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Unformatted text preview: Chapter 10: Gases and the Atmosphere 480 95. Answer/Explanation: CF 4 has no CCl bonds, which in CCl 4 are readily broken when exposed to UV light. Looking at the bond enthalpies, CCl (327 kJ/mol) is much weaker than CF (486 kJ/mol). In fact, the bond enthalpy of CF is very close to the bond enthalpy of O=O (498 kJ/mol)! 96 . Answer/Explanation: CH 3 F has no CCl bonds, which in CH 3 Cl are readily broken when exposed to UV light. Looking at the bond enthalpies, CCl (327 kJ/mol) is much weaker than CF (486 kJ/mol). In fact, the bond enthalpy of CF is very close to the bond enthalpy of O=O (498 kJ/mol)! 97. Answer: FCCl 3 , F 2 CCl 2 , F 3 CCl Strategy and Explanation: CFCs must have at least one F and one Cl atom. They must also have four halogens (either F or Cl) attached to the C atom. The set of possible variations are: FCCl 3 , F 2 CCl 2 , F 3 CCl 98 . Answer/Explanation: CFCs are not toxic. Refrigerants used before CFCs were very dangerous. One example is NH 3 , a strong-smelling, reactive chemical. In any web browser, type the keywords CFCs or refrigerants and you will get a plethora of hits. 99. Answer/Explanation: New CFCs cannot catalyze the destruction of ozone at night, because sunlight is required to initiate the first step and create the Cl radical. However, additional reactions recreate the Cl, which can continue to destroy ozone even at night. 100. Answer/Explanation: Ozone is formed from the reaction of oxygen and a free radical oxygen atom as shown in this equation. O + O 2 O 3 Sunlight is not required for this reaction to occur. Chemistry and Pollution in the Troposphere 101 . Answer: Primary pollutants (e.g., particle pollutants, including aerosols and particulates; sulfur dioxide; nitrogen oxides; hydrocarbons) secondary pollutants (e.g., ozone). (see Section 10.12) Strategy and Explanation: Primary pollutants are substances that are introduced into the air directly from their source. Particle pollutants: pollutants made out of particles: aerosols: particles incorporated into water droplets. particulates: larger solid particles Sulfur dioxide: pollutant produced when sulfur or sulfur compounds are burned in air. Nitrogen oxides: pollutant produced when nitrogen and oxygen react at high temperatures. Hydrocarbons: pollutants produced from many organic sources; their identity is small hydrocarbons from CH 4 to ones with six or seven carbons. Secondary pollutants are substances produced from reactions of a primary pollutants. Ozone: ozone in the troposphere is produced from a reaction of O 2 with O 2 in the presence of intense energy (e.g., spark, lightening, etc.) Sulfur trioxide: SO 3 is produced from the reaction of SO 2 ....
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- Spring '08