The Atmosphere Gases - PowerPoint PPT Presentation

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The Atmosphere Gases

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  1. The Atmosphere Gases Compared to the size of the Earth , the atmosphere is a thin shell. The part of the atmosphere we know best - the troposphere - is an even thinner shell, only 12 kilometers (7.5 miles) thick. It is in the troposphere that all weather occurs; it is only here that life exists. The thin atmosphere lighted by the setting Sun. Atmosphere

  2. Scientists View of Atmosphere Atmosphere

  3. Variation of Temperature in the Atmosphere temperature Atmosphere

  4. Air Composition at Sea Level ComponentVolume percent N2 78.084 O2 20.946 Ar 0.934 CO2 0.037 Ne 0.001818 He 0.000524 CH4 0.0002 Kr 0.000114 H2 0.00005 N2O 0.00005 Xe 0.000009 O3, SO2, NO2, NH3, CO, I2 . trace Have you considered the atmosphere as sources of elements and compounds? Atmosphere

  5. Water Vapor in the Atmosphere Explain these terms: Absolute humidity Partial pressure of water vaporVapor pressure of water Relative humidity = Variation of water vapor pressure Partial pressure of water vaporVapor pressure of water Discussed when we talk about gases, review please. Atmosphere

  6. H2O (g) in Pacific during El Nino, Oct. 1997 Atmosphere

  7. Thomson-Joule Effect A gas cools during expansion. The amount of cooling is proportional to the pressure difference at the throttle, and increases substantially when the starting temperature of the gas is reduced. Carl von Linde produced liquid air in 1895 using the Thomson-Joule effect. Under 1 bar air liquefies at 80 K. Simple throttling will not suffice to reach this temperature. Linde introduced "countercurrent cooling". Atmosphere

  8. Liquefaction of Gases Heat is always required to convert the liquid into its gas. Reducing pressure lowers the b.p., and cools the liquid. Liquid (high P)  Liquid (low P &T) + Vapor Compressor Evaporator Atmosphere

  9. Getting N2 from Air Distillation of liquid air separate O2 from N2. Which has a higher b.p. O2 or N2? Atmosphere

  10. Physical Properties of O2, N2 & Ar Property O2. N2. Ar Melting point (K) 54.8 63.1 83.8 Boiling point (K) 90.2 77.4 87.3 Critical temperature (K) 154.6 126.2 150.8 Enthalpy of vaporization kJ mol-1 3.41 2.79 6.5 Color of liquid blue colorless colorless Atmosphere

  11. Nitrogen Compounds Ammonia and related compounds NH3, RNH2, RR’NH, NH4+, (NH2)2CO (urea), amino acids Nitrogen oxides and related compounds N2O, (anesthetic) NO, (maintain blood pressure, thins blood vessels) N2O3, NO2, (photochemical smog, brown)  N2O4 (colorless) N2O5 Acids HNO3 HNO2 Atmosphere How are some of these prepared?

  12. Oxygen Production: Isolation from air (30 million tons) lab methods of preparation Uses manufacture of iron and steel manufacture and fabrication of metals manufacture of chemicals (oxidant) water treatment rocket fuel medicine uses petroleum refineing Atmosphere

  13. Ozone Chemistry 3 O2 (g)  2 O3 (g) H = 285 kJ O2 (g) + h v  O (g) + O (g) O3 (g) + h v  O2 (g) + O (g) O3 (g) + O 2 O2 (g) H = – 390 kJ Uses water treatment (substitute for Cl2) oxidant (more powerful than O2) waste water treatment Atmosphere

  14. Ozone in the atmosphere A major source of chlorine is Freons: CFCl3 (Freon 11), CF2Cl2 (Freon 12), C2F3Cl3 (Freon 113), C2F4Cl2 (Freon 114). Freons decompose in the troposphere. For example, CFCl3® CFCl2 + ClCF2Cl3® CF2Cl + Cl. Depletion of ozone by CFC Cl + O3® ClO + O2 O3 + h v® O + O2, ClO + O ® Cl + O2 O + O3® O2 + O2. Formation of ozone O2 + h v® O + O O2 + O ® O3 O2 + O + M ® O3 + M* Absorption of UVB by ozone O3 + h v® O + O2 O3 + O ® 2 O2 Atmosphere

  15. The Carbon Cycle Atmosphere See diagram in text and other sources

  16. Carbon Dioxides in the Atmosphere Variation of CO2 in the atmosphere Atmosphere

  17. Hydrogen Productions C (coal) + H2O (g) CO (g) + H2 (g) (water gas) CO + H2O (g) CO2 (g) + H2 (g) CH4 (g) + H2O (g) CO (g) + 3 H2 (g) (fuel) Compounds HCl NH3 (the Haber process) Metallic hydrides NaH, LiAlH4, PdHx, CaH2 Hydrogenation reactions CH3 CH3 CH3 – C = C – CH3 + H2 CH3 – C – C – CH3 H H Find applications of N2, O2, & H2 Atmosphere

  18. Self Study Guide Expect quantitative test questions in chapter 8 as in other chapters. Representative problems from Chapter 8 are: 30 – find enthalpy for NH3 + NO = N2 + H2O (balance, use Hf; soln is incomplete)36 – press of a gas containing 5e12 O3 molecules 39 – 55 L gas at 145 atm and 26o C, V = ___ at STP41 – density of 79% He and 21% O2 by volume at STP?47 – determine heat of combustion54 – stoichiometry problem56 – stoichiometry and gas problem59 – relative humidity (Chapt 8 problems)61 – partial pressure problem There is no need to memorize sources and uses of the atmospheric gases. Atmosphere