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Superoxides
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen , which occurs widely in nature. Molecular oxygen (dioxygen) is a diradical containing two unpaired electrons, and superoxide results from the addition of an electron which fills one of the two degenerate molecular orbitals, leaving a charged ionic species with a single unpaired electron and a net negative charge of −1. Both dioxygen and the superoxide anion are free radicals that exhibit paramagnetism. Superoxide was historically also known as "hyperoxide". Salts Superoxide forms salts with alkali metals and alkaline earth metals. The salts caesium superoxide (), rubidium superoxide (), potassium superoxide (), and sodium superoxide () are prepared by the reaction of with the respective alka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caesium Superoxide
Caesium superoxide is the superoxide of caesium. It is an orange solid. Preparation Burning caesium in excess oxygen will produce caesium superoxide. : Properties Caesium superoxide's crystal structure is same as calcium carbide. It contains direct oxygen-oxygen bonding. It reacts with water to form hydrogen peroxide and caesium hydroxide. : The standard enthalpy of formation ΔHf0 of caesium superoxide is −295 kJ/mol. Caesium superoxide reacts with ozone to form caesium ozonide Caesium ozonide (CsO3) is an oxygen-rich compound of caesium. It is an ozonide, meaning it contains the ozonide anion (O3−). It can be formed by reacting ozone with caesium superoxide: :CsO2 + O3 -> CsO3 + O2 The compound will react strongly .... : References Caesium compounds Superoxides {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubidium Superoxide
Rubidium superoxide or Rubidium hyperoxide is a compound with the formula . In terms of oxidation states, the negatively charged superoxide and positively charged rubidium give it a structural formula of (Rb+)(O2−). Chemistry It can be created by slowly exposing elemental rubidium to oxygen gas: :Rb(s) + O2(g) → RbO2(s) Like other alkali metal hyperoxides, crystals can also be grown in liquid ammonia. Between 280 and 360 °C, Rubidium superoxide will decompose, leaving not rubidium sesquioxide (Rb2O3), but rather rubidium peroxide (Rb2O2). :RbO2 (s) → 1/2 R2O2(s) + 1/2 O2(g) An even more oxygen rich compound, that of rubidium ozonide (RbO3) can be created using RbO2. Properties Roughly speaking, RbO2 has a crystal structure similar to tetragonal calcium carbide, but is rather distorted due to the Jahn–Teller effect, which makes the crystal structure less symmetrical. RbO2 is stable in dry air, but is extremely hygroscopic. The compound has been studied as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroperoxyl
The hydroperoxyl radical, also known as the hydrogen superoxide, is the protonated form of superoxide with the chemical formula HO2. This species plays an important role in the atmosphere and as a reactive oxygen species in cell biology. Structure and reactions The molecule has a bent structure. The superoxide anion, , and the hydroperoxyl radical exist in equilibrium in aqueous solution: : + H2O HO2 + OH− The p''K''a of HO2 is 4.88. Therefore, about 0.3% of any superoxide present in the cytosol of a typical cell is in the protonated form. It oxidizes nitric oxide to nitrogen dioxide: :NO + HO2 → NO2 + HO Reactive oxygen species in biology Together with its conjugate base superoxide, hydroperoxyl is an important reactive oxygen species. Unlike , which has reducing properties, HO2 can act as an oxidant in a number of biologically important reactions, such as the abstraction of hydrogen atoms from tocopherol and polyunstaturated fatty acids in the lipid bilaye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroperoxyl
The hydroperoxyl radical, also known as the hydrogen superoxide, is the protonated form of superoxide with the chemical formula HO2. This species plays an important role in the atmosphere and as a reactive oxygen species in cell biology. Structure and reactions The molecule has a bent structure. The superoxide anion, , and the hydroperoxyl radical exist in equilibrium in aqueous solution: : + H2O HO2 + OH− The p''K''a of HO2 is 4.88. Therefore, about 0.3% of any superoxide present in the cytosol of a typical cell is in the protonated form. It oxidizes nitric oxide to nitrogen dioxide: :NO + HO2 → NO2 + HO Reactive oxygen species in biology Together with its conjugate base superoxide, hydroperoxyl is an important reactive oxygen species. Unlike , which has reducing properties, HO2 can act as an oxidant in a number of biologically important reactions, such as the abstraction of hydrogen atoms from tocopherol and polyunstaturated fatty acids in the lipid bilaye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Superoxide
Sodium superoxide is the inorganic compound with the formula Na O2. This yellow-orange solid is a salt of the superoxide anion. It is an intermediate in the oxidation of sodium by oxygen. Preparation NaO2 is prepared by treating sodium peroxide with oxygen at high pressures: :Na2O2 + O2 → 2 NaO2 It can also be prepared by careful oxygenation of a solution of sodium in ammonia: :Na(in NH3) + O2 → NaO2 It is also produced, along with sodium peroxide, when sodium is stored under inappropriate conditions (e.g. in dirty or partially halogenated solvents). Properties The product is paramagnetic, as expected for a salt of the anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve .... It hydrolyses readily to give a mixture of sodium hydroxide, oxygen and hydrogen peroxide.Sas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Superoxide
Potassium superoxide is an inorganic compound with the formula KO2. It is a yellow paramagnetic solid that decomposes in moist air. It is a rare example of a stable salt of the superoxide anion. It is used as a scrubber, dehumidifier, and generator in rebreathers, spacecraft, submarines, and spacesuits. Production and reactions Potassium superoxide is produced by burning molten potassium in an atmosphere of excess oxygen. :K + → The salt consists of and ions, linked by ionic bonding. The O−O distance is 1.28 Å. Reactivity Potassium superoxide is a source of superoxide, which is a reductant and a nucleophile, depending on its reaction partner. Upon contact with water, it undergoes disproportionation to potassium hydroxide, oxygen, and hydrogen peroxide: :2 + → 2 KOH + : + → KOH + + It reacts with carbon dioxide, releasing oxygen: :2 + → K2CO3 + :2 + 2 + H2O → 2 KHCO3 + Potassium superoxide finds only niche uses as a laboratory reag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Sulfoxide
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is miscible in a wide range of organic solvents as well as water. It has a relatively high boiling point. DMSO has the unusual property that many individuals perceive a garlic-like taste in the mouth after DMSO makes contact with their skin. In terms of chemical structure, the molecule has idealized Cs symmetry. It has a trigonal pyramidal molecular geometry consistent with other three-coordinate S(IV) compounds, with a nonbonded electron pair on the approximately tetrahedral sulfur atom. Synthesis and production Dimethyl sulfoxide was first synthesized in 1866 by the Russian scientist Alexander Zaytsev, who reported his findings in 1867. Dimethyl sulfoxide is produced industrially from dimethyl sulfide, a by-product of the K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be represented as . The word ''aqueous'' (which comes from ''aqua'') means pertaining to, related to, similar to, or dissolved in, water. As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Since water is frequently used as the solvent in experiments, the word solution refers to an aqueous solution, unless the solvent is specified. A ''non-aqueous solution'' is a solution in which the solvent is a liquid, but is not water. (See also Solvent and Inorganic nonaqueous solvent.) Characteristics Substances that are ''hydrophobic'' ('water-fearing') do not dissolve well in water, whereas those that are ''hydrophilic'' ('water-friendly') do. An example of a hydrophilic substance is sodium chl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Equilibrium
In a chemical reaction, chemical equilibrium is the state in which both the Reagent, reactants and Product (chemistry), products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the Reversible reaction, reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium. Historical introduction The Concept learning, concept of chemical equilibrium was developed in 1803, after Claude Louis Berthollet, Berthollet found that some chemical reactions are Reversible reaction, reversible. For any reaction mixture to exist at equilibrium, the reaction rate, rates of the forward and backward (reverse) reactions must be equal. In the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Tank
An oxygen tank is an oxygen storage vessel, which is either held under pressure in gas cylinders, or as liquid oxygen in a cryogenic storage tank. Uses Oxygen tanks are used to store gas for: * medical breathing at medical facilities and at home * breathing at altitude in aviation, either in a decompression emergency, or constantly (as in unpressurized aircraft) * oxygen first aid kits * oxygen therapy * gas blending, for creating diving breathing mixes such as nitrox, trimix and heliox * open-circuit scuba sets - mainly used for accelerated decompression in technical diving * some types of diving rebreather: oxygen rebreathers and fully closed circuit rebreathers * use in climbing, "Bottled oxygen" refers to oxygen tanks for mountaineering * industrial processes, including the manufacture of steel and monel * oxyacetylene welding equipment, glass lampworking torches, and some gas cutting torches * use as liquid rocket propellants for rocket engines * athletes, specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firefighter
A firefighter is a first responder and rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten life, property, and the environment as well as to rescue people and in some cases or jurisdictions also animals from dangerous situations. Male firefighters are sometimes referred to as firemen (and, less commonly, a female firefighter as firewoman). The fire service, also known in some countries as the fire brigade or fire department, is one of the three main emergency services. From urban areas to aboard ships, firefighters have become ubiquitous around the world. The skills required for safe operations are regularly practised during training evaluations throughout a firefighter's career. Initial firefighting skills are normally taught through local, regional or state-approved fire academies or training courses. Depending on the requirements of a department, additional skills and certifications such as technical rescue and pre-hospit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
