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SF6
Sulfur hexafluoride or sulphur hexafluoride (British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non-flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, is poorly soluble in water but quite soluble in nonpolar organic solvents. It has a density of 6.12 g/L at sea level conditions, considerably higher than the density of air (1.225 g/L). It is generally transported as a liquefied compressed gas. is 23,500 times more potent than as a greenhouse gas but exists in relatively minor concentrations in the atmosphere. Its concentration in Earth's troposphere reached 10.63 parts per trillion (ppt) in 2021, rising at 0.39 ppt/year. The increase over the prior 40 years was driven in large part by the expanding electric power sector, including fugitive emissions from banks of gas contained in its medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disulfur Decafluoride
Disulfur decafluoride is a chemical compound with the formula . It was discovered in 1934 by Kenneth Denbigh, Denbigh and Whytlaw-Gray. Each sulfur atom of the molecule is octahedral, and surrounded by five fluorine atoms and one sulfur atom. The two sulfur atoms are connected by a single bond. In the molecule, the oxidation state of each sulfur atoms is +5, but their Valence (chemistry), valency is 6 (they are hexavalent). is highly toxic, with toxicity four times that of phosgene. It is a colorless liquid with a burnt match smell similar to sulfur dioxide. Production Disulfur decafluoride is produced by photolysis of : : Disulfur decafluoride arises by the decomposition of sulfur hexafluoride. It is produced by the electrical decomposition of sulfur hexafluoride ()—an essentially inert Electrical insulation, insulator used in high voltage systems such as transmission lines, Electrical substation, substations and switchgear. is also made during the production of . Propert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur Tetrafluoride
Sulfur tetrafluoride is the chemical compound with the formula S F4. It is a colorless corrosive gas that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical and specialty chemical industries. Structure Sulfur in SF4 is in the formal +4 oxidation state. Of sulfur's total of six valence electrons, two form a lone pair. The structure of SF4 can therefore be anticipated using the principles of VSEPR theory: it is a see-saw shape, with S at the center. One of the three equatorial positions is occupied by a nonbonding lone pair of electrons. Consequently, the molecule has two distinct types of F ligands, two axial and two equatorial. The relevant bond distances are = 164.3 pm and = 154.2 pm. It is typical for the axial ligands in hypervalent molecules to be bonded less strongl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactive, as it reacts with all other elements except for the light inert gases. Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine which gave the element its name, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the Latin verb meaning 'flow' gave the mineral its name. Proposed as an element in 1810, fluorine proved difficult and dangerous to separate from its compounds, and several early experimenters died or sustained injuries from their attempts. Only in 1886 did French chemist Henri Moissan isolate elemental fluorine using low-temperature electrolysis, a process still employed for moder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypervalent Molecule
In chemistry, a hypervalent molecule (the phenomenon is sometimes colloquially known as expanded octet) is a molecule that contains one or more main group elements apparently bearing more than eight electrons in their valence shells. Phosphorus pentachloride (), sulfur hexafluoride (), chlorine trifluoride (), the chlorite () ion, and the triiodide () ion are examples of hypervalent molecules. Definitions and nomenclature Hypervalent molecules were first formally defined by Jeremy I. Musher in 1969 as molecules having central atoms of group 15–18 in any valence other than the lowest (i.e. 3, 2, 1, 0 for Groups 15, 16, 17, 18 respectively, based on the octet rule). Several specific classes of hypervalent molecules exist: * Hypervalent iodine compounds are useful reagents in organic chemistry (e.g. Dess–Martin periodinane) * Tetra-, penta- and hexavalent phosphorus, silicon, and sulfur compounds (e.g. PCl5, PF5, SF6, sulfuranes and persulfuranes) * Noble gas compounds (ex. xe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul Lebeau
Paul Marie Alfred Lebeau (19 December 1868 – 18 November 1959) was a French chemist. He studied at the elite École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI). Together with his doctoral advisor Henri Moissan he was working on fluorine chemistry discovering several new compounds, like bromine trifluoride, oxygen difluoride, selenium tetrafluoride and sulfur hexafluoride. In 1899 he was able to obtain pure beryllium by electrolysis sodium fluoroberyllate (Na2 eF2. In World War I he improved the gas mask design used by the French army The French Army, officially known as the Land Army (french: Armée de Terre, ), is the land-based and largest component of the French Armed Forces. It is responsible to the Government of France, along with the other components of the Armed Force .... References * 1868 births 1959 deaths 20th-century French chemists ESPCI Paris alumni Commandeurs of the Légion d'honneur Members of the Fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Moissan
Ferdinand Frédéric Henri Moissan (28 September 1852 – 20 February 1907) was a French chemist and pharmacist who won the 1906 Nobel Prize in Chemistry for his work in isolating fluorine from its compounds. Moissan was one of the original members of the International Atomic Weights Committee. Biography Early life and education Moissan was born in Paris on 28 September 1852, the son of a minor officer of the eastern railway company, Francis Ferdinand Moissan, and a seamstress, Joséphine Améraldine (née Mitel). His mother was of Jewish descent, his father was not. In 1864 they moved to Meaux, where he attended the local school. During this time, Moissan became an apprentice clockmaker. However, in 1870, Moissan and his family moved back to Paris due to war against Prussia. Moissan was unable to receive the ''grade universitaire'' necessary to attend university. After spending a year in the army, he enrolled at the Ecole Superieure de Pharmacie de Paris. Scientific career ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Sulfur is the tenth most abundant element by mass in the universe and the fifth most on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum.. Downloahere The greatest commercial use of the element is the producti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Switchgear
In an electric power system, a switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. This type of equipment is directly linked to the reliability of the electricity supply. The earliest central power stations used simple open knife switches, mounted on insulating panels of marble or asbestos. Power levels and voltages rapidly escalated, making opening manually operated switches too dangerous for anything other than isolation of a de-energized circuit. Oil-filled switchgear equipment allows arc energy to be contained and safely controlled. By the early 20th century, a switchgear line-up would be a metal-enclosed structure with electrically operated switching elements using oil circuit breakers. Today, oil-filled equipment has largely been replaced by air-blast, vacuum, or SF6 equip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fugitive Emissions
Fugitive emissions are leaks and other irregular releases of gases or vapors from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition to the economic cost of lost commodities, fugitive emissions contribute to local air pollution and may cause further environmental harm. Common industrial gases include refrigerants and natural gas, while less common examples are perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride. Most occurrences of fugitive emissions are small, of no immediate impact, and difficult to detect. Nevertheless due to rapidly expanding activity, even the most strictly regulated gases have accumulated outside of industrial workings to reach measurable levels globally. Fugitive emissions include many poorly understood pathways by which the most potent and long-lived ozone depleting substances and greenhouse gases enter Earth's atmosphere. In par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parts Per Notation
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, ), parts-per-billion (ppb, ), parts-per-trillion (ppt, ) and parts-per-quadrillion (ppq, ). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it is common to eq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troposphere
The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From the planetary surface of the Earth, the average height of the troposphere is in the tropics; in the middle latitudes; and in the high latitudes of the polar regions in winter; thus the average height of the troposphere is . The term ''troposphere'' derives from the Greek words ''tropos'' (rotating) and '' sphaira'' (sphere) indicating that rotational turbulence mixes the layers of air and so determines the structure and the phenomena of the troposphere. The rotational friction of the troposphere against the planetary surface affects the flow of the air, and so forms the planetary boundary layer (PBL) that varies in height from hundreds of meters up to . The measures of the PBL vary according to the latitude, the landform, and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenhouse Gas
A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane (), nitrous oxide (), and ozone (). Without greenhouse gases, the average temperature of Earth's surface would be about , rather than the present average of . The atmospheres of Venus, Mars and Titan also contain greenhouse gases. Human activities since the beginning of the Industrial Revolution (around 1750) have increased the atmospheric concentration of carbon dioxide by over 50%, from 280 ppm in 1750 to 421 ppm in 2022. The last time the atmospheric concentration of carbon dioxide was this high was over 3 million years ago. This increase has occurred despite the absorption of more than half of the emissions by various natural carbon sinks in the carbon cycle. At current greenhouse gas emission rates, temperatures co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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