Q.The name of C₂F₄Cl₂ is ___________ a) Freon-112 b) Freon-113 c) Freon-114 d) Freon-115

Freons (chlorofluorocarbons, CFCs) are the chlorofluoro derivatives of methane and ethane, named by a simple digit code, Freon-cba, where c = (carbon atoms - 1), b = (hydrogen atoms + 1), and a = total fluorine atoms -- so CF2Cl2 (0 extra carbons beyond one, 0 H so b=1, 2 F) is Freon-12, and C2F3Cl3 (1 extra carbon so c=1, 0 H so b=1, 3 F) is Freon-113. Freon-12 is manufactured from carbon tetrachloride and hydrogen fluoride over a catalytic amount of antimony pentachloride (CCl4 + 2 HF gives CCl2F2 + 2 HCl) -- this halogen-exchange step is itself called the Swarts reaction, the same named reaction used earlier in the chapter to convert a simple bromoalkane to a fluoroalkane, just applied here to a tetrahalomethane starting material. Freons are highly stable, unreactive, non-corrosive, non-toxic, easily-liquefiab …