What is the full form of CFC
CFC stands for Chlorofluorocarbon. Chemicals with carbon, chlorine and fluoro atoms are known as chlorofluorocarbons (CFCs), and they are neither poisonous nor combustible. They are typically used as solvents, refrigerants, blow ingredients for foams and packaging materials, and in producing aerosol sprays.
CFCs are usually classified under halocarbons, a group of substances that include halogen and carbon atoms. CFC molecules are marked with a different numbering scheme. For instance, the CFC number 11 represents the quantity of carbon, hydrogen, fluorine, and chlorine atoms (e.g. CCl3F as CFC-11). The most efficient way to memorize the system is to use the "rule of 90," which adds an additional 90 to the CFC number, where the first digit stands for the number of carbons (C), the next stands for the number of hydrogen atoms (H), and the third stands for the number of fluorine atoms (F). The formula Cl = 2(C+1) - H - F is used to compute the total amount of chlorine atoms (Cl). In the given example, CFC-11 contains one carbon, one fluorine, no hydrogen, and hence three chlorine atoms.
In the late 1800s and at the beginning of the 1900s, ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2) were utilized as coolants in refrigerators. Three American companies-Frigidaire, General Motors, and Du Pont-joined together to start looking for a less toxic substitute following a string of tragic accidents caused by methyl chloride leaks from refrigerators in the 1920s. Thomas Midgley, Jr. of General Motors created CFCs for the first time in 1928 as safer alternatives for refrigerators used in big commercial applications. On December 31, 1928, Frigidaire got the first patent (number 1,886,339) for the CFC formula. To generate Freon (a DuPont company's leading brand for CFCs) in large quantities, General Motors and Du Pont established the Kinetic Chemical Company in 1930. By 1935, Frigidaire and its rivals had sales worth 8 million in brand-new refrigerators in the U.S. utilizing Freon-12 (CFC-12), which was produced by the Kinetic Chemical Company and other businesses with a manufacturing license. In 1932, the Carrier Engineering Corporation created the "Atmospheric Cabinet," the first self-sufficient house air conditioner, using Freon-11 (CFC-11). Freon has replaced CFC as the primary coolant in large air conditioning systems due to CFC's safety record for nontoxicity. Freon was designated as the only refrigerant that can be used in government buildings in several American cities' amended public health standards. CFCs were employed as propellants for paints, hair conditioners, bug sprays, and other health care goods after World War II. The CFCs made it possible for many cars, houses, and office buildings to affordably address the need for air conditioning in the 1950s and 1960s. Later, the usage of CFCs increased significantly, reaching a peak with yearly sales of nearly $1 billion (U.S.) and the production of more than 1 million metric tonnes.
Despite being neutral in the lower atmosphere and safe to use in the majority of applications, CFCs do experience significant reactivity in the Earth's atmosphere or stratosphere. Two chemists from the University of California, Professor F. Sherwood Rowland and Dr Mario Molina showed in 1974 that the CFCs might be a significant source of inorganic chlorine in the stratosphere following their photolytic breakdown by U.V. radiation. Additionally, part of the chlorine that was released would start to degrade ozone in the stratosphere actively. A trace gas called ozone is primarily found in the stratospheric. The UV-B band, which has hazardous wavelengths between 280 and 320 nm, can affect plants and animals biologically. Ozone absorbs this UV-B band radiation. Less ozone in the stratosphere means more UV-B radiation reaches the Earth's surface, damaging the environment. Ozone is destroyed by chlorine emitted from CFCs in catalytic processes, where each chlorine atom can destroy 100,000 molecules of ozone.
Every year after that, there was a significant stratospheric ozone layer depletion in the spring. Joe Farman and his colleagues, British researchers, first described this ozone loss in 1985. The Antarctic hole present in the ozone layer was the name given to it by others. The ozone hole was distinct from the midlatitude ozone decrease. Due to a number of variables, including the exceptionally cold temperatures in the area, the dynamical isolation of this "hole", and the synergistic interactions of chlorine and bromine, the loss was larger over Antarctica than in the midlatitudes. Ozone loss was also accelerated in midlatitudes after volcanic eruptions and in Polar Regions as a result of processes that involve polar stratospheric clouds (PSCs). As a result, controlling CFCs became urgently necessary.
The Montreal Protocol, to reduce such substances that deplete the Ozone Layer, was signed by 27 countries in 1987. It included a clause requiring a 50% reduction in the generation of these chemicals (CFCs) by the year 2000 from 1986 levels. This international agreement placed limitations on the manufacturing of CFC-11, -12, 113, 114, and 115, as well as the Halon compounds (chemicals used as fire extinguishing agents). A strong amendment enacted in London in 1990 demanded that production be halted by the year 2000. The London Amendment was amended to include the chlorinated solvents carbon tetrachloride (CCl4) and methyl chloroform (CH3CCl3).
Instruments on the deck of the NASA ER-2 aircraft, as well as UARS (Upper Atmospheric Research Satellite), were able to detect significant amounts of reactionary stratospheric chlorine in the manner of chlorine monoxide (Cl2O) over a few areas of North America in the winter months during 1991-92. This type of chlorine could only be produced as a result of the CFCs damaging ozone in the stratosphere. Environmental concerns were raised by the CFCs' prolonged atmospheric lifetime (140 years for CFC-12 and CCl2F2), compared to 55 years for CFC-11, which limited the capacity to reduce their presence in the atmosphere and ensuing future ozone loss. This led to the Copenhagen Amendment, which was later enacted in 1992 and significantly restricted the output of such substances in the atmosphere. On January 1, 1996, production of these compounds largely came to a stop. The only exemptions authorized were for applications in research, and some exempted uses in medical (such as asthma inhalers) and underdeveloped countries. If a signatory nation were to trade or manufacture certain prohibited chemicals, economic and trade sanctions would be applied, according to the Montreal Protocol's enforcement procedures. The number of nations that have ratified the Montreal Protocol today stands at 148. Measurements of CFC-11 and CFC-12 in the atmosphere from 1993 revealed that their growth rates were slowing as a result of both voluntary and required emission reductions. By 1994, the content of several CFCs and a few specific chlorinated solvents had either levelled out or dropped.