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Dibromodifluoromethane
Dibromodifluoromethane is a mixed halomethane. It is a colorless non-flammable liquid. Along with Halons 1211, 2402, and 1301, it is one of the most effective fire extinguishers A fire extinguisher is a handheld active fire protection device usually filled with a dry or wet chemical used to extinguish or control small fires, often in emergencies. It is not intended for use on an out-of-control fire, such as one which ha ..., however, it is also very toxic. It is a class I ozone depleting substance (ODS). Table of physical properties References External links * * Photolysis of dibromodifluoromethane at 265 nmRaman and infrared spectra of solid dibromodifluoromethane {{fluorine compounds Halomethanes Fire suppression agents Ozone depletion Organobromides Organofluorides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halomethane
Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms ( F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and human-made, most notably as refrigerants, solvents, propellants, and fumigants. Many, including the chlorofluorocarbons, have attracted wide attention because they become active when exposed to ultraviolet light found at high altitudes and destroy the Earth's protective ozone layer. Structure and properties Like methane itself, halomethanes are tetrahedral molecules. The halogen atoms differ greatly in size and charge from hydrogen and from each other. Consequently, most halomethanes deviate from the perfect tetrahedral symmetry of methane.Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. The ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Depletion Potential
The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for example, has an ODP of 0.05. CFC 11, or R-11 has the maximum potential amongst chlorocarbons because of the presence of three chlorine atoms in the molecule. The first proposal of ODP came from Wuebbles in 1983. It was defined as a measure of destructive effects of a substance compared to a reference substance. Precisely, ODP of a given substance is defined as the ratio of global loss of ozone due to the given substance to the global loss of ozone due to CFC-11 of the same mass. ODP can be estimated from the molecular structure of a given substance. Chlorofluorocarbons have ODPs roughly equal to 1. Brominated substances have usually higher ODPs in range 5–15, because of the more aggressive bromine reaction with ozone. Hydrochlorofluorocarbons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Depletion
Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main causes of ozone depletion and the ozone hole are manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release atoms from the halogen group through photodissociation, which ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Suppression Agents
Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames are produced. The ''flame'' is the visible portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different. Fire in its most common form can result in conflagration, which has the potential to cause physical damage through burning. Fire is an important process that affects ecological systems around the globe. The positive effects of fire include stimulating growth and maintaining various ecological systems. Its negative effects include hazard to life and property, atmospheric pollution, and water contamination. If fire re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halomethanes
Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms ( F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and human-made, most notably as refrigerants, solvents, propellants, and fumigants. Many, including the chlorofluorocarbons, have attracted wide attention because they become active when exposed to ultraviolet light found at high altitudes and destroy the Earth's protective ozone layer. Structure and properties Like methane itself, halomethanes are tetrahedral molecules. The halogen atoms differ greatly in size and charge from hydrogen and from each other. Consequently, most halomethanes deviate from the perfect tetrahedral symmetry of methane.Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. The ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. It is a trace gas in Earth's atmosphere at 421 parts per million (ppm), or about 0.04% by volume (as of May 2022), having risen from pre-industrial levels of 280 ppm. Burning fossil fuels is the primary cause of these increased CO2 concentrations and also the primary cause of climate change.IPCC (2022Summary for policy makersiClimate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Warming Potential
Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time frame. Carbon dioxide equivalent (e or eq or -e) is calculated from GWP. For any gas, it is the mass of that would warm the earth as much as the mass of that gas. Thus it provides a common scale for measuring the climate effects of different gases. It is calculated as GWP times mass of the other gas. Methane has GWP (over 100 years) of 27.9 meaning that, for example, a leak of a tonne of methane is equivalent to emitting 27.9 tonnes of carbon dioxide. Similarly a tonne of nitrous oxide, from manure for example, is equivalent to 273 tonnes of carbon dioxide. Values Carbon dioxide is the reference. It has a GWP of 1 regardless of the time period used. emissions cause increases in atmospheric concentrations of that will last thousands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichlorofluoromethane
Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a chlorofluorocarbon (CFC). It is a colorless, faintly ethereal, and sweetish-smelling liquid that boils around room temperature. CFC-11 is a Class 1 ozone-depleting substance which damages Earth's protective stratospheric ozone layer. Historical use Trichlorofluoromethane was first widely used as a refrigerant. Because of its high boiling point (compared to most refrigerants), it can be used in systems with a low operating pressure, making the mechanical design of such systems less demanding than that of higher-pressure refrigerants R-12 or R-22. Trichlorofluoromethane is used as a reference compound for fluorine-19 NMR studies. Trichlorofluoromethane was formerly used in the drinking bird novelty, largely because it has a boiling point of . The replacement, dichloromethane, boiling point , requires a higher ambient temperature to work. Prior to the knowledge of the ozone depletion potential of chlorin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Dipole Moment
In physics, a dipole () is an electromagnetic phenomenon which occurs in two ways: *An electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple example of this system is a pair of charges of equal magnitude but opposite sign separated by some typically small distance. (A permanent electric dipole is called an electret.) *A magnetic dipole is the closed circulation of an electric current system. A simple example is a single loop of wire with constant current through it. A bar magnet is an example of a magnet with a permanent magnetic dipole moment. Dipoles, whether electric or magnetic, can be characterized by their dipole moment, a vector quantity. For the simple electric dipole, the electric dipole moment points from the negative charge towards the positive charge, and has a magnitude equal to the strength of each charge times the separation between the charges. (To be precise: for the definition of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halon 1211
Bromochlorodifluoromethane (BCF), also referred to by the code numbers Halon 1211 and Freon 12B1, is a haloalkane with the chemical formula carbon, Cfluorine, F2chlorine, Clbromine, Br. It is used for fire suppression, especially for expensive equipment or items that could be damaged by the residue from other types of extinguishers. Use as a fire extinguishing agent Brominated haloalkanes were first used during World War II in fire extinguishers for aircraft and tanks. BCF was introduced as an effective gaseous fire suppression agent in the mid-1960s for use around highly valuable materials in places such as museums, Mainframe computer, mainframe rooms, and telecommunication telephone exchange, switching centers. BCFs were also widely used in the maritime industries in the engine rooms of ships and also in the transport industry in vehicles. Its efficiency as a fire extinguishing agent has also led it to be the predominant choice of fire extinguishing agent on commercial aircraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractive Index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, , where ''θ''1 and ''θ''2 are the angle of incidence and angle of refraction, respectively, of a ray crossing the interface between two media with refractive indices ''n''1 and ''n''2. The refractive indices also determine the amount of light that is reflected when reaching the interface, as well as the critical angle for total internal reflection, their intensity ( Fresnel's equations) and Brewster's angle. The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is , and similarly the wavelength in that medium is , where '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Critical Temperature
Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in mission and business critical information systems *Critical theory, a school of thought that critiques society and culture by applying knowledge from the social sciences and the humanities * Critically endangered, a risk status for wild species *Criticality (status), the condition of sustaining a nuclear chain reaction Art, entertainment, and media * ''Critical'' (novel), a medical thriller written by Robin Cook * ''Critical'' (TV series), a Sky 1 TV series * "Critical" (''Person of Interest''), an episode of the American television drama series ''Person of Interest'' *"Critical", a 1999 single by Zion I People *Cr1TiKaL (born 1994), an American YouTuber and Twitch streamer See also *Critic *Criticality (other) *Critical Conditi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
