ECHEM Chapter 9 – Flashcards

question
What happens to the mean free path at high altitudes?
answer
Becomes larger
question
Describe the Troposhere
answer
0 to 10 or 16 km
top layer water freezes at -56C
normal lapse rate
question
Describe Stratosphere
answer
Troposphere to 50km
Inverse lapse time
Max [O3] ~10ppm
Max temp -2c
absorbs UV radiation
question
Define normal lapse time
answer
temp decreases with increase in altitude
question
Define inverse lapse time
answer

temperature increases with increase in altitude

observed in the stratosphere

question
What is the relationship of increasing altitude and atmospheric pressure?
answer
Atmospheric pressure decreases logrithmicly
question
Describe the mesosphere
answer
50 to 85km
normal lapse time
lacks radiation absorbing species
min temp -92C
question
Describe Thermosphere
answer

85 to ~500km

temperature varied

Max temp 1200C

Absorption of highly energetic radiation(UV<100nm,x-ray,cosmic rays)

question
Define Ionosphere
answer
50km and up
question
What is Earth's heating balance?
answer
1.34x103 watts/m2 hits the thermosphere only half reaches Earth's surface
question
Define mantle heating
answer
convection and conduction from Earth's mantle. equivalent to 1% of solar heating
question
What are the three energy transport mechanisms?
answer
1)Conduction
2)Convection
3)Radiation
question
Define conduction
answer
Interaction of adjacent atoms
question
Define convection
answer
movement of whole masses
question
Define Radiation energy transport mechanism
answer

Electromagnetic radiation

E/M radiation only means of energy transport in vacuum.

 

question
What does the Earth have to do to all forms of energy in order to cool the planet?
answer
Convert it to electromagnetic radiation
question
What is the average e/m energy that reaches the planet?
answer
~500nm (Green Visible light)
question
What is the average e/m energy given off by the planet?
answer
~10,000 nm (Far IR)
question
What is the green house effect approx equal to?
answer
[CO2]
question
What happens to outgoing IR due to water vapor and CO2?
answer
It is absorbed and re-radiated with 1/2 going back to the planet resulting in a temp inc.
question
What happens to UV-Vis and IR due to greenhouse gases?
answer
Transparent to uv-vis and absorbs IR.
question
What is the chemical rxn for anaerobic respiration?
answer
2{CH20}-;CH4 +CO2
question
What is the chemical rxn for aerobic respiration?
answer
{CH2O}+O2-;CO2+H2O
question
What is the chemical reaction for photosynthesis?
answer
CO2+H2O+hv-;{CH2O}+H2O
question
What is the chemical reaction for combustion?
answer

C+O2-;CO2 

 

question
What are the experimental parameters of a photochemical reaction?
answer
1) Very low concentration of species
2) Very high pressure
3) High energy Radiation
4) No third bodies (No container walls)
question
What are the seven relaxation mechanisms?
answer
1) Physical quenching
2) Dissociation
3) Direct reaction
4) Luminescence
5) Intermolecular energy transfer
6) Intramolecular Transfer
7) Photoionization
question
Define Physical quenching
answer

Loss of energy to another molecule

O2*+M-;O2+M(increased translational energy

This process is followed by dissipation of energy as heat

question
Define Dissociation
answer
Excite an electron in a bonding MO to a non bonding MO
O2*->O+O
question
Define Direct reaction
answer
Excite molecule reacts directly with another molecule O2*+O3-;2O2+O
question
Define Luminesence
answer

Excited species returns to ground state and gives of light

NO2*-;NO2+hv

The emitting wavelength is equal or lesser an energy than what cause the initial excitation

question
Define Intermolecular energy transfer
answer

Efficient energy transfer into a quantum state of another molecule(third body) which then becomes excited

O2*+M-;O2+M*

question
Define Intramolecular Transfer
answer
Transfer in which an excited species transfers energy with in the molecule
X*Y->XY*
question
Define Photoionization
answer

Excited molecule ejects an electron, occurs in ionosphere(50km and up)

N2*-;(N2+) + e-

question
Where do ions exist in the atmosphere?
answer
In the upper atmosphere 50km and up
question
What are the significant species found in the ionosphere?
answer
Cations and anions
question
What is the most abundant anion in the ionosphere?
answer
electron
question
Describe how SKIP occurs.
answer
Through photoionization, you get reflection of radiowaves if the particles formed are the same wavelength apart as the radiowave. During the day the ionosphere is made through photoionization and night it lifts. The reason for the lifting is because the particles are no longer being made and particles at lower elevation react more rapidly because of their shorter mean free path.
question
What is the mean free path at sea level?
answer
1x10-6 cm
question
What is the mean free path at 500km
answer
1x106 cm
question
Describe the Santa Anna winds
answer
Electron rich winds that are formed by the friction of the winds stripping electrons from dried brush
question
What is an example of Ions in the troposphere?
answer
Santa Anna Winds
question
What are characteristics of free radicals?
answer
1) Atoms with unpaired electrons
2) Formed by energetic radiation
3) highly reactive
4) Stable (relating to high mean free path)
question
How would you compare excited atoms to free radicals?
answer
1) Excited atoms have many ways to relax and don't require a collision
2) Free radicals are dependent on mean free path and have to react with a third body. (Life time increased with increase in mean free path)
question
Define ozone:
answer
Molecule with a protective function of absorbing UV in the Stratosphere
question
Where is good ozone found:
answer
Stratosphere
question
Where is bad ozone found?
answer
Troposphere
question
How is ozone produced? Two step process
answer

1) O3+hv(242nm) -> O+O2

2)O+O2+M->O3+M(increased energy)

question
Why is ozone depletion in the stratosphere a concern?
answer
Ozone production is very slow because of the long mean free path and the unlikelihood of O + O2 + a third body colliding simultaniously
question
What are the negative effects of ozone in the troposphere?
answer

1) Toxic, bind irreversibly to cytochrome c

2) Causes labored breathing and eye irritation

3) Oxidizing agent

4) damages materials

question
Describe CO2 in the atmosphere
answer

1) Minor constituent 0.035% or 350ppm

2) Like water vapor, CO2 absorbs IR

3) [CO2] rising ~1ppm/yr

4) Estimated increase in global temperature due to CO2 in 2050 is 1.5-4.5C

question
What are seasonal trends of CO2?
answer
1)Increased [C02] in fall/winter when photosynthesis is low and degredation is higher
2)Decreased [CO2] in summer when photosynthesis is at its peak.
question
What is the phenomenon responsible for the temperature maximum at the boundary of the stratosphere and mesosphere?
answer
Due to the presence of O3 and the heating effect caused by the absorption of UV Followed by radiation and relaxation
question
What function does a third body serve in an atmospheric chemical reaction?
answer
Third bodies absorb excess energy when the molecules form, stabilizing the newly formed molecule
question
Why does the lower boundary of the ionosphere lift at night?
answer
In darkness, positive ions created by UV light recombine with free electrons in the lower regions of the ionosphere, the process is rapid at high molecular concentrations, causing the lower limit of the ionosphere to lift at night
question
Considering the total number of electrons in NO2, why might it be expected that the reaction of a free radical with NO2 is a chain terminating reaction?
answer

NO2 is chain terminating because,

1) NO2 is a stable free radical present at high concentrations and

2) the odd number of electrons make it chain terminating

question
Of the species O, HO•*, NO2*, H3C•, and N+, which could most readily revert to a non reactive "normal" species in total isolation?
answer
NO2*, Excited species have a finite lifetime because they can lose energy through radiation w/o having to react with other species.
question
What is the desinction between the symbols * and • in discussing chemically active species in the atmosphere?
answer
* means the molecule is in an excited electronic state
• means free radical or molecular fragment with unshared electrons
question
What two chemical species are most generally responsible for the removal of hydroxy radicals from the unpolluted troposphere?
answer
Methane and carbon monoxide
question
Describe oxygen exchange among the atmosphere, geosphere, hydrosphere, and biosphere
answer

1) oxygen consumed by reducing gases of volcanoes 2CO+O2->CO2

2)Oxygen consumed by burning of fossil fuels C+O2->CO2

3)Oxidative weathering of reduced minerals O2+4FeO->2Fe2O3

4)Respiration of plants and animals 5)Photosynthesis

6)Combined oxygen held in sediments Ca2+CO32-->CaCO3

7)Ozone shield absoption of UV radiation from 220-330nm

1)O3+hv->O+O2

2)O2+hv-> O+O

3)O+O2+M->O3+M(increased energy)

question
How far does high energy wavelength (<100nm) penetrate?
answer
to approximately an altitude of 200km
question
How far does UV radiation (200-300nm) penetrate?
answer
to approximately an altitude of 50km
question
How far does radiation (wavelength > 330nm) penetrate?
answer
All the way through to the Earth's surface
question
Composition of the atmosphere
answer
78.08% nitrogen
20.95% oxygen
0.934% argon
0.035% CO2
0.005% Noble gases
Varied water content 0.1% to 5.0%
question
What ultimately happens to the energy absorbed as IR radiation?
answer
Dissipated as heat and raises the temperature of the whole atmosphere.
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question
What happens to the mean free path at high altitudes?
answer
Becomes larger
question
Describe the Troposhere
answer
0 to 10 or 16 km
top layer water freezes at -56C
normal lapse rate
question
Describe Stratosphere
answer
Troposphere to 50km
Inverse lapse time
Max [O3] ~10ppm
Max temp -2c
absorbs UV radiation
question
Define normal lapse time
answer
temp decreases with increase in altitude
question
Define inverse lapse time
answer

temperature increases with increase in altitude

observed in the stratosphere

question
What is the relationship of increasing altitude and atmospheric pressure?
answer
Atmospheric pressure decreases logrithmicly
question
Describe the mesosphere
answer
50 to 85km
normal lapse time
lacks radiation absorbing species
min temp -92C
question
Describe Thermosphere
answer

85 to ~500km

temperature varied

Max temp 1200C

Absorption of highly energetic radiation(UV<100nm,x-ray,cosmic rays)

question
Define Ionosphere
answer
50km and up
question
What is Earth's heating balance?
answer
1.34x103 watts/m2 hits the thermosphere only half reaches Earth's surface
question
Define mantle heating
answer
convection and conduction from Earth's mantle. equivalent to 1% of solar heating
question
What are the three energy transport mechanisms?
answer
1)Conduction
2)Convection
3)Radiation
question
Define conduction
answer
Interaction of adjacent atoms
question
Define convection
answer
movement of whole masses
question
Define Radiation energy transport mechanism
answer

Electromagnetic radiation

E/M radiation only means of energy transport in vacuum.

 

question
What does the Earth have to do to all forms of energy in order to cool the planet?
answer
Convert it to electromagnetic radiation
question
What is the average e/m energy that reaches the planet?
answer
~500nm (Green Visible light)
question
What is the average e/m energy given off by the planet?
answer
~10,000 nm (Far IR)
question
What is the green house effect approx equal to?
answer
[CO2]
question
What happens to outgoing IR due to water vapor and CO2?
answer
It is absorbed and re-radiated with 1/2 going back to the planet resulting in a temp inc.
question
What happens to UV-Vis and IR due to greenhouse gases?
answer
Transparent to uv-vis and absorbs IR.
question
What is the chemical rxn for anaerobic respiration?
answer
2{CH20}-;CH4 +CO2
question
What is the chemical rxn for aerobic respiration?
answer
{CH2O}+O2-;CO2+H2O
question
What is the chemical reaction for photosynthesis?
answer
CO2+H2O+hv-;{CH2O}+H2O
question
What is the chemical reaction for combustion?
answer

C+O2-;CO2 

 

question
What are the experimental parameters of a photochemical reaction?
answer
1) Very low concentration of species
2) Very high pressure
3) High energy Radiation
4) No third bodies (No container walls)
question
What are the seven relaxation mechanisms?
answer
1) Physical quenching
2) Dissociation
3) Direct reaction
4) Luminescence
5) Intermolecular energy transfer
6) Intramolecular Transfer
7) Photoionization
question
Define Physical quenching
answer

Loss of energy to another molecule

O2*+M-;O2+M(increased translational energy

This process is followed by dissipation of energy as heat

question
Define Dissociation
answer
Excite an electron in a bonding MO to a non bonding MO
O2*->O+O
question
Define Direct reaction
answer
Excite molecule reacts directly with another molecule O2*+O3-;2O2+O
question
Define Luminesence
answer

Excited species returns to ground state and gives of light

NO2*-;NO2+hv

The emitting wavelength is equal or lesser an energy than what cause the initial excitation

question
Define Intermolecular energy transfer
answer

Efficient energy transfer into a quantum state of another molecule(third body) which then becomes excited

O2*+M-;O2+M*

question
Define Intramolecular Transfer
answer
Transfer in which an excited species transfers energy with in the molecule
X*Y->XY*
question
Define Photoionization
answer

Excited molecule ejects an electron, occurs in ionosphere(50km and up)

N2*-;(N2+) + e-

question
Where do ions exist in the atmosphere?
answer
In the upper atmosphere 50km and up
question
What are the significant species found in the ionosphere?
answer
Cations and anions
question
What is the most abundant anion in the ionosphere?
answer
electron
question
Describe how SKIP occurs.
answer
Through photoionization, you get reflection of radiowaves if the particles formed are the same wavelength apart as the radiowave. During the day the ionosphere is made through photoionization and night it lifts. The reason for the lifting is because the particles are no longer being made and particles at lower elevation react more rapidly because of their shorter mean free path.
question
What is the mean free path at sea level?
answer
1x10-6 cm
question
What is the mean free path at 500km
answer
1x106 cm
question
Describe the Santa Anna winds
answer
Electron rich winds that are formed by the friction of the winds stripping electrons from dried brush
question
What is an example of Ions in the troposphere?
answer
Santa Anna Winds
question
What are characteristics of free radicals?
answer
1) Atoms with unpaired electrons
2) Formed by energetic radiation
3) highly reactive
4) Stable (relating to high mean free path)
question
How would you compare excited atoms to free radicals?
answer
1) Excited atoms have many ways to relax and don't require a collision
2) Free radicals are dependent on mean free path and have to react with a third body. (Life time increased with increase in mean free path)
question
Define ozone:
answer
Molecule with a protective function of absorbing UV in the Stratosphere
question
Where is good ozone found:
answer
Stratosphere
question
Where is bad ozone found?
answer
Troposphere
question
How is ozone produced? Two step process
answer

1) O3+hv(242nm) -> O+O2

2)O+O2+M->O3+M(increased energy)

question
Why is ozone depletion in the stratosphere a concern?
answer
Ozone production is very slow because of the long mean free path and the unlikelihood of O + O2 + a third body colliding simultaniously
question
What are the negative effects of ozone in the troposphere?
answer

1) Toxic, bind irreversibly to cytochrome c

2) Causes labored breathing and eye irritation

3) Oxidizing agent

4) damages materials

question
Describe CO2 in the atmosphere
answer

1) Minor constituent 0.035% or 350ppm

2) Like water vapor, CO2 absorbs IR

3) [CO2] rising ~1ppm/yr

4) Estimated increase in global temperature due to CO2 in 2050 is 1.5-4.5C

question
What are seasonal trends of CO2?
answer
1)Increased [C02] in fall/winter when photosynthesis is low and degredation is higher
2)Decreased [CO2] in summer when photosynthesis is at its peak.
question
What is the phenomenon responsible for the temperature maximum at the boundary of the stratosphere and mesosphere?
answer
Due to the presence of O3 and the heating effect caused by the absorption of UV Followed by radiation and relaxation
question
What function does a third body serve in an atmospheric chemical reaction?
answer
Third bodies absorb excess energy when the molecules form, stabilizing the newly formed molecule
question
Why does the lower boundary of the ionosphere lift at night?
answer
In darkness, positive ions created by UV light recombine with free electrons in the lower regions of the ionosphere, the process is rapid at high molecular concentrations, causing the lower limit of the ionosphere to lift at night
question
Considering the total number of electrons in NO2, why might it be expected that the reaction of a free radical with NO2 is a chain terminating reaction?
answer

NO2 is chain terminating because,

1) NO2 is a stable free radical present at high concentrations and

2) the odd number of electrons make it chain terminating

question
Of the species O, HO•*, NO2*, H3C•, and N+, which could most readily revert to a non reactive "normal" species in total isolation?
answer
NO2*, Excited species have a finite lifetime because they can lose energy through radiation w/o having to react with other species.
question
What is the desinction between the symbols * and • in discussing chemically active species in the atmosphere?
answer
* means the molecule is in an excited electronic state
• means free radical or molecular fragment with unshared electrons
question
What two chemical species are most generally responsible for the removal of hydroxy radicals from the unpolluted troposphere?
answer
Methane and carbon monoxide
question
Describe oxygen exchange among the atmosphere, geosphere, hydrosphere, and biosphere
answer

1) oxygen consumed by reducing gases of volcanoes 2CO+O2->CO2

2)Oxygen consumed by burning of fossil fuels C+O2->CO2

3)Oxidative weathering of reduced minerals O2+4FeO->2Fe2O3

4)Respiration of plants and animals 5)Photosynthesis

6)Combined oxygen held in sediments Ca2+CO32-->CaCO3

7)Ozone shield absoption of UV radiation from 220-330nm

1)O3+hv->O+O2

2)O2+hv-> O+O

3)O+O2+M->O3+M(increased energy)

question
How far does high energy wavelength (<100nm) penetrate?
answer
to approximately an altitude of 200km
question
How far does UV radiation (200-300nm) penetrate?
answer
to approximately an altitude of 50km
question
How far does radiation (wavelength > 330nm) penetrate?
answer
All the way through to the Earth's surface
question
Composition of the atmosphere
answer
78.08% nitrogen
20.95% oxygen
0.934% argon
0.035% CO2
0.005% Noble gases
Varied water content 0.1% to 5.0%
question
What ultimately happens to the energy absorbed as IR radiation?
answer
Dissipated as heat and raises the temperature of the whole atmosphere.
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