Unit 4 – The Chemistry of the Environment The Chemistry of the Atmosphere

Question 1

_____ is unique among the planets of our solar system in having an atmosphere that
is chemically active and rich in oxygen.

Answer 1

Earth

Question 2

The ________ is a protective blanket which nurtures life on the Earth and protects it from the hostile environment of outer space.

Answer 2

atmosphere

Question 3

However, the same__________may have triggered the chemical reactions (perhaps beneath the surface) that
eventually led to life on Earth.

Answer 3

UV
radiation

Question 4

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.

Answer 4

photosynthesis

Question 5

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.

Answer 5

photodecomposition

Question 6

_____________, 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.

Answer 6

Molecular nitrogen,

Question 7

___________ is converted to nitrate salts in the soil. These nutrients are taken up by plants, which in turn
are ingested by animals.

Answer 7

Nitric acid

Question 8

_____________ 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.

Answer 8

Denitrification

Question 9

_____________ is removed through respiration
and various industrial processes (mostly combustion), which produce carbon dioxide.

Answer 9

Atmospheric oxygen

Question 10

________________ is the major mechanism by which molecular oxygen is regenerated from
carbon dioxide and water.

Answer 10

Photosynthesis

Question 11

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.

Answer 11

troposphere

Question 12

the thinnest layer of the atmosphere (10 km), but it is where all the dramatic events of
weather—rain, lightning, hurricanes—occur.

Answer 12

troposphere

Question 13

bold

layer which consists of nitrogen, oxygen, and
ozone.

Answer 13

stratosphere

Question 14

serves to prevent harmful UV
rays from reaching Earth’s surface.

Answer 14

ozone (O3)

Question 15

the concentration of ozone and other gases is low, and the temperature decreases with increasing altitude.

Answer 15

mesosphere

Question 16

is the uppermost layer of the
atmosphere.

Answer 16

thermosphere or ionosphere

Question 17

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.

Answer 17

pollutant

Question 18

bold

__________________ ,which are not
classified as pollutants unless they have some detrimental effect, cause deviations from the normal composition of an environment.

Answer 18

contaminants

Question 19

bold

is particularly important because it is generally the logical place to eliminate pollution.

Answer 19

source

Question 20

bold

is anything
that is affected by the pollutant.

Answer 20

receptor

Question 21

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.

Answer 21

greenhouse effect,

Question 22

Though not a global threat, ___________________,
CO, can be a serious health threat because it prevents blood from transporting oxygen to
body tissues.

Answer 22

carbon monoxide

Question 23

The most abundant hydrocarbon in the atmosphere is ____________, released from underground sources as natural gas and produced by the fermentation of organic matter.

Answer 23

methane CH4

Question 24

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.

Answer 24

photochemical smog

Question 25

# bold ____________ ranging from aggregates of a few molecules to pieces of dust readily visible to the naked eye are commonly found in the atmosphere.

Answer 25

Particles

Question 26

# bold Very small particles called _______________ serve as bodies for atmospheric water vapor to condense upon and are essential for the formation of rain drops.

Answer 26

condensation nuclei

Question 27

Colloidal-sized particles in the atmosphere are called _____________.

Answer 27

aerosols

Question 28

Those formed by grinding up bulk matter are known as ________ aerosols, whereas particles formed from chemical reactions of gases are ___________ aerosols;

Answer 28

dispersion condensation

Question 29

_________________ are in general the most harmful because they have a greater tendency to scatter light and are the most respirable.

Answer 29

Smaller particles

Question 30

The simplest means of particulate matter removal is __________________, a phenomenon that occurs continuously in nature.

Answer 30

sedimentation

Question 31

___________________ 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.

Answer 31

Gravitational settling chambers

Question 32

Gravitational settling of particles is enhanced by increased particle size, which occurs spontaneously by _____________.

Answer 32

coagulation

Question 33

_______________ of particles less than about 0.1 μm in size is primarily responsible for their contact, enabling coagulation to occur.

Answer 33

Brownian motion

Question 34

# 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.

Answer 34

Inertial mechanisms

Question 35

collected on a separator wall because the particles are forced outward by centrifugal force. Devices utilizing this mode of operation are called ______________).

Answer 35

dry centrifugal collectors (cyclones

Question 36

# bold _____________, as their name implies, consist of fabrics that allow the passage of gas but retain particulate matter.

Answer 36

Fabric filters

Question 37

Fabric filters are used to collect dust in bags contained in structures called ___________.

Answer 37

baghouses

Question 38

A ____________passes gas through a device which leads the gas stream through a converging section, throat, and diverging section.

Answer 38

venturi scrubber

Question 39

# bold ______________________ place an electrical charge on particles upstream from a wet scrubber. Larger particles and some gaseous contaminants are removed by scrubbing action.

Answer 39

Ionizing wet scrubbers