Unit 4 – The Chemistry of the Environment The Chemistry of the Atmosphere Flashcards
_____ is unique among the planets of our solar system in having an atmosphere that
is chemically active and rich in oxygen.
Earth
The ________ is a protective blanket which nurtures life on the Earth and protects it from the hostile environment of outer space.
atmosphere
However, the same__________may have triggered the chemical reactions (perhaps beneath the surface) that
eventually led to life on Earth.
UV
radiation
italicized
Primitive organisms used energy from the sun to break down
carbon dioxide (produced by volcanic activity) to obtain carbon, which they incorporated in
their own cells. The major by-product of this process, called _____________, is oxygen.
photosynthesis
Another important source of oxygen is the __________ of water vapor by UV light.
Over time, the more reactive gases such as ammonia and methane have largely disappeared,
and today our atmosphere consists mainly of oxygen and nitrogen gases.
photodecomposition
_____________, with its triple bond, is a very stable molecule. However, through
biological and industrial nitrogen fixation, the conversion of molecular nitrogen into
nitrogen compounds, atmospheric nitrogen gas is converted into nitrates.
Molecular nitrogen,
___________ is converted to nitrate salts in the soil. These nutrients are taken up by plants, which in turn
are ingested by animals.
Nitric acid
_____________ reverses nitrogen fixation to complete the cycle. For example, certain anaerobic organisms decompose animal wastes as well as dead plants and
animals to produce free molecular nitrogen from nitrates.
Denitrification
_____________ is removed through respiration
and various industrial processes (mostly combustion), which produce carbon dioxide.
Atmospheric oxygen
________________ is the major mechanism by which molecular oxygen is regenerated from
carbon dioxide and water.
Photosynthesis
bold
the layer of the atmosphere that contains about 80 percent
of the total mass of air and practically all of the atmosphere’s water vapor.
troposphere
the thinnest layer of the atmosphere (10 km), but it is where all the dramatic events of
weather—rain, lightning, hurricanes—occur.
troposphere
bold
layer which consists of nitrogen, oxygen, and
ozone.
stratosphere
serves to prevent harmful UV
rays from reaching Earth’s surface.
ozone (O3)
the concentration of ozone and other gases is low, and the temperature decreases with increasing altitude.
mesosphere
is the uppermost layer of the
atmosphere.
thermosphere or ionosphere
bold
is a substance present in greater than natural
concentration as a result of human activity that has a net detrimental effect upon its
environment or upon something of value in that environment.
pollutant
bold
__________________ ,which are not
classified as pollutants unless they have some detrimental effect, cause deviations from the normal composition of an environment.
contaminants
bold
is particularly important because it is generally the logical place to eliminate pollution.
source
bold
is anything
that is affected by the pollutant.
receptor
This increase in atmospheric CO2 may well cause general
atmospheric warming—the “________________” with potentially very serious consequences
for the global atmosphere and for life on earth.
greenhouse effect,
Though not a global threat, ___________________,
CO, can be a serious health threat because it prevents blood from transporting oxygen to
body tissues.
carbon monoxide
The most abundant hydrocarbon in the atmosphere is ____________, released from underground sources as natural gas and produced by the fermentation of organic matter.
methane CH4
bold
In the presence of NO, under
conditions of temperature inversion low humidity, and sunlight, these hydrocarbons
produce undesirable _______________- manifested by the presence of visibility-obscuring particulate matter, oxidants such as ozone, and noxious organic species such as
aldehydes.
photochemical smog
bold
____________ ranging from aggregates of a few molecules to pieces of dust readily visible
to the naked eye are commonly found in the atmosphere.
Particles
bold
Very small particles called _______________
serve as bodies for atmospheric water vapor to condense upon and are essential for the
formation of rain drops.
condensation nuclei
Colloidal-sized particles in the atmosphere are called _____________.
aerosols
Those formed by grinding up bulk matter are known as ________ aerosols, whereas
particles formed from chemical reactions of gases are ___________ aerosols;
dispersion
condensation
_________________ are in general the most harmful because they have a greater
tendency to scatter light and are the most respirable.
Smaller particles
The simplest means of particulate matter removal is __________________, a phenomenon
that occurs continuously in nature.
sedimentation
___________________ may be employed for the
removal of particles from gas streams by simply settling under the influence of gravity. These
chambers take up large amounts of space and have low collection efficiencies, particularly
for small particles.
Gravitational settling chambers
Gravitational settling of particles is enhanced by increased particle size, which occurs
spontaneously by _____________.
coagulation
_______________ of particles
less than about 0.1 μm in size is primarily responsible for their contact, enabling coagulation
to occur.
Brownian motion
bold
_________________ are effective for particle
removal. These depend upon the fact that the radius of the path of a particle in a rapidly
moving, curving air stream is larger than the path of the stream as a whole.
Inertial mechanisms
collected on a separator wall because the particles are forced outward by centrifugal force.
Devices utilizing this mode of operation are called ______________).
dry centrifugal collectors (cyclones
bold
_____________, as their name implies, consist of fabrics that allow the passage of gas
but retain particulate matter.
Fabric filters
Fabric filters are used to collect dust in bags contained in structures
called ___________.
baghouses
A ____________passes gas through a device which leads the gas stream through a
converging section, throat, and diverging section.
venturi scrubber
bold
______________________ place an electrical charge on particles upstream from a wet scrubber. Larger particles and some gaseous contaminants are
removed by scrubbing action.
Ionizing wet scrubbers
