When high-energy ultraviolet rays strike ordinary oxygen molecules O 2 , they split the molecule into two single oxygen atoms, known as atomic oxygen. The most common source of CFCs are refrigerants, but fire suppression systems for aircraft and aerosols also emit CFCs into the atmosphere. CFCs are compounds made up of chlorine, fluorine and carbon bound together. Chlorofluorocarbons CFCs are highly stable compounds that were used as propellents in spray cans and in refrigeration units.
Freons are colorless, odorless, nonflammable, noncorrosive gases or liquids. Their usage grew enormously over the years.
Sciencing Video Vault. Use of CFCs is restricted to equipment placed into use prior to 1996. Types of Scrubbers. Given sufficiently large variations in temperature and pressure, air parcels containing contaminants can be transported through the troposphere and into the stratosphere, in much the way that a hot air balloon can be used to loft people high above the ground and transport them from one place to another.
Predictions of significant increases in the incidence of skin cancer resulting from continued use of CFCs spurred international action. When a free chlorine atom reacts with gases such as methane CH 4 , it is bound up into a molecule of hydrogen chloride HCl , which can be carried downward from the stratosphere into the troposphere, where it can be washed away by rain.
Retrieved from https: The most common emitter of CFCs are refrigerants, particularly those used after the 1930s. For example, the two gases carbon tetrafluoride CF 4 , produced mainly as a by-product of the manufacture of aluminum and CFC-11 CCl 3 F, used in a variety of human activities are both heavier than air.
Over the Earth's lifetime, natural processes have regulated the balance of ozone in the stratosphere.
It seemed that, because of his focus on CFCs and ozone depletion, he started getting fewer invitations to speak. The CFCs are a group of aliphatic organic compounds containing the elements carbon and fluorine, and, in many cases, other halogens especially chlorine and hydrogen. They are several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. Technical Divisions Collaborate with scientists in your field of chemistry and stay current in your area of specialization.
CFCs have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time. Measurements show it to be nearly uniformly distributed throughout the atmosphere as illustrated in the figure below, the abundance of CF 4 is nearly the same at all altitudes where measurements have been made. These irregularities make some parcels of air buoyant, which results in the transport of pollutants throughout the atmosphere.
We once did a descent directly over the North Pole and found uniform mixing in the lower atmosphere, and slightly less CFC-11 in the stratosphere. Natural reactions other than the "ozone-oxygen cycle" described above also affect the concentration of ozone in the stratosphere. Free chlorine atoms then react with ozone molecules, taking one oxygen atom to form chlorine monoxide and leaving an ordinary oxygen molecule.