What do cfcs contain

Very little chlorine exists naturally in the atmosphere — but CFCs are an efficient way of introducing it into the ozone layer. Ultraviolet UV radiation, at the ozone stratospheric height of between 20 to 30 kilometres 12 to 19 mi above Earth, breaks down the CFC and releases the chlorine. Under particular conditions, the chlorine can destroy large amounts of ozone. CFCs have an atmospheric lifetime of 20 — years.

One free chlorine atom from a CFC molecule can destroy large amounts of ozone molecules over that time — and will continue to do so for well into this century. In a milestone of international co-operation, governments gathered in Canada in as fear of continued depletion of the ozone layer mounted up. The result was the Montreal Protocol that called for significant reductions in the production of CFCs. Although pockets of production continue to exist, general prohibition is likely to eliminate CFCs shortly.

HCFCs are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer. Nevertheless, a significant amount hydrochlorofluorocarbons reached the stratosphere to release more chlorine than predicted. HCFCs are scheduled to be phased-out by HFCs are organofluorine compounds that contain hydrogen, carbon and fluorine.

Importantly they do not contain chlorine and therefore do not have any potential for the destruction of ozone. Experts now believe that under special circumstances this chlorine destroys parts of the ozone layer, a rarity that has been observed over Antarctica and as a result of this release, environmentalists have also seen an increase in ultraviolet radiation causes damage to humans.

Because of these harmful effects, the production of many of these products ceased in the early s. However, it is a compound still made in many countries for certain products. For instance, some aircraft products need the halon fire suppression system needs CFCs as there a no suitable product alternatives. Most manufacturers using CFCs recycle the compound through halon banks. This type of industry ensures that the discharge only occurs in an emergency and tries to conserve the product to keep it from harming the environment.

Because of the damage to the ozone layer, in the s, scientists began researching to find alternatives to Chlorofluorocarbons. This research began when the first reports of stratospheric ozone damage happened.

They found that hydrochlorofluorocarbons were not as stable in the lower atmosphere so they could be broken down before reaching the ozone layer.

Even so, a certain amount of HCFCs do break down in the ozone layer and contribute to a significant chlorine buildup. Even so, current alternatives have a shorter lifetime in lower atmospheres. Hydrocarbon compounds are also viable alternatives for mobile air conditioning systems as they do very well in high temperatures.

One of the natural refrigerants such as hydrocarbons mixed with Ammonia and Carbon Dioxide do not have a damaging effect on the environment and are used in commercial and private applications. Early refrigeration products from the late 19th century to the early 20th century used toxic gases like ammonia NH3 , methyl chloride CH3CI , and sulfur dioxide SO2. This sometimes caused fatalities from leakage of these products.

Elkins noaa. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms. Individual CFC molecules are labeled with a unique numbering system. For example, the CFC number of 11 indicates the number of atoms of carbon, hydrogen, fluorine, and chlorine e.

The best way to remember the system is the "rule of 90" or add 90 to the CFC number where the first digit is the number of carbon atoms C , the second digit is the number of hydrogen atoms H , and the third digit is number of the fluorine atoms F. In the example CFC has one carbon, no hydrogen, one fluorine, and therefore 3 chlorine atoms. Refrigerators in the late s and early s used the toxic gases, ammonia NH 3 , methyl chloride CH 3 Cl , and sulfur dioxide SO 2 , as refrigerants.

After a series of fatal accidents in the s when methyl chloride leaked out of refrigerators, a search for a less toxic replacement begun as a collaborative effort of three American corporations- Frigidaire, General Motors, and Du Pont.

Frigidaire was issued the first patent, number 1,,, for the formula for CFCs on December 31, By Frigidaire and its competitors had sold 8 million new refrigerators in the United States using Freon CFC made by the Kinetic Chemical Company and those companies that were licensed to manufacture this compound. Public health codes in many American cities were revised to designate Freon as the only coolant that could be used in public buildings.

During the late s and early s the CFCs made possible an inexpensive solution to the desire for air conditioning in many automobiles, homes, and office buildings. Later, the growth in CFC use took off worldwide with peak, annual sales of about a billion dollars U. Whereas CFCs are safe to use in most applications and are inert in the lower atmosphere, they do undergo significant reaction in the upper atmosphere or stratosphere. In , two University of California chemists, Professor F.

Sherwood Rowland and Dr. Mario Molina, showed that the CFCs could be a major source of inorganic chlorine in the stratosphere following their photolytic decomposition by UV radiation. In addition, some of the released chlorine would become active in destroying ozone in the stratosphere 2. Ozone is a trace gas located primarily in the stratosphere see ozone. Ozone absorbs harmful ultraviolet radiation in the wavelengths between and nm of the UV-B band which can cause biological damage in plants and animals.

A loss of stratospheric ozone results in more harmful UV-B radiation reaching the Earth's surface. Chlorine released from CFCs destroys ozone in catalytic reactions where , molecules of ozone can be destroyed per chlorine atom. A large springtime depletion of stratospheric ozone was getting worse each following year.

This ozone loss was described in by British researcher Joe Farman and his colleagues 3. The ozone hole was different than ozone loss in the midlatitudes. Ozone loss also is enhanced in polar regions as a result of reactions involving polar stratospheric clouds PSCs 5 and in midlatitudes following volcanic eruptions.

The need for controlling the CFCs became urgent. This international agreement included restrictions on production of CFC, , , , , and the Halons chemicals used as a fire extinguishing agents.

An amendment approved in London in was more forceful and called for the elimination of production by the year The environmental concern for CFCs follows from their long atmospheric lifetime 55 years for CFC and years for CFC, CCl 2 F 2 9 which limits our ability to reduce their abundance in the atmosphere and associated future ozone loss.

This resulted in the Copenhagen Amendment that further limited production and was approved later in The manufacture of these chemicals ended for the most part on January 1, The only exceptions approved were for production within developing countries and for some exempted applications in medicine i.