What is Freon Gas?
The Freon gas is a colourless, odourless, noninflammable, noncorrosive gas of low toxicity introduced as refrigerants in the 1930s. They also proved helpful as propellants for aerosols and in numerous technical applications. Freon (trademark) comprises several simple fluorinated aliphatic organic compounds utilized for commercial and industrial purposes. Apart from fluorine and carbon, Freons often include hydrogen, bromine, or chlorine. As such, Freons are chlorofluorocarbons (CFCs), hydrofluorocarbons (HCFCs) and related compounds.
The Freons in chemistry have meagre boiling points, low surface tension, and low viscosity, making them quite valuable refrigerants. They are incredibly stable and inert substances. The Freons do not pose a fire hazard and don't give off a detectable odour while circulating through refrigerators and air conditioners. Dichlorodifluoridemethane (Freon 12), trichlorofluoromethane (Freon 11), chlorodifluoromethane (Freon 22), dichlorotetrafluoroethane (Freon 114), and trichlorotrifluoroethane (Freon 113) are the crucial members of the family.
The History of Freons
Frederic Swarts synthesized the first CFCs during the 1890s. By the late 1920s, a research team was curated by Charles Franklin Kettering in General Motors to substitute dangerous refrigerants like ammonia. Thomas Midgley, Jr, headed the group. In 1928, the team enhanced the synthesis of CFCs and demonstrated their utility, stability and non-toxicity. Kettering patented a refrigerating apparatus to use the gas; he issued it to Frigidaire, a wholly-owned subsidiary of General Motors. In 1930, General Motors and Du Pont formed Kinetic Chemicals to produce Freon. Their product was dichlorodifluoromethane and called “Freon-12”, "R-12", or "CFC-12". The number after the R is a refrigerant class number developed by DuPont to identify single halogenated hydrocarbons and other refrigerants besides halocarbons systematically.
Most CFCs' uses are now banned or severely restricted by the Montreal Protocol of August 1987, as they are responsible for ozone depletion. Brands of Freon containing hydrofluorocarbons (HFCs) instead have replaced many uses, but they, too, are under strict control under the Kyoto Protocol, as they are deemed "super-greenhouse effect" gases.
Freon Formula
Du Pont introduced a naming system for CFCs as per the fluorine, hydrogen, and carbon atoms. The number that is farthest from the right is the number of fluorines. The second number from the right is the number of hydrogen plus one. Lastly, the third digit from the right is the number of carbons minus one. Thus, CHClF₂ is Freon 22, CCl₂F₂ is Freon 12, and likewise.
You have to specify which Freon formula you are asking for. CFCl₃, CF₂Cl₂ - these all are Freons.
You can understand the chemical formula of Freons by using the following method.
Freon (no. of carbons-1) (no. of hydrogen+1) (no. of fluorine)
For example:-CFCl₃ Freon 11
Here, the number of carbon =1 and 1–1=0, so there is no requirement to put the number of hydrogen, zero and 0+1=1 number of fluorine=1.
Freon Gas Structure
Freons are insoluble in water, and their general chemical inertness is phenomenal. They stay stable in hot concentrated mineral acids and are unaffected by molten sodium. Thus, the Freon gas structure results from the solid C-F bonds that become shorter as the fluorine atom of carbon ratio increases. Hence, the C-F bond length is 1.29 angstroms CH₃F, 1.358 angstroms in CF₂, and so forth.
In the stratosphere, Freons die out when exposed to ultraviolet light.
CCl₂F₂ (g) + uv rays —---> CF₂Cl(g) + Cl(g) and the chlorine atoms destroy the ozone layer.
There are over 300 “Freon gases”. Some are CFCs, some are HCFCs, and many have no chlorine in them.
So “Freon” is a brand name and means nothing else. The correct term is “Refrigerant”, which can include nitrogen, propane, alcohol, and a whole plethora of other gasses.
Uses of Freons
On account of their low boiling points and low viscosity, the uses of Freons are innumerable. The primary refrigerant uses include -
Refrigerators
Air-conditioning systems
Other uses of Freons are -
Aerosol propellants
Foam-blowing agents
Solvents
Glass chillers
Polymer intermediates
Freons also have applications in the following areas -
Fire extinguishers
Anaesthetics
Besides, Freons have been used as inhalants by many teenagers and young adults. Inhalants are everyday legal substances which when inhaled intensely, give a high. People may inhale refrigerant gases, paint thinners, sprays, or gasoline to get a kick.
But the use of Freons has been banned in most countries due to the potential environmental and health effects of ozone depletion and the greenhouse effect.
Conclusion
Nowadays, Freons are banned by an international agreement, and everyone is looking for substitutes. The United States banned CFC production in 1977, and that ban continues. Non-ozone layer depleting alternatives of the compounds are hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) such as CH₂FCF₃ (HFC 134a) and CHCl₂CF₃ (HCFC 123). In 1987, the Montreal Protocol asserted for decreasing CFCs, and a 1992 amendment to the treaty ended the production of CFC. By 1993, the emissions of CFC declined dramatically.
A total of 148 nations are now signatory to the Montreal Protocol, which calls for HCFCs to be slowly removed by 2020 and alternated with HFCs, containing no chlorine and a short lifetime. The illegal market of CFCs is of such proportion that ‘Scientific American’ has reported that the illegal trade of CFC is one of the biggest dangers to the ozone layer recovery.
FAQs on Freon
1. What are Freons and what is their general chemical composition?
Freons are a group of chemical compounds known as chlorofluorocarbons (CFCs). They are synthetic, unreactive, non-toxic, and non-flammable gases or liquids. Chemically, they are derivatives of simple hydrocarbons like methane and ethane, where hydrogen atoms are replaced by chlorine (Cl) and fluorine (F) atoms. A common example is dichlorodifluoromethane (CCl₂F₂).
2. What are the key physical and chemical properties of Freons?
Freons are valued for their unique set of properties, which made them useful in industry. Key properties include:
- High Stability: They are chemically inert and stable under normal conditions.
- Low Boiling Points: They are easily converted from liquid to gas and back, making them excellent refrigerants.
- Non-toxic and Non-corrosive: They are generally safe for handling and do not damage the containers they are stored in.
- Odourless and Colourless: They are non-intrusive in their applications.
3. What were the primary industrial applications of Freons before they were phased out?
Due to their desirable properties, Freons were widely used across several industries. Their primary applications included:
- Refrigerants: Used in refrigerators and air conditioning systems (e.g., Freon-12).
- Aerosol Propellants: Used in spray cans for products like deodorants, insecticides, and paints.
- Blowing Agents: Used in the production of polymer foams, such as polystyrene.
- Solvents: Used for cleaning electronic components and degreasing metals.
4. What is Freon-12, and what is its chemical name and formula?
Freon-12 is one of the most well-known types of Freon. Its chemical formula is CCl₂F₂, and its IUPAC name is dichlorodifluoromethane. It was extensively used as a refrigerant in air conditioning systems and as a propellant in aerosol cans until its production was banned due to its severe impact on the ozone layer.
5. How exactly do Freons contribute to the depletion of the ozone layer?
Freons cause ozone depletion through a destructive radical chain reaction. In the stratosphere, intense ultraviolet (UV) radiation breaks the C-Cl bond in a Freon molecule, releasing a highly reactive chlorine radical (Cl•). This chlorine radical then reacts with an ozone (O₃) molecule, breaking it down into oxygen (O₂) and a chlorine monoxide radical (ClO•). The ClO• radical can then react with an oxygen atom to regenerate the chlorine radical (Cl•), which is then free to destroy another ozone molecule. A single chlorine radical can destroy thousands of ozone molecules before it is removed from the stratosphere.
6. Why are Freons so stable in the lower atmosphere but highly destructive in the stratosphere?
The stability of Freons in the lower atmosphere (troposphere) is due to the strength of their carbon-halogen bonds. They are inert and do not react with other atmospheric gases. However, in the upper atmosphere (stratosphere), they are exposed to high-energy UV-C radiation from the sun. This radiation is powerful enough to break the C-Cl bond, a process called photolysis, which releases the destructive chlorine radicals. This crucial difference in UV exposure explains their contrasting behaviour in different atmospheric layers.
7. How does the naming system for Freons (e.g., Freon-11, Freon-12) work?
The numerical naming system for Freons, known as the "Rule of 90," provides a simple way to determine their chemical formula. To find the formula for a Freon-XY compound:
- Add 90 to the number (e.g., for Freon-12, 12 + 90 = 102).
- The first digit (1) represents the number of carbon atoms.
- The second digit (0) represents the number of hydrogen atoms.
- The third digit (2) represents the number of fluorine atoms.
8. What international agreement led to the phasing out of Freons, and what are their modern replacements?
The Montreal Protocol on Substances that Deplete the Ozone Layer, signed in 1987, is the landmark international treaty that mandated the gradual phasing out of CFCs like Freons. As a result, new alternatives were developed. The primary replacements include:
- Hydrochlorofluorocarbons (HCFCs): These were transitional replacements as they have a lower ozone-depleting potential. However, they are also being phased out.
- Hydrofluorocarbons (HFCs): These compounds do not contain chlorine and therefore do not deplete the ozone layer. However, they are potent greenhouse gases.
- Hydrofluoroolefins (HFOs): A newer generation of refrigerants with very low global warming potential.
9. How do the environmental impacts of CFCs, HCFCs, and HFCs compare?
The environmental impacts of these compounds are compared based on two key metrics: Ozone Depletion Potential (ODP) and Global Warming Potential (GWP).
- CFCs (Freons): Have a high ODP and a very high GWP. They are destructive to the ozone layer and are potent greenhouse gases.
- HCFCs: Have a low ODP because the presence of hydrogen makes them less stable in the atmosphere. However, they still have a significant GWP.
- HFCs: Have an ODP of zero because they lack chlorine. This makes them safe for the ozone layer, but they have a very high GWP, contributing to climate change.
