Intermediate Topic 1050 of 1102 Biochemistry, Environment & Industry

CFCs

Chlorofluorocarbons were refrigerants phased out because of ozone damage.

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In-depth explanation of CFCs

Chlorofluorocarbons, or CFCs, are compounds of carbon, chlorine and fluorine such as CCl2F2, known as CFC-12 or Freon-12. They were introduced in the 1930s as non-toxic, non-flammable, stable refrigerants, aerosol propellants and foam blowing agents. Their chemical stability is the reason they survive long enough to reach the stratosphere and destroy ozone. Because of ozone depletion they were phased out under the Montreal Protocol, and they were replaced by hydrochlorofluorocarbons and then hydrofluorocarbons, which contain no chlorine but are potent greenhouse gases. Newer hydrofluoroolefins and natural refrigerants such as ammonia and CO2 are now used.

Going deeper: CFCs

Key ideas: Chlorofluorocarbons such as CFCl3 (CFC-11) and CF2Cl2 (CFC-12) were used in refrigerators, aerosols and foams since they are nonflammable, nontoxic and unreactive. Unreactive in the troposphere, they reach the stratosphere, where UV breaks the C-Cl bond to release Cl radicals. Replacements: HCFCs, then HFCs (no chlorine, but strong greenhouse gases), now HFOs.

Common mistakes and connections: Students think CFCs are heavier than air and sink; they are well mixed by winds. Cl- ions in salt do not harm ozone because they are not radicals. Their lifetime is 50 to 100 years. Links to ozone depletion, halogen bond strengths and Montreal Protocol.

Visualization of CFCs

Ozone depletion potential relative to CFC-11. Replacing CFCs with chlorine-free HFCs removes the ozone threat, though they remain greenhouse gases. The interactive lesson shows this as a live animation or chart.

Worked example and use case

Freon-12 was widely used in domestic refrigerators before its phase-out.

Frequently asked questions about CFCs

What is CFCs?

Chlorofluorocarbons were refrigerants phased out because of ozone damage.

Is CFCs a beginner, intermediate or advanced topic?

CFCs is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.

What should I learn before CFCs?

Study these earlier topics in Biochemistry, Environment & Industry first: Greenhouse Gases, Carbon Cycle, Ozone Layer Depletion.

What comes after CFCs?

The next topics in Biochemistry, Environment & Industry are Smog and Particulate Matter.

Can I practise CFCs with quizzes?

Yes. The interactive lesson includes a self-check question on CFCs, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.

Where CFCs fits in Biochemistry, Environment & Industry

CFCs is topic 75 of 127 in Biochemistry, Environment & Industry.