Chapter 12 Atomsphere

Atmosphere What gas make up the atmosphere? –Nitrogen 78.08% –Oxygen20.95% –Argon0.934% –Water0.05% or less –Carbon Dioxide0.034% –Neon, Helium, Methane, Krypton <0.002% –Hydrogen, Xeon, Sulfur Dioxide, Ozone, Nitrogen Dioxide, Ammonia, Iodine, Carbon Monoxide

Air Pollution What is air pollution? –Substances in the atmosphere that have harmful effect on the environment Is all air pollution man-made? Natural Sources of Pollution –Volcanos –Forest Fires –Plants –Oceans

Air Pollution Why is air pollution a concern today?

Air Pollution Why is air pollution a concern today? –Modern Society and Energy Demands What are the Harmful Effects? –Acid Rain –Ozone Depletion –Greenhouse Effect –Smog

Ozone What is Ozone? –allotrope of oxygen, O 3 –pale blue gas –very reactive, strong oxidizer Allotrope –different molecular forms of the same element How is Ozone formed?

Ozone Formation

Ozone is form from high energy reaction –lighting in atmosphere Ozone is naturally occurring in upper stratosphere Ozone absorbs harmful UVB radiation from the sun

Ozone Depletion How is the Ozone depleted? –Chlorofluorocarbons, CFCs CFCs react with sunlight to form free Cl radicals Cl + O 3  ClO + O 2 ClO + O  Cl + O 2

Ozone Depletion CFCs have been replaced by hydrocarbons due to the 1990 Clean Air Act –propane –butane –isobutane –isopentane Used to blow Styrofoam and as a propellant for aerosols, like shave gel and hair spray

Greenhouse Effect The earth atmosphere acts as a greenhouse –lets in sunlight and energy and insolates

Greenhouse Effect The earth atmosphere acts as a greenhouse –lets in sunlight and energy and insolates Greenhouse gases –Carbon dioxide –Methane –Water –CFCs –Other Hydrocarbons

Greenhouse Effect Greenhouse gases absorb IR radiation –radiation absorbed by the bonds –bonds stretch and vibrate faster

Greenhouse Effect Greenhouse gases cause global warming –no one know for sure the long term effects How much will the temperature increase? How much of the polar ice will melt? How high will the ocean rise? What will be the effect on weather and climate?

Smog What is Smog? –combination of water vapor and pollutants –condensation of water into fine mist Modern Smog (Photochemical Smog) –results from the emissions of the combustion of fossil fuels –unburned hydrocarbons and nitrogen monoxide

Photochemical Smog these reaction set-up complex reaction that form hydroxyl radicals and compounds that cause photochemical smog 2 NO + O 2  2 NO 2 NO 2 + light  NO + O O 2 + O  O 3

Photochemical Smog PAN compounds like PAN are eye irritants and damage lung tissue and plants these compounds allow for the condensation of water, which makes the problem worst