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1,2-Dichlorotetrafluoroethane, or R-114, also known as cryofluorane , is a chlorofluorocarbon (CFC) with the molecular formula ClF 2 CCF 2 Cl. Its primary use has been as a refrigerant. It is a non-flammable gas with a sweetish, chloroform-like odor with the critical point occurring at 145.6 °C and 3.26 MPa. When pressurized or cooled, it is a ...
Chlorofluorocarbons (CFCs): when derived from methane and ethane these compounds have the formulae CCl m F 4−m and C 2 Cl m F 6−m, where m is nonzero. Hydro-chlorofluorocarbons (HCFCs): when derived from methane and ethane these compounds have the formula CCl m F n H 4−m−n and C 2 Cl x F y H 6−x−y, where m, n, x, and y are nonzero.
CFC-113 is a very unreactive chlorofluorocarbon. It remains in the atmosphere about 90 years, [ 9 ] sufficiently long that it will cycle out of the troposphere and into the stratosphere . In the stratosphere, CFC-113 can be broken up by ultraviolet radiation (UV, sunlight in the 190-225 nm range), generating chlorine radicals (Cl•), which ...
In 1978 atmospheric levels of CFC-114a were 0.35 ppt. By 2020 the level was up to 1.13 ppt. [13] CFC-114a appears to be emitted into the atmosphere is South East Asia. [10] The atmospheric natural destruction of CFC-114a is by reaction with atomic oxygen, or breakup by ultraviolet light. [10]
Tetrachloro-1,2-difluoroethane is a chlorofluorocarbon known as Freon 112, CFC-112 or R-112. It has a symmetrical structure CCl 2 FCCl 2 F and so can be called symmetrical tetrachlorodifluoroethane. "Symmetrical" may also be abbreviated to "s-" or "sym-". In contrast an asymmetrical isomer has formula CCl 3 CClF 2.
However, for many rivers in the proximity of humans, the largest input is from sewage whether treated or untreated. The nitrogen derives from breakdown products of proteins found in urine and faeces. These products, being very soluble, often pass through sewage treatment process and are discharged into rivers as a component of sewage treatment ...
A 2018 report to Congress indicated that "at least 126 drinking water systems on or near military bases" were contaminated with PFAS compounds. [8] [9] A 2016 study found unsafe [10] levels of fluorosurfactants in 194 out of 4,864 water supplies in 33 U.S. states. Covering two-thirds of drinking water supplies in the United States, the study ...
Thomas Midgley Jr. (May 18, 1889 – November 2, 1944) was an American mechanical and chemical engineer.He played a major role in developing leaded gasoline (tetraethyl lead) and some of the first chlorofluorocarbons (CFCs), better known in the United States by the brand name Freon; both products were later banned from common use due to their harmful impact on human health and the environment.