Midterm2 Sp07

Midterm2 Sp07 - CHEM173 Midterm 2 Spring 2007 Name_ UCSD ID...

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Name_______________________ Spring 2007 UCSD ID Number______________________ 1. Chemical Families and Cycles (60 pts: 10, 10, 10, 10, 10, 10) a) What is NO x ? What is the name for the chemical family that includes precursors and products that can be easily converted to or from NO x ? b) Name the main atmospheric reservoirs of nitrogen. For each reservoir, name the chemical compound, write its chemical formula, and identify the oxidation state of nitrogen. c) What is the Sulfur cycle? Describe its components, interfaces, and processes. d) What is the most important type of anthropogenic source of SO x ? e) Which reservoir is responsible for the removal of most of the reactive sulfur? What is the process (or processes) responsible for this removal? f) If the atmosphere contains 0.3 Tg(S) of SO 2 and the total removal rate is 120 Tg(S) per year, what is the residence time of SO 2 in the troposphere? a) NO x is the chemical family consisting of nitrogen oxides NO, NO 2 and NO 3 . Mostly NO and NO 2 is okay too. NO y is the chemical family that includes precursors and products that can be easily converted to or from NO x , such as PAN, HONO. b) The four atmospheric reservoirs of nitrogen are nitrogen N 2 (0), nitric oxide NO (+2) plus nitrogen dioxide NO 2 (+4) plus nitrogen trioxide NO 3 (+6), nitrate NO 3 - (+5) plus ammonia NH 4 + (-3), and nitrous oxide N 2 O (+1). c) The Sulfur cycle is the pathways by which and reservoirs through which compounds of nitrogen are transferred among the atmosphere, the hydrosphere (including the oceans), the biosphere (including plants), the cryosphere, and the geosphere (including soil). The primary interfaces across which sulfur is transferred are the ocean-atmosphere and the biosphere- atmosphere interfaces. The processes that control these transfers include combustion emissions (fossil fuel and biomass, anthropogenic and natural) of SO 2 , volcanic emissions of SO 4 2- and SO 2, soil emissions of H 2 S and COS, and algae production of DMS and CS 2 , and wet/dry deposition of SO 4 2- and SO 2 to the ocean and land surfaces, as well as in situ transformations. d) Fossil fuel burning.
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Midterm2 Sp07 - CHEM173 Midterm 2 Spring 2007 Name_ UCSD ID...

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