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

17.1 The Nitrogen Cycle

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

17.1 The Oxygen Cycle

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

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

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

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

Concentrations of Chlorine Monoxide and Ozone Versus Latitude

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

Ozone Depletion (in purple) Over the South Pole 17.3

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 HOSO 2 (g) + O 2 (g) HO 2 (g) + SO 3 (g)

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

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

The Carbon Cycle

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

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

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

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

17.6

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

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

17.8 U x 10 9 yr Th days Pa min U x 10 5 yr Th x 10 4 yr Ra x 10 3 yr Rn d