Final answer:
When all hydrogen atoms in a hydrocarbon are replaced by chlorine and fluorine, the compound is considered fully halogenated. Compounds like CFCs and HCFCs are examples, with Freon-12 being a fully halogenated CFC used as a refrigerant.
Step-by-step explanation:
If all of the hydrogen atoms have been replaced in the base molecule by chlorine and fluorine, the refrigerant is said to be fully halogenated. This is because the original hydrogen atoms in the hydrocarbon have been substituted with halogen atoms such as chlorine (Cl) and fluorine (F). A halogenated hydrocarbon is a compound in which one or more hydrogen atoms have been replaced by a halogen atom.
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are examples of compounds that can be either fully or partly halogenated. For instance, dichlorodifluoromethane (R-12 or Freon-12) is a fully halogenated chlorofluorocarbon. When all hydrogen atoms are substituted, it results in a stable molecule that has been utilized in a variety of applications including refrigerants and aerosol propellants, although their use is being phased out due to environmental considerations like ozone depletion.