Dichlorodifluoromethane CFC

Unfortunately, the thermodynamically favored reactions of trichlo-rolluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) with water do not proceed to a significant degree below 300 C and at least 200 atm (1 atm = 101.325 kPa) or greater [42] (equation 44) Even at 4000 atm randoimzation rather than complete hydrolysis occurs, leaving another chlorofluorocarbon, chlorotri-fluoromethane (CFC-13), which is also potentially harmful to the earth s ozone layer... 

Chlorofluorocarbon-blown foam blocks are used to insulate the walls and roofs of some buildings, thus reducing heat losses and helping to conserve fossil fuels. In this area, polyurethane foam competes with polystyrene foam, which until recently was blown with dichlorodifluoromethane (CFC 12) but is now blown with a mixture of chlorodifluoromethane (HCFC 22) and 1 -chloro-l,l-difluoroethane (HCFC 142b). 

CaO was activated by the addition of Ni (acetylacetonate)2 followed by calcining at 973 K. This resulted in the production of nickel on the carbonate matrix, and was effective in decomposing dichlorodifluoromethane (CFC-12) to CO2 at 723 K—with low amounts of CO—while the halogen was combined as CaFCl (Tamai et al. 2006). 

No information on potentially susceptible populations was located for HCFC-141b. A structurally related chemical, 1,1,1,2-tetrafluoroethane, has been tested in metered-dose inhalers for the treatment of asthma. Test subjects included adult and pediatric asthma patients as well as individuals with severe COPD. No adverse effects were reported (Smith et al. 1994 Taggart et al. 1994 Ventresca 1995 Woodcock 1995). The structurally related chemicals trichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12) are presently used in metered-dose inhalers for the treatment of asthma but are phased out under the Montreal Protocol of 1987 (Alexander 1995). Structurally related compounds including 1,1,1-trichloroethane and trichlorofluoromethane were also tested for cardiac sensitization in a dog model with experimentally induced myocardial infarction. In these experiments cardiac sensitization occurred under the same conditions as in healthy dogs (Trochimowicz et al. 1976). 

Until the late 1980s trichlorofluoromethane (CFC 11) was also used to blow flexible, open-celled polyurethane foams used in furniture upholstery however, the rapid loss of the blowing agent to the atmosphere meant that this CFC application was one of the first to be eliminated when concern over the possible effects of CFCs on stratospheric ozone increased. Similarly, dichlorodifluoromethane (CFC 12) in the relatively minor application of polystyrene hot-food containers was also rapidly replaced by hydrocarbon-blowing agents. 

Estimate the molecular diffusion coefficient of dichlorodifluoromethan (CFC-12) in water, )IW, at 25°C, by the following methods ... 

Peclet Number and Damkdhler Number Box 22.2 Alternative Definitions of the Damkdhler Number Illustrative Example 22.1 Vertical Distribution of Dichlorodifluoromethane (CFC-12) in a Small Lake... 

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