CHEM173 Midterm 2
UCSD ID Number______________________
Chemical Families and Cycles (60 pts: 10, 10, 10, 10, 10, 10)
What is NO
How does NO
differ from NO
is the chemical family consisting of nitrogen oxides NO, NO
Mostly NO and NO
is okay too.
includes precursors and products that can be easily converted to or from NO
such as PAN, HONO.
What is the most important type of anthropogenic source of NO
Fossil fuel burning.
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).
interfaces across which nitrogen is transferred are the ocean-atmosphere and the biosphere-
The processes that control these transfers include combustion
emissions (fossil fuel and biomass, anthropogenic and natural) and evaporation of NH
and wet/dry deposition of HNO
to the ocean and land surfaces, as well as
denitrification and fixation.
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
(0), nitric oxide NO (+2) plus
nitrogen dioxide NO
(+4) plus nitrogen trioxide NO
(+6), nitrite NO
(+5) plus ammonia NH
(-3), and nitrous oxide N
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