Compressed gases hydrocarbon families

A few hydrocarbon derivatives from the alkyl-halide family are 2.2 nonflammable compressed gases. This illustrates the wide range of hazards of the alkyl halides as a group. Some are flammable, some are toxic, and some are nonflammable and nontoxic. They can still act as asphyxiants and displace the oxygen in the air. It is important to remember that the primary hazard of the alkyl halides is toxicity. Some of them are also flammable therefore, all must be assumed to be toxic and flammable until the individual chemical is researched and the actual hazards are determined. It is interesting to note that while the DOT lists tetrafluoromethane as a nonflammable, nonpoisonous gas, the Condensed Chemical Dictionary lists the compound as toxic by inhalation. The NIOSH Pocket Guide to Chemical Hazards does not list the compound. The best source of information about this compound and others may be the MSDS (material safety data sheet). Examples of nonflammable Class 2.2 alkyl halides are tetrafluoromethane and trifluoromethane. 

In vehicles, the combustion of H2 rather than a hydrocarbon-based fuel reduces both CO2 emissions and a dependence on fossil fuels, (a) Using data from Appendix 12, show that the combustion of H2 releases 120 kJ (b) The chart in Box 10.2 shows that the stored energy per unit mass of compressed (at 35 MPa) H2 gas and of liquid H2 are the same, but that liquid H2 stores more energy per unit volume than compressed H2. Rationalize these data, (c) 3 kg of gasoline (petrol) is equivalent to 1 kg of H2 in terms of stored energy. Comment on this fact in terms of the practical application of H2 as a fuel in a family saloon car. 

Fluids in the hydrocarbon group represent the bulk of pipeline utilization, with natural gas being the predominant user within that family. The increased use of carbon dioxide for oil field stimulation has created a dramatic growth in pipeline construction for that commodity. Other compressed gases distributed by pipeline include ammonia, chlorine, nitrogen, and oxygen. 

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