . These symptoms usually subside in

1311-409: Is involved in vasodilation in animals, as well as in increasing seed germination and stress responses in plants. Hydrogen sulfide signaling is moderated by reactive oxygen species (ROS) and reactive nitrogen species (RNS). H 2 S has been shown to interact with NO resulting in several different cellular effects, as well as the formation of another signal called nitrosothiol. Hydrogen sulfide

1368-535: Is produced when the silver on the surface of the coin reacts with atmospheric hydrogen sulfide. Coins that have been subject to toning by hydrogen sulfide and other sulfur-containing compounds may have the toning add to the numismatic value of a coin based on aesthetics, as the toning may produce thin-film interference , resulting in the coin taking on an attractive coloration. Coins can also be intentionally treated with hydrogen sulfide to induce toning, though artificial toning can be distinguished from natural toning, and

1425-499: Is slightly denser than air. A mixture of H 2 S and air can be explosive. In general, hydrogen sulfide acts as a reducing agent , as indicated by its ability to reduce sulfur dioxide in the Claus process . Hydrogen sulfide burns in oxygen with a blue flame to form sulfur dioxide ( SO 2 ) and water : If an excess of oxygen is present, sulfur trioxide ( SO 3 ) is formed, which quickly hydrates to sulfuric acid : It

1482-459: Is slightly soluble in water and acts as a weak acid ( p K a  = 6.9 in 0.01–0.1 mol/litre solutions at 18 °C), giving the hydrosulfide ion HS . Hydrogen sulfide and its solutions are colorless. When exposed to air, it slowly oxidizes to form elemental sulfur, which is not soluble in water. The sulfide anion S is not formed in aqueous solution. At pressures above 90 GPa ( gigapascal ), hydrogen sulfide becomes

1539-529: Is typically removed by amine gas treating technologies. In such processes, the hydrogen sulfide is first converted to an ammonium salt, whereas the natural gas is unaffected. The bisulfide anion is subsequently regenerated by heating of the amine sulfide solution. Hydrogen sulfide generated in this process is typically converted to elemental sulfur using the Claus Process . The underground mine gas term for foul-smelling hydrogen sulfide-rich gas mixtures

1596-405: Is used to detect hydrogen sulfide because it readily converts to lead(II) sulfide , which is black. Treating metal sulfides with strong acid or electrolysis often liberates hydrogen sulfide. Hydrogen sulfide is also responsible for tarnishing on various metals including copper and silver ; the chemical responsible for black toning found on silver coins is silver sulfide ( Ag 2 S ), which

1653-510: Is working with doughnut shapes rather than planar at the diamond culette tips. In 1964, William A. Little proposed the possibility of high-temperature superconductivity in organic polymers . In 2004, Ashcroft returned to his idea and suggested that hydrogen-rich compounds can become metallic and superconducting at lower pressures than hydrogen. More specifically, he proposed a novel way to pre-compress hydrogen chemically by examining IVa hydrides . In 2014–2015, conventional superconductivity

1710-645: The Bakken formation crude, possibly due to oil field practices, and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements". Besides living near gas and oil drilling operations, ordinary citizens can be exposed to hydrogen sulfide by being near waste water treatment facilities, landfills and farms with manure storage. Exposure occurs through breathing contaminated air or drinking contaminated water. In municipal waste landfill sites ,

1767-578: The Otto Hahn Institute suggested that under certain conditions such as extreme pressure H 2 S transitioned to a superconductive form H 3 S at 150 GPa (around 1.5 million times atmospheric pressure) in a diamond anvil cell . The critical temperature is 203 K (−70 °C) which would be the highest T c ever recorded and their research suggests that other hydrogen compounds could superconduct at up to 260 K (−13 °C). Also in 2018, researchers noted

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1824-488: The human body produces small amounts of this sulfide and its mineral salts, and uses it as a signalling molecule . Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers; this process is commonly known as anaerobic digestion , which is done by sulfate-reducing microorganisms . It also occurs in volcanic gases , natural gas deposits, and sometimes in well-drawn water. Hydrogen sulfide

1881-639: The 2015 results in H 2 S as a plausible explanation for transient resistance drops or "USO" noticed in the 1990s by Chu et al. during research after the discovery of YBCO . It has been predicted that Sc H 12 ( scandium dodecahydride ) would exhibit superconductivity at room temperature – T c between 333 K (60 °C) and 398 K (125 °C) – under a pressure expected not to exceed 100 GPa. Some research efforts are currently moving towards ternary superhydrides , where it has been predicted that Li 2 MgH 16 ( dilithium magnesium hexadecahydride ) would have

1938-514: The Kraft process), tanneries and sewerage . H 2 S arises from virtually anywhere where elemental sulfur comes in contact with organic material, especially at high temperatures. Depending on environmental conditions, it is responsible for deterioration of material through the action of some sulfur oxidizing microorganisms. It is called biogenic sulfide corrosion . In 2011 it was reported that increased concentrations of H 2 S were observed in

1995-546: The authors have not been able to demonstrate the occurrence of a clear Meissner phase and the vanishing of the material's resistance. In 2018, Dev Kumar Thapa and Anshu Pandey from the Solid State and Structural Chemistry Unit of the Indian Institute of Science , Bangalore claimed the observation of superconductivity at ambient pressure and room temperature in films and pellets of a nanostructured material that

2052-540: The burial of organic material rapidly leads to the production of anaerobic digestion within the waste mass and, with the humid atmosphere and relatively high temperature that accompanies biodegradation , biogas is produced as soon as the air within the waste mass has been reduced. If there is a source of sulfate bearing material, such as plasterboard or natural gypsum (calcium sulfate dihydrate), under anaerobic conditions sulfate reducing bacteria converts this to hydrogen sulfide. These bacteria cannot survive in air but

2109-422: The conduction electrons and the lattice-vibration phonons . A team at Harvard University has claimed to make metallic hydrogen and reports a pressure of 495 GPa. Though the exact critical temperature has not yet been determined, weak signs of a possible Meissner effect and changes in magnetic susceptibility at 250 K may have appeared in early magnetometer tests on an original now-lost sample. A French team

2166-590: The corresponding metal sulfides. Oxidic ores are sometimes treated with hydrogen sulfide to give the corresponding metal sulfides which are more readily purified by flotation . Metal parts are sometimes passivated with hydrogen sulfide. Catalysts used in hydrodesulfurization are routinely activated with hydrogen sulfide. Hydrogen sulfide was a reagent in the qualitative inorganic analysis of metal ions. In these analyses, heavy metal (and nonmetal ) ions (e.g., Pb(II), Cu(II), Hg(II), As(III)) are precipitated from solution upon exposure to H 2 S . The components of

2223-519: The cysteine catabolic pathway. Dietary amino acids, such as methionine and cysteine serve as the primary substrates for the transulfuration pathways and in the production of hydrogen sulfide. Hydrogen sulfide can also be derived from proteins such as ferredoxins and Rieske proteins . Sulfate-reducing (resp. sulfur-reducing ) bacteria generate usable energy under low-oxygen conditions by using sulfates (resp. elemental sulfur) to oxidize organic compounds or hydrogen; this produces hydrogen sulfide as

2280-462: The dehydrogenation (or cracking ) of hydrogen sulfide would require very high temperatures. A standard lab preparation is to treat ferrous sulfide with a strong acid in a Kipp generator : For use in qualitative inorganic analysis , thioacetamide is used to generate H 2 S : Many metal and nonmetal sulfides, e.g. aluminium sulfide , phosphorus pentasulfide , silicon disulfide liberate hydrogen sulfide upon exposure to water: This gas

2337-468: The density of hydrogen inside the palladium lattice increases. This has not been corroborated by other groups. In March 2021, an announcement reported superconductivity in a layered yttrium-palladium-hydron material at 262 K and a pressure of 187 GPa. Palladium may act as a hydrogen migration catalyst in the material. On 31 December 2023, "Global Room-Temperature Superconductivity in Graphite"

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2394-409: The largest industrial source of H 2 S is petroleum refineries : The hydrodesulfurization process liberates sulfur from petroleum by the action of hydrogen. The resulting H 2 S is converted to elemental sulfur by partial combustion via the Claus process , which is a major source of elemental sulfur. Other anthropogenic sources of hydrogen sulfide include coke ovens, paper mills (using

2451-420: The main proponents of H 2 S biogenesis, which follows the trans-sulfuration pathway. These enzymes have been identified in a breadth of biological cells and tissues, and their activity is induced by a number of disease states. These enzymes are characterized by the transfer of a sulfur atom from methionine to serine to form a cysteine molecule. 3-MST also contributes to hydrogen sulfide production by way of

2508-579: The mitochondrial electron transport chain, which effectively reduces ATP generation and biochemical activity within cells. Hydrogen sulfide is mainly consumed as a precursor to elemental sulfur. This conversion, called the Claus process , involves partial oxidation to sulfur dioxide. The latter reacts with hydrogen sulfide to give elemental sulfur. The conversion is catalyzed by alumina. Many fundamental organosulfur compounds are produced using hydrogen sulfide. These include methanethiol , ethanethiol , and thioglycolic acid . Hydrosulfides can be used in

2565-474: The moist, warm, anaerobic conditions of buried waste that contains a high source of carbon – in inert landfills, paper and glue used in the fabrication of products such as plasterboard can provide a rich source of carbon – is an excellent environment for the formation of hydrogen sulfide. In industrial anaerobic digestion processes, such as waste water treatment or the digestion of organic waste from agriculture , hydrogen sulfide can be formed from

2622-471: The outcome is a drop to zero rather than a decrease within a very narrow temperature range for the compounds tested similar to " re-entrant superconductivity ". In 2018, support was found for electrons having anomalous 3/2 spin states in YPtBi. Though YPtBi is a relatively low temperature superconductor, this does suggest another approach to creating superconductors. "Quantum bipolarons" could describe how

2679-480: The production of thiophenol . Upon combining with alkali metal bases, hydrogen sulfide converts to alkali hydrosulfides such as sodium hydrosulfide and sodium sulfide : Sodium sulfides are used in the paper making industry. Specifically, salts of SH break bonds between lignin and cellulose components of pulp in the Kraft process . As indicated above, many metal ions react with hydrogen sulfide to give

2736-435: The reduction of sulfate and the degradation of amino acids and proteins within organic compounds. Sulfates are relatively non-inhibitory to methane forming bacteria but can be reduced to H 2 S by sulfate reducing bacteria , of which there are several genera. A number of processes have been designed to remove hydrogen sulfide from drinking water . Hydrogen sulfide is commonly found in raw natural gas and biogas. It

2793-729: The resulting solid are then identified by their reactivity. Hydrogen sulfide is used to separate deuterium oxide, or heavy water , from normal water via the Girdler sulfide process . A suspended animation-like state has been induced in rodents with the use of hydrogen sulfide, resulting in hypothermia with a concomitant reduction in metabolic rate. Oxygen demand was also reduced, thereby protecting against hypoxia . In addition, hydrogen sulfide has been shown to reduce inflammation in various situations. Volcanoes and some hot springs (as well as cold springs ) emit some H 2 S . Hydrogen sulfide can be present naturally in well water, often as

2850-638: The sense of smell, creating temporary anosmia , so victims may be unaware of its presence until it is too late. Safe handling procedures are provided by its safety data sheet (SDS) . Since hydrogen sulfide occurs naturally in the body, the environment, and the gut, enzymes exist to metabolize it. At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm. Metabolism causes oxidation to sulfate, which

2907-403: The temperature record, manifesting superconductivity at temperatures as high as 138 K (−135 °C). Over time, researchers have consistently encountered superconductivity at temperatures previously considered unexpected or impossible, challenging the notion that achieving superconductivity at room temperature was infeasible. The concept of "near-room temperature" transient effects has been

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2964-462: Was discovered, Italian physician Bernardino Ramazzini hypothesized in his 1713 book De Morbis Artificum Diatriba that occupational diseases of sewer-workers and blackening of coins in their clothes may be caused by an unknown invisible volatile acid (moreover, in late 18th century toxic gas emanation from Paris sewers became a problem for the citizens and authorities). Although very pungent at first (it smells like rotten eggs ), it quickly deadens

3021-502: Was found to have plagiarized parts of his dissertation from someone else's thesis, and to have fabricated data in a paper on manganese disulfide , which was retracted. The lutetium hydride paper was also retracted. The first attempts to replicate those results failed. On July 23, 2023, a Korean team claimed that Cu-doped lead apatite, which they named LK-99 , was superconducting up to 370 K, though they had not observed this fully. They posted two preprints to arXiv , published

3078-499: Was not a superconductor, finding resistivity much higher than copper, and explaining observed effects such as magnetic response and resistance drops in terms of impurities and ferromagnetism in the material. Theoretical work by British physicist Neil Ashcroft predicted that solid metallic hydrogen at extremely high pressure (~500  GPa ) should become superconducting at approximately room temperature, due to its extremely high speed of sound and expected strong coupling between

3135-421: Was observed in a sulfur hydride system ( H 2 S or H 3 S ) at 190 K to 203 K at pressures of up to 200 GPa. In 2016, research suggested a link between palladium hydride containing small impurities of sulfur nanoparticles as a plausible explanation for the anomalous transient resistance drops seen during some experiments, and hydrogen absorption by cuprates was suggested in light of

3192-426: Was published in the journal Advanced Quantum Technologies , claiming to demonstrate superconductivity at room temperature and ambient pressure in highly oriented pyrolytic graphite with dense arrays of nearly parallel line defects. In 2012, an Advanced Materials article claimed superconducting behavior of graphite powder after treatment with pure water at temperatures as high as 300 K and above. So far,

3249-509: Was used by the British Army as a chemical weapon during World War I . It was not considered to be an ideal war gas, partially due to its flammability and because the distinctive smell could be detected from even a small leak, alerting the enemy to the presence of the gas. It was nevertheless used on two occasions in 1916 when other gases were in short supply. Room-temperature superconductor A room-temperature superconductor

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