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47-704: The Ishbel Group is composed of carbonate rocks ( limestone and dolomite ) and sandstone , with minor chert and siltstone . Depositional conditions were similar to those of the Phosphoria Formation to the south in United States. Among the fossils that have been found in the Ishbel Group are corals , bryozoa , crinoids , and conodonts , as well as productid , chonetid and spiriferid brachiopods , omphalotrochid gastropods , and edestid elasmobranch fish. The Ishbel Group reaches

94-409: A buffer to stabilise it in the range 7.37–7.43: Exhaled CO 2 (g) depletes CO 2 (aq) , which in turn consumes H 2 CO 3 , causing the equilibrium of the first reaction to try to restore the level of carbonic acid by reacting bicarbonate with a hydrogen ion, an example of Le Châtelier's principle . The result is to make the blood more alkaline (raise pH). By the same principle, when

141-507: A Δ H of –2884.5  kJ / kg and a Δ S of 70.5 J/(mol·K): The rate of decomposition increases with rise in temperature, concentration, and pH . H 2 O 2 is unstable under alkaline conditions. Decomposition is catalysed by various redox-active ions or compounds, including most transition metals and their compounds (e.g. manganese dioxide ( MnO 2 ), silver , and platinum ). The redox properties of hydrogen peroxide depend on pH. In acidic solutions, H 2 O 2

188-796: A maximum thickness of up to about 425 metres (1400 ft). It is present in the front ranges of the Canadian Rockies as far north as the Peace River . The Ishbel Group is disnconformably overlain by the Spray River Group and unconformably overlies the Tunnel Mountain Formation and the Kananaskis Formation . It is partly equivalent to the Phosphoria Formation of Montana , Idaho , Wyoming , and Utah . Carbonate A carbonate

235-587: A model with fractional bonds and delocalized charges: Metal carbonates generally decompose on heating, liberating carbon dioxide leaving behind an oxide of the metal. This process is called calcination , after calx , the Latin name of quicklime or calcium oxide , CaO, which is obtained by roasting limestone in a lime kiln : As illustrated by its affinity for Ca , carbonate is a ligand for many metal cations. Transition metal carbonate and bicarbonate complexes feature metal ions covalently bonded to carbonate in

282-406: A variety of bonding modes. Lithium , sodium , potassium , rubidium , caesium , and ammonium carbonates are water-soluble salts, but carbonates of 2+ and 3+ ions are often poorly soluble in water. Of the insoluble metal carbonates, CaCO 3 is important because, in the form of scale , it accumulates in and impedes flow through pipes. Hard water is rich in this material, giving rise to

329-532: Is a salt of carbonic acid , ( H 2 CO 3 ), characterized by the presence of the carbonate ion , a polyatomic ion with the formula CO 2− 3 . The word "carbonate" may also refer to a carbonate ester , an organic compound containing the carbonate group O=C(−O−) 2 . The term is also used as a verb, to describe carbonation : the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverages – either by

376-399: Is a powerful oxidizer . Sulfite ( SO 2− 3 ) is oxidized to sulfate ( SO 2− 4 ). Under alkaline conditions, hydrogen peroxide is a reductant. When H 2 O 2 acts as a reducing agent, oxygen gas is also produced. For example, hydrogen peroxide will reduce sodium hypochlorite and potassium permanganate , which is a convenient method for preparing oxygen in

423-470: Is a useful "carrier" for H 2 O 2 in some reactions. Hydrogen peroxide ( H 2 O 2 ) is a nonplanar molecule with (twisted) C 2 symmetry ; this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy . Although the O−O bond is a single bond , the molecule has a relatively high rotational barrier of 386  cm (4.62  kJ / mol ) for rotation between enantiomers via

470-510: Is a weak acid, forming hydroperoxide or peroxide salts with many metals. It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, chromic acid ( CrO 3 and H 2 SO 4 ) forms a blue peroxide CrO(O 2 ) 2 . The aerobic oxidation of glucose in the presence of the enzyme glucose oxidase produces hydrogen peroxide. The conversion affords gluconolactone : Superoxide dismutases (SOD)s are enzymes that promote

517-456: Is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising significantly more readily, indicative of particularly strong hydrogen bonding. Diphosphane and hydrogen disulfide exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent lone pairs . Hydrogen peroxide

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564-444: Is attributed to the effects of hydrogen bonding , which is absent in the gaseous state. Crystals of H 2 O 2 are tetragonal with the space group D 4 or P 4 1 2 1 2. In aqueous solutions , hydrogen peroxide forms a eutectic mixture, exhibiting freezing-point depression down as low as –56 °C; pure water has a freezing point of 0 °C and pure hydrogen peroxide of –0.43 °C. The boiling point of

611-402: Is double bonded. These compounds are also known as organocarbonates or carbonate esters, and have the general formula R−O−C(=O)−O−R′ , or RR′CO 3 . Important organocarbonates include dimethyl carbonate , the cyclic compounds ethylene carbonate and propylene carbonate , and the phosgene replacement, triphosgene . Three reversible reactions control the pH balance of blood and act as

658-543: Is less than 0.014 μg/m , and in moderate photochemical smog it is 14 to 42 μg/m . The amount of hydrogen peroxide in biological systems can be assayed using a fluorometric assay . Alexander von Humboldt is sometimes said to have been the first to report the first synthetic peroxide, barium peroxide , in 1799 as a by-product of his attempts to decompose air, although this is disputed due to von Humboldt's ambiguous wording. Nineteen years later Louis Jacques Thénard recognized that this compound could be used for

705-479: Is oxidation of thioethers to form sulfoxides , such as conversion of thioanisole to methyl phenyl sulfoxide : Alkaline hydrogen peroxide is used for epoxidation of electron-deficient alkenes such as acrylic acid derivatives, and for the oxidation of alkylboranes to alcohols , the second step of hydroboration-oxidation . It is also the principal reagent in the Dakin oxidation process. Hydrogen peroxide

752-527: Is produced by various biological processes mediated by enzymes . Hydrogen peroxide has been detected in surface water, in groundwater, and in the atmosphere . It can also form when water is exposed to UV light. Sea water contains 0.5 to 14 μg/L of hydrogen peroxide, and freshwater contains 1 to 30 μg/L. Concentrations in air are about 0.4 to 4 μg/m , varying over several orders of magnitude depending in conditions such as season, altitude, daylight and water vapor content. In rural nighttime air it

799-441: Is related to the disparate lattice energies of solids composed of mono- vs dianions, as well as mono- vs dications. In aqueous solution , carbonate, bicarbonate, carbon dioxide, and carbonic acid participate in a dynamic equilibrium . In strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide , CO 2 (aq) ,

846-569: Is still used, was developed during the 1930s by the German chemical manufacturer IG Farben in Ludwigshafen . The increased demand and improvements in the synthesis methods resulted in the rise of the annual production of hydrogen peroxide from 35,000 tonnes in 1950, to over 100,000 tonnes in 1960, to 300,000 tonnes by 1970; by 1998 it reached 2.7 million tonnes. Early attempts failed to produce neat hydrogen peroxide. Anhydrous hydrogen peroxide

893-444: Is the main form, which, with water, H 2 O , is in equilibrium with carbonic acid – the equilibrium lies strongly towards carbon dioxide. Thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. In organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which

940-453: Is the simplest oxocarbon anion . It consists of one carbon atom surrounded by three oxygen atoms, in a trigonal planar arrangement, with D 3h molecular symmetry . It has a molecular mass of 60.01  g/mol and carries a total formal charge of −2. It is the conjugate base of the hydrogencarbonate (bicarbonate) ion, HCO − 3 , which is the conjugate base of H 2 CO 3 , carbonic acid . The Lewis structure of

987-410: Is used as an oxidizer , bleaching agent, and antiseptic , usually as a dilute solution (3%–6% by weight) in water for consumer use and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide ", decomposes explosively when heated and has been used as both a monopropellant and an oxidizer in rocketry . Hydrogen peroxide is a reactive oxygen species and

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1034-414: The trans configuration, and 2460 cm (29.4 kJ/mol) via the cis configuration. These barriers are proposed to be due to repulsion between the lone pairs of the adjacent oxygen atoms and dipolar effects between the two O–H bonds. For comparison, the rotational barrier for ethane is 1040 cm (12.4 kJ/mol). The approximately 100° dihedral angle between the two O–H bonds makes

1081-436: The disproportionation of superoxide into oxygen and hydrogen peroxide. Peroxisomes are organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids , branched chain fatty acids , D -amino acids , polyamines , and biosynthesis of plasmalogens and ether phospholipids , which are found in mammalian brains and lungs. They produce hydrogen peroxide in

1128-517: The 1820s, but early attempts of industrial production of peroxides failed. The first plant producing hydrogen peroxide was built in 1873 in Berlin . The discovery of the synthesis of hydrogen peroxide by electrolysis with sulfuric acid introduced the more efficient electrochemical method. It was first commercialized in 1908 in Weißenstein , Carinthia , Austria. The anthraquinone process , which

1175-512: The addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. In geology and mineralogy , the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, CO 2− 3 . Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock . The most common are calcite or calcium carbonate , CaCO 3 ,

1222-427: The anthraquinone. Most commercial processes achieve oxidation by bubbling compressed air through a solution of the anthrahydroquinone, with the hydrogen peroxide then extracted from the solution and the anthraquinone recycled back for successive cycles of hydrogenation and oxidation. The net reaction for the anthraquinone-catalyzed process is: The economics of the process depend heavily on effective recycling of

1269-459: The carbonate ion has two (long) single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen atom. This structure is incompatible with the observed symmetry of the ion, which implies that the three bonds are the same length and that the three oxygen atoms are equivalent. As in the case of the isoelectronic nitrate ion, the symmetry can be achieved by a resonance among three structures: This resonance can be summarized by

1316-453: The chief constituent of limestone (as well as the main component of mollusc shells and coral skeletons); dolomite , a calcium-magnesium carbonate CaMg(CO 3 ) 2 ; and siderite , or iron(II) carbonate , FeCO 3 , an important iron ore . Sodium carbonate ("soda" or "natron"), Na 2 CO 3 , and potassium carbonate ("potash"), K 2 CO 3 , have been used since antiquity for cleaning and preservation, as well as for

1363-443: The concentration increases above 68%) these grades are potentially far more hazardous and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers. Hydrogen peroxide has several structural analogues with H m X−XH n bonding arrangements (water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, S, N, P). Its melting point

1410-497: The extraction solvents, the hydrogenation catalyst and the expensive quinone . Hydrogen peroxide was once prepared industrially by hydrolysis of ammonium persulfate : [NH 4 ] 2 S 2 O 8 was itself obtained by the electrolysis of a solution of ammonium bisulfate ( [NH 4 ]HSO 4 ) in sulfuric acid . Small amounts are formed by electrolysis, photochemistry , electric arc , and related methods. A commercially viable route for hydrogen peroxide via

1457-445: The laboratory: The oxygen produced from hydrogen peroxide and sodium hypochlorite is in the singlet state . Hydrogen peroxide also reduces silver oxide to silver : Although usually a reductant, alkaline hydrogen peroxide converts Mn(II) to the dioxide: In a related reaction, potassium permanganate is reduced to Mn by acidic H 2 O 2 : Hydrogen peroxide is frequently used as an oxidizing agent . Illustrative

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1504-473: The long-term carbon cycle, due to the large number of marine organisms (especially coral) which are made of calcium carbonate. Increased solubility of carbonate through increased temperatures results in lower production of marine calcite and increased concentration of atmospheric carbon dioxide. This, in turn, increases Earth temperature. The amount of CO 2− 3 available is on a geological scale and substantial quantities may eventually be redissolved into

1551-435: The manufacture of glass . Carbonates are widely used in industry, such as in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes , and more. New applications of alkali metal carbonates include: thermal energy storage, catalysis and electrolyte both in fuel cell technology as well as in electrosynthesis of H 2 O 2 in aqueous media. The carbonate ion

1598-530: The middle of the 20th century at least half a dozen hypothetical isomeric variants of two main options seemed to be consistent with the available evidence. In 1934, the English mathematical physicist William Penney and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide that was very similar to the presently accepted one. In 1994, world production of H 2 O 2

1645-440: The molecule chiral . It is the smallest and simplest molecule to exhibit enantiomerism . It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of ribonucleic acids and therefore an origin of homochirality in an RNA world . The molecular structures of gaseous and crystalline H 2 O 2 are significantly different. This difference

1692-412: The need for infrastructural water softening . Acidification of carbonates generally liberates carbon dioxide : Thus, scale can be removed with acid. In solution the equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid is sensitive to pH, temperature, and pressure. Although di- and trivalent carbonates have low solubility, bicarbonate salts are far more soluble. This difference

1739-436: The observations. Small amounts of carbonate deposits have been found on Mars via spectral imaging and Martian meteorites also contain small amounts. Groundwater may have existed at Gusev and Meridiani Planum . Hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula H 2 O 2 . In its pure form, it is a very pale blue liquid that is slightly more viscous than water . It

1786-410: The pH is too high, the kidneys excrete bicarbonate ( HCO − 3 ) into urine as urea via the urea cycle (or Krebs–Henseleit ornithine cycle). By removing the bicarbonate, more H is generated from carbonic acid ( H 2 CO 3 ), which comes from CO 2 (g) produced by cellular respiration . Crucially, a similar buffer operates in the oceans. It is a major factor in climate change and

1833-522: The preparation of a previously unknown compound, which he described as eau oxygénée ("oxygenated water") — subsequently known as hydrogen peroxide. An improved version of Thénard's process used hydrochloric acid , followed by addition of sulfuric acid to precipitate the barium sulfate byproduct. This process was used from the end of the 19th century until the middle of the 20th century. The bleaching effect of peroxides and their salts on natural dyes had been known since Thénard's experiments in

1880-447: The reaction of hydrogen with oxygen favours production of water but can be stopped at the peroxide stage. One economic obstacle has been that direct processes give a dilute solution uneconomic for transportation. None of these has yet reached a point where it can be used for industrial-scale synthesis. Hydrogen peroxide is about 1000 times stronger as an acid than water. Hydrogen peroxide disproportionates to form water and oxygen with

1927-401: The reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by hydrogenation on a palladium catalyst . In the presence of oxygen , the anthrahydroquinone then undergoes autoxidation : the labile hydrogen atoms of the hydroxy groups transfer to the oxygen molecule, to give hydrogen peroxide and regenerating

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1974-467: The same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14 °C greater than that of pure water and 36.2 °C less than that of pure hydrogen peroxide. Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of

2021-412: The sea and released to the atmosphere, increasing CO 2 levels even more. It is generally thought that the presence of carbonates in rock is strong evidence for the presence of liquid water. Recent observations of the planetary nebula NGC 6302 show evidence for carbonates in space, where aqueous alteration similar to that on Earth is unlikely. Other minerals have been proposed which would fit

2068-1013: The simplest peroxide , a compound having an oxygen–oxygen single bond . It decomposes slowly into water and elemental oxygen when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in an opaque bottle. Hydrogen peroxide is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases . The boiling point of H 2 O 2 has been extrapolated as being 150.2 °C (302.4 °F), approximately 50 °C (90 °F) higher than water. In practice, hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure. Hydrogen peroxide forms stable adducts with urea ( hydrogen peroxide–urea ), sodium carbonate ( sodium percarbonate ) and other compounds. An acid-base adduct with triphenylphosphine oxide

2115-420: The volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as

2162-409: Was around 1.9 million tonnes and grew to 2.2 million in 2006, most of which was at a concentration of 70% or less. In that year, bulk 30% H 2 O 2 sold for around 0.54 USD / kg , equivalent to US$ 1.50/kg (US$ 0.68/ lb ) on a "100% basis". Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process , which was originally developed by BASF in 1939. It begins with

2209-473: Was first obtained by vacuum distillation . Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892, the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by freezing-point depression , which confirmed that its molecular formula is H 2 O 2 . H 2 O=O seemed to be just as possible as the modern structure, and as late as in

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