1. Chemistry in the Atmosphere Chapter 17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 17.1 The Nitrogen Cycle

3. Atmospheric Nitrogen Fixation 2NO (g) + O 2 (g) 2NO 2 (g) 2NO 2 (g) + H 2 O (g) HNO 2 (aq) + HNO 3 (aq) Industrial Nitrogen Fixation N 2 (g) + 3H 2 (g) 2NH 3 (g) catalyst N 2 (g) + O 2 (g) 2NO (g) electrical energy 17.1 NH 3 + 2O 2 HNO 3 + H 2 O NH 3 + HNO 3 NH 4 NO 3 CH 4 + 2H 2 O 4H 2 + CO 2

4. 17.1 The Oxygen Cycle

5. 17.1 h + N 2 2N h + N N + e - h + O 2 O 2 + + e -

6. e-e- p+p+ + O O * + e - O * O + h + N 2 N 2 * + p + + e - + + N 2 * N 2 + h + green and red blue and violet O + NO NO 2 * NO 2 * NO 2 + h Glowing tail section of space shuttle orange 17.2 Chemical Rxs in the Thermosphere

7. Depletion of Ozone in the Stratosphere 17.3 UV O 2 O + O < 240 nm O + O 2 + M O 3 + M O 3 production O 3 destruction O 3 O + O 2 UV O + O 3 2O 2 dynamic equilibrium constant concentration of O 3 in stratosphere UV Ozone Layer

8. Depletion of Ozone in the Stratosphere Anthropogenic O 3 destruction CFCl 3 CFCl 2 + Cl UV CF 2 Cl 2 CF 2 Cl + Cl UV Cl + O 3 ClO + O 2 ClO + O Cl + O 2 + O 3 + O 2O 2 Cl catalyzes the reaction 17.3

9. Concentrations of Chlorine Monoxide and Ozone Versus Latitude

10. Polar stratospheric clouds provide a surface for the rx: Cl 2 + h 2Cl Spring sunlight HCl + ClONO 2 Cl 2 + HNO 3 17.3 Cl + O 3 ClO + O 2 ClO + O Cl + O 2 + O 3 + O 2O 2

11. Ozone Depletion (in purple) Over the South Pole 17.3

12. 2H 2 S (g) + 3O 2 (g) 2SO 2 (g) + 2H 2 O (g) SO 2 (g) + OH (g) HOSO 2 (g) SO 3 (g) + H 2 O (g) H 2 SO 4 (g) H 2 SO 4 aerosols have a local cooling effect on the atmosphere. 17.4 HOSO 2 (g) + O 2 (g) HO 2 (g) + SO 3 (g)

13. The trapping of heat near Earth’s surface by gases in the atmosphere is the greenhouse effect. 17.5 H 2 O + h H 2 O * CO 2 + h CO 2 *

14. Why don’t N 2 and O 2 contribute to the greenhouse effect ? N 2 and O 2 cannot absorb IR radiation. 3 vibration modes of H 2 O 2 of the vibration modes of CO 2 17.5

15. The Carbon Cycle

16. 17.5 The Yearly Variation in the CO 2 Concentration At Mauna Loa, Hawaii

17. 17.5 The Temperature Rise on Earth’s Surface from 1880 to 1996

18. Mean precipitation pH in 1994 SO 2 (g) + OH (g) HOSO 2 (g) SO 3 (g) + H 2 O (g) H 2 SO 4 (g) HOSO 2 (g) + O 2 (g) HO 2 (g) + SO 3 (g) Acid Rain 17.6

19. CaCO 3 (s) + H 2 SO 4 (aq) CaSO 4 (s) + H 2 O (l) + CO 2 (g) 2CaCO 3 (s) + 2SO 2 (g) + O 2 (g) 2CaSO 4 (s) + CO 2 (g) 17.6 The Effect of Acid Rain on the Marble Statue of George Washington (New York, City). Photos Taken in 1944 and 1994

20. 17.6

21. 17.7 Photochemical smog is formed by the reactions of automobile exhaust in the presence of sunlight. Primary pollutants: NO, CO and unburned hydrocarbons Secondary pollutants: NO 2 and O 3 N 2 (g) + O 2 (g) 2NO (g) 2NO (g) + O 2 (g) 2NO 2 (g) NO 2 (g) + h NO (g) + O (g) O (g) + O 2 (g) + M O 3 (g) + M

22. 17.7 Typical Variations with Time in the Concentration of Air Pollutants on a Smoggy Day

23. 17.8 U 238 92 4.51 x 10 9 yr Th 234 90 24.1 days Pa 234 91 1.17 min U 234 92 2.47 x 10 5 yr Th 230 90 7.5 x 10 4 yr Ra 226 88 1.6 x 10 3 yr Rn 222 86 3.82 d