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Periodate
Periodate is an anion composed of iodine and oxygen. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7. Unlike other perhalogenates, such as perchlorate, it can exist in two forms: metaperiodate and orthoperiodate . In this regard it is comparable to the tellurate ion from the adjacent Group (periodic table), group. It can combine with a number of counter ions to form periodates, which may also be regarded as the salts of periodic acid. Periodates were discovered by Heinrich Gustav Magnus and C. F. Ammermüller; who first synthesised periodic acid in 1833. Synthesis Classically, periodate was most commonly produced in the form of sodium hydrogen periodate (). This is commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide. Or, similarly, from iodides by oxidation with bromine and sodium hydroxide: :\overset + Cl2 + 4 NaOH -> Na3H2IO6 + 2NaCl + H2O :Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Acid
Periodic acid ( ) is the highest oxoacid of iodine, in which the iodine exists in oxidation state +7. Like all periodates it can exist in two forms: orthoperiodic acid, with the chemical formula , and metaperiodic acid, which has the formula . Periodic acid was discovered by Heinrich Gustav Magnus and C. F. Ammermüller in 1833. Synthesis Modern industrial scale production involves the oxidation of a solution of sodium iodate under alkaline conditions, either electrochemically on a anode, or by treatment with chlorine: : (counter ions omitted for clarity) ''E''° = -1.6 V : Orthoperiodic acid can be dehydrated to give metaperiodic acid by heating to 100 °C under reduced pressure. : Further heating to around 150 °C gives iodine pentoxide () rather than the expected anhydride ''diiodine heptoxide'' (). Metaperiodic acid can also be prepared from various orthoperiodates by treatment with dilute nitric acid. Properties Orthoperiodic acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Acid
Periodic acid ( ) is the highest oxoacid of iodine, in which the iodine exists in oxidation state +7. Like all periodates it can exist in two forms: orthoperiodic acid, with the chemical formula , and metaperiodic acid, which has the formula . Periodic acid was discovered by Heinrich Gustav Magnus and C. F. Ammermüller in 1833. Synthesis Modern industrial scale production involves the oxidation of a solution of sodium iodate under alkaline conditions, either electrochemically on a anode, or by treatment with chlorine: : (counter ions omitted for clarity) ''E''° = -1.6 V : Orthoperiodic acid can be dehydrated to give metaperiodic acid by heating to 100 °C under reduced pressure. : Further heating to around 150 °C gives iodine pentoxide () rather than the expected anhydride ''diiodine heptoxide'' (). Metaperiodic acid can also be prepared from various orthoperiodates by treatment with dilute nitric acid. Properties Orthoperiodic acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodate
An iodate is the polyatomic anion with the formula . It is the most common form of iodine in nature, as it comprises the major iodine-containing ores. Iodate salts are often colorless. They are the salts of iodic acid. Structure Iodate is pyramidal in structure. The O–I–O angles range from 97° to 105°, somewhat smaller than the O–Cl–O angles in chlorate. Reactions Redox Iodate is one of several oxyanions of iodine, and has an oxidation number of +5. It participates in several redox reactions, such as the iodine clock reaction. Iodate show no tendency to disproportionate to periodate and iodide, in contrast to the situation for chlorate. Iodate is reduced by sulfite: :6HSO3- + 2IO3- -> 2I- + 6HSO4- Iodate oxidizes iodide: :5I- + IO3- + 3H2SO4 -> 3I2 + 3H2O + 3SO4^2- Similarly, chlorate oxidizes iodide to iodate: :I- + ClO3- -> Cl- + IO3- Iodate is also obtained by reducing a periodate with a sulfide. The byproduct of the reaction is a sulfoxide. Acid-base Iod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodine
Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek 'violet-coloured'. Iodine occurs in many oxidation states, including iodide (I−), iodate (), and the various periodate anions. It is the least abundant of the stable halogens, being the sixty-first most abundant element. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. The dominant producers of iodine today are Chile and Japan. Due to its high atomic number and ease of attachment to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perbromate
In chemistry, the perbromate ion is the anion having the chemical formula . It is an oxyanion of bromine, the conjugate base of perbromic acid, in which bromine has the oxidation state +7. Unlike its chlorine () and iodine () analogs, it is difficult to synthesize. It has tetrahedral molecular geometry. The term perbromate also refers to a compound that contains the anion or the functional group. The perbromate ion is a strong oxidizing agent. The reduction potential for the / Br− couple is +0.68 V at pH 14. This is comparable to selenite's reduction potential. Synthesis Attempted syntheses of perbromates were unsuccessful until 1968, when it was finally obtained by the beta decay of selenium-83 in a selenate salt: : → + β− Subsequently, it was successfully synthesized again by the electrolysis of , although only in low yield. Later, it was obtained by the oxidation of bromate with xenon difluoride. Once perbromates are obtained, perbromic acid can b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxyanion
An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound . The structures of condensed oxyanions can be rationalized in terms of AO''n'' polyhedral units with sharing of corners or edges between polyhedra. The oxyanions (specifically, phosphate and polyphosphate esters) adenosine monophosphate ( AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology. Monomeric oxyanions The formula of monomeric oxyanions, , is dictated by the oxidation state of the element A and its position in the periodic table. Elements of the first row are limited to a maximum coordination number of 4. However, none of the first row elements has a monomeric oxyanion with that coordination number. Instead, ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodide
An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. Structure and characteristics of inorganic iodides Iodide is one of the largest monatomic anions. It is assigned a radius of around 206 picometers. For comparison, the lighter halides are considerably smaller: bromide (196 pm), chloride (181 pm), and fluoride (133 pm). In part because of its size, iodide forms relatively weak bonds with most elements. Most iodide salts are soluble in water, but often less so than the related chlorides and bromides. Iodide, being large, is less hydrophilic compared to the smaller anions. One consequence of this is that sodium iodide is highly soluble in acetone, whereas sodium chloride is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Electrode Potential
In electrochemistry, standard electrode potential E^\ominus, or E^\ominus_, is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: ''"the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode"''. Background The basis for an electrochemical cell, such as the galvanic cell, is always a redox reaction which can be broken down into two half-reactions: oxidation at anode (loss of electron) and reduction at cathode (gain of electron). Electricity is produced due to the difference of electric potential between the individual potentials of the two metal electrodes with respect to the electrolyte. Although the overall potential of a cell can be measured, there is no simple way to accurately measure the electrode/electrolyte potentials in isolation. The electric potential also varies with temperature, concentration and pressur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Dioxide
Lead(IV) oxide is the inorganic compound with the formula PbO2. It is an oxide where lead is in an oxidation state of +4. It is a dark-brown solid which is insoluble in water. It exists in two crystalline forms. It has several important applications in electrochemistry, in particular as the positive plate of lead acid batteries. Properties Physical Lead dioxide has two major polymorphs, alpha and beta, which occur naturally as rare minerals scrutinyite and plattnerite, respectively. Whereas the beta form had been identified in 1845, α-PbO2 was first identified in 1946 and found as a naturally occurring mineral 1988. The alpha form has orthorhombic symmetry, space group Pbcn (No. 60), Pearson symbol ''oP''12, lattice constants ''a'' = 0.497 nm, ''b'' = 0.596 nm, ''c'' = 0.544 nm, ''Z'' = 4 (four formula units per unit cell). The lead atoms are six-coordinate. The symmetry of the beta form is tetragonal, space group P42/mnm (No. 136), Pearson symbol ''tP''6, la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Electrode Potential
In electrochemistry, standard electrode potential E^\ominus, or E^\ominus_, is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: ''"the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode"''. Background The basis for an electrochemical cell, such as the galvanic cell, is always a redox reaction which can be broken down into two half-reactions: oxidation at anode (loss of electron) and reduction at cathode (gain of electron). Electricity is produced due to the difference of electric potential between the individual potentials of the two metal electrodes with respect to the electrolyte. Although the overall potential of a cell can be measured, there is no simple way to accurately measure the electrode/electrolyte potentials in isolation. The electric potential also varies with temperature, concentration and pressur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acid Dissociation Constant
In chemistry, an acid dissociation constant (also known as acidity constant, or acid-ionization constant; denoted ) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction :HA A^- + H^+ known as dissociation in the context of acid–base reactions. The chemical species HA is an acid that dissociates into , the conjugate base of the acid and a hydrogen ion, . The system is said to be in equilibrium when the concentrations of its components will not change over time, because both forward and backward reactions are occurring at the same rate. The dissociation constant is defined by :K_\text = \mathrm, or :\mathrmK_\ce = - \log_ K_\text = \log_\frac where quantities in square brackets represent the concentrations of the species at equilibrium. Theoretical background The acid dissociation constant for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the p''K''a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitric Acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution contains more than 86% , it is referred to as ''fuming nitric acid''. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%. Nitric acid is the primary reagent used for nitration – the addition of a nitro group, typically to an organic molecule. While some resulting nitro compounds are shock- and thermally-sensitive explosives, a few are stable enough to be used in munitions and demolition, while others are still more stable and used as pigments in inks and dyes. Nitric acid is also commonly used as a strong oxidizing age ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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