3. Most refrigerants utilize the energy involved in the liquid/gas phase change of a molecule, where an ideal refrigerant is noncorrosive, nonflammable, and has a boiling point around the desired temperature. Many fluorinated carbons meet all of these requirements, but the extremely high stability of some (such as CFCs) caused them to be phased out by the Montreal Protocol due to their ozone depleting potential. 3.a. R-12 (CCl2F2) was commonly used in household refrigerators and vehicle air conditioners prior to 1994. What is the correct Lewis structure for R-12