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Chlorofluorocarbons are a combination of toxic gaseous compounds composed of Carbon, Chlorine, Fluorine and hydrogen. They are present in refrigerators, cleaning solvents, and aerosol sprays that cause a direct impact on the environment due to their toxicity and harmfulness. The chemical formula of Chlorofluorocarbon is CCl2F2. Chlorofluorocarbons were once in high usage as a refrigerant at the time of their formulation. CFCs were used by replacing the chemicals that were harmful to human health.
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Keyterms: Chlorofluorocarbons, Carbon, Chlorine, Fluorine, Hydrogen, Environment, Halogen atoms, Atoms, Toxic gas, Gaseous compounds, Dichlorodifluoromethane
Classification of CFC Gases
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Chlorofluorocarbons are classified as halocarbons. Halocarbons are a class of compounds containing atoms of carbon and halogen atoms. CFC molecules are identified with a unique numbering system. For example- CCl3F as CFC-11. CFC number 11 indicates a number of atoms of carbon, hydrogen, fluorine, and chlorine. Dichlorodifluoromethane is the most common example of CFC gas.
Read more: Gamma Radiation
How do CFCs come into Existence?
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Before Chlorofluorocarbons, toxic gases such as Ammonia, Methyl Chloride, and Sulfur Dioxide were used in the refrigerators. But, after a series of fatal incidents that came into notice of the leakage of methyl chloride from refrigerators, the search for less toxic substance replacement began. CFCs (Chlorofluorocarbons) were first found and came into existence in 1930. CFCs were earlier used as the safest chemicals for refrigerators. They are now used in commercial applications in large numbers.
Properties of Chlorofluorocarbons
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- The physical properties of CFCs are altered by the changes in numbers and identities of the halogen atoms.
- CFCs have higher boiling points because chlorine has more polarity than fluoride.
- CFCs are useful solvent and are also considered as an ideal refrigerant.
- CFCs are less flammable than methane.
- The density of CFCs are higher than alkanes as the number of chlorides is proportional to the density of these compounds.
Read more: Effects of Radiation
Impact of Chlorofluorocarbons on Environment
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Despite being safe to use in most applications and less reactive and flammable, CFCs are termed as the major threat to the Environment. They are the major cause of ozone layer depletion because they are made up with the most toxic and harmful gases.
- CFCs are the major source of inorganic chlorine in the stratosphere that will result in the high decomposition of the UV radiations. CFCs do undergo the major significant reaction in the upper atmosphere– stratosphere resulting in the increasing risk of UV radiations.
- CFCs atmospheric effects are not limited to the ozone layer depletion only as the infrared absorption band present in the atmosphere prevents heat from escaping from the earth’s atmosphere. CFCs have their strongest absorption bands from C-F and C-CI bonds in the spectral region of 7.8-15.3 m, referred to as the Atmospheric Window.
- The strength of CFC absorption bands and its unique susceptibility at a wavelength where CFCs absorb creates a super greenhouse gas effect from CFC.
- The ozone layer absorbs harmful ultraviolet radiation with a wavelength between 280 and 320 nm that can cause serious biological damage to plants and animals. But the depletion or hole in the ozone layer or stratospheric ozone is causing harmful UV radiations to reach the earth’s surface causing big damage.
- The chlorine released from CFCs destroys Ozone in catalytic reactions where 100,000 molecules of ozone can be destroyed per chlorine atom.
- UV radiations caused by depletion of the Ozone layer affect human health that includes - aging of the skin, damage to skin cells, and various types of skin cancers. It also causes cataracts, also known as the snow-blindness that is caused due to the inflammation of the cornea in the eyes.
- An international treaty, known as the Montreal Protocol was made after recognizing the deadly effects caused by ozone depletion.
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| Displacement Reaction | Types of Radiation | Infrared Radiation |
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Things to Remember
- Chlorofluorocarbons are a combination of toxic gaseous compounds.
- They are composed of Carbon, Chlorine, Fluorine, and hydrogen. They are present in refrigerators, cleaning solvents, and aerosol sprays that cause a direct impact on the environment due to their toxicity and harmfulness. The chemical formula of Chlorofluorocarbon is CCl2F2.
- Chlorofluorocarbons were created with the vision of finding less toxic gaseous compounds in place of toxic compounds but resulted in the major threat to the Earth’s protective layer– Ozone.
- Chlorofluorocarbons have multiple effects on our environment.
- An international treaty was made to prevent the usage of CFC across the globe to lessen the harm to the Ozone layer.
- The physical properties of chlorofluorocarbons are similar to the physical properties of halogen atoms.
Sample Questions
Ques: What are the applications of Chlorofluorocarbons? (2 Marks)
Ans: Chlorofluorocarbons have a variety of applications as they are less toxic, inflammable and reactive. These characteristics of CFCs makes them one of the most used chemicals. Every possible mixture of fluorine, hydrogen, chlorine, and ethane are commercially used. For example: solvents, propellants in medicinal applications, refrigerators, and blowing agents.
Ques: What is the process of preparation of Chlorofluorocarbons? (3 Marks)
Ans: CFCs are made by the halogen exchange of chlorinated methane and ethane.
HCCl3 + 2 HF → HCF2Cl + 2HCl.
The preparation process of Chlorofluorocarbons begins with the reaction of Carbon with Chlorine. This relates to the new preparation process of halogenated halocarbons compounds containing only carbon, chlorine, and fluorine and thus Chlorofluorocarbons are formed.
Ques: What was the reason behind the invention of CFCs? (3 Marks)
Ans: Before the invention of CFC, toxic gases including ammonia, methyl chloride, and sulfur dioxide were used in refrigerators and other solvents. But when the incidents of the leakage of methyl chloride came to the notice from refrigerators in the late 1920s, the search for the less toxic and flammable replacement began. Methyl chloride leakage from the refrigerators was becoming a major threat to livelihood as it is among the top harmful gaseous compounds.
Ques: Which Chlorofluorocarbons gas among Chlorine, Fluorine, Sulphur dioxide, and Nitrogen peroxide is more chemically harmful to Ozone? (3 Marks)
Ans: Chlorine is the most chemically harmful chlorofluorocarbon gas for the Ozone Layer. It causes the depletion of the Ozone layer and also various severe life-threatening health problems to human and animal health. Chlorofluorocarbon is digging the hole in the Ozone layer due to its increase and as a result, the Ozone layer is unable to dilute the UV rays coming to the earth’s surface.
Skin disease, eye infections, and mutation in cells are the most common harmful effects caused by the depletion of the ozone layer.
Ques: What is the Ozone layer and how is it affected by CFCs? (5 Marks)
Ans: Ozone layer is the protective layer that surrounds the earth’s uppermost layer and protects the living beings of earth from the Ultraviolet and harmful radiations coming from the Sun. 90% of the Ozone occurs in the Stratosphere, a region from 10-18km to 50km above Earth’s surface. The atmosphere in the stratosphere rises with the phenomenon created by the absorption of solar radiation by the Ozone layer.
Chlorofluorocarbon is creating a hole in the Ozone layer. The Ozone layer is unable to dilute the UV rays coming to the earth’s surface. Chlorofluorocarbons and the hole that is expanding in the ozone layer is allowing rays to reach the earth’s surface which further results in a variety of harmful effects.
Ques: What are the methods that are used to prevent Ozone layer depletion? (5 Marks)
Ans: Methods that are used to prevent Ozone layer depletion are as follows:
- Buying air-conditioning and refrigerant applications or types of equipment that do not use CFCs as their refrigerant.
- Consuming aerosol products that do not use CFCs as the propellants.
- Prevent refrigerant leakage through regular maintenance of the air-conditioning appliances.
- By minimizing the usage of cars and using the best transport options like – Urban, Bicycle, and through walking.
Ques: What are the advantages of reducing the usage of Chlorofluorocarbons? (5 Marks)
Ans: Minimizing the usage of Chlorofluorocarbons in our surroundings, the world has witnessed major results and all of the results are a good sign. A few of them includes:-
- Due to the high alertness and awareness regarding ozone layer depletion and to reduce the harmful effects of Chlorofluorocarbons on the environment, several active on-charge groups are coming forward to dispose of CFCs from the surroundings.
- CFCs have been banned in several nations since 1996 to prevent Ozone layer depletion.
- According to NASA’s report in 2018, the hole in the Ozone layer has started to close.
- In 2019, the smallest hole in the Ozone layer ever since its discovery was recorded.
Ques: What is the Montreal Protocol and how is it an advantage for the Environment? (5 Marks)
Sol- Montreal Protocol is the agreement that regulates the production and consumption of at least 100 chemicals that are in the list of chemicals depleting the ozone layer. These are referred to as Ozone Depleting Substances (ODS).
ODS then phases down the harmful chemicals like CFCs in the step by step manner by Montreal Protocol through phasing down the production and consumption for the same. Montreal protocol works on the timetable according to the different nations. This treaty includes the responsibilities given to all of the parties included in this agreement that varies from phasing out ODS to trade of ODS, annual reporting of data, national licensing systems, ODS import and exports, and many more linked to ODS.
Due to the rapid development in science, technology, and economy, the treaty evolves and updates over time. Countries have equal but different responsibilities with deadlines and measured commitments.
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