CHEM173s06answers2 - CHEM173 Midterm 2 Spring 2006 Name_...

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CHEM173 Midterm 2 Name_______________________ Spring 2006 UCSD ID Number______________________ 1. Chemical Families and Cycles (60 pts: 10, 10, 10, 10, 10, 10) a) What is NO x ? How does NO x differ from NO y ? 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 includes precursors and products that can be easily converted to or from NO x , such as PAN, HONO. b) What is the most important type of anthropogenic source of NO x ? Fossil fuel burning. c) What is the Nitrogen cycle? Describe its components, interfaces, and processes. The Nitrogen 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 nitrogen 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) and evaporation of NH 3 , N 2 , NO x , and wet/dry deposition of HNO 3 and NO x to the ocean and land surfaces, as well as denitrification and fixation. d) 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. 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), nitrite NO 3 - (+5) plus ammonia NH 4 + (-3), and nitrous oxide N 2 O (+1). e) Which reservoir is responsible for the removal of most of the reactive nitrogen? What is the process (or processes) responsible for this removal? Most of the reactive nitrogen is removed by wet deposition or precipitation as HNO 3 or NO 3 - . f)
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This note was uploaded on 10/28/2010 for the course CHEM 173 taught by Professor Dr.dancziczo during the Spring '10 term at UC Riverside.

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CHEM173s06answers2 - CHEM173 Midterm 2 Spring 2006 Name_...

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