Present information from secondary sources to identify alternative chemicals used to replace CFCs and evaluate the effectiveness of their use as a replacement for CFCs
- Hydrochlorofluorocarbon (HCFC): A haloalkane containing hydrogen, chlorine and fluorine atoms.
- HCFCs were the first substances used as replacements for CFCs.
- The carbon-hydrogen (C-H) bonds in HCFCs are susceptible to attack by reactive radicals and atoms in the troposphere, and are therefore decomposed there to a significant extent.
- However, they still diffuse into the stratosphere and cause significant ozone destruction.
- Hydrofluorocarbon (HFC): A haloalkane containing hydrogen and fluorine atoms.
- HFCs are now widely used as replacements for CFCs.
- They contain carbon-hydrogen (C-H) bonds that cause them to undergo some decomposition in the troposphere, and contain no carbon-chlorine (C-Cl) bonds that would form chlorine free radicals in the stratosphere.
- Thus, the ozone-destroying capacity of HFCs is zero.
- The most widely used HFC is 1,1,1,2-tetrafluoroethane, which is used primarily in refrigeration and air conditioning.
- It is more expensive and less efficient than the CFCs it replaces.
- Hydrocarbon: A compound containing only hydrogen and carbon.
- Hydrocarbons have replaced CFCs as propellants in spray cans.