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Environmental Chemistry > Quiz 4 > Flashcards

Quiz 4 Flashcards

1
Q

To produce the Dioxin, Cl must be in what position next to the O?

A

alpha position

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2
Q

Toxicity of Dioxin

A

Most toxic

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3
Q

Toxicity of Dioxin

A

Least toxic

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4
Q

What is the requirmen for a phenoxide ion to form a dioxine?

A

A lot of heat and the Cl atom next to the O atom such as in Agent Orange

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5
Q

Residence Time calculation:

Runoff supplies 2.0 ppm of a particular pesticide to a lake each year. The concentration of the pesticide in the lake is 6.0 ppm. What is the average residence time of the pesticide in the lake?

A

6.0 ppm/2.0 ppm/yr=3.0 yr

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6
Q

Half Life Calculation:

A lake is contaminated with a radioactive isotope at 400 ppm. The radio active isotope has a half life of 5 year. What is the concentration of the radioactive isotope in the lake after 4 half lives?

A

1 half life 400->200
2 half lives 200->100
3 half lives 100->50
4 half lives 50->25

Answer: 25 ppm

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7
Q

Steady State Concentration Calculation:

Hg2+ (aq) has a half life of 6.0 days. A person consumes fish at a constant rate for 3 years. If a person consumes 1.0 mg of Hg2+(aq)/day what concentration steady state of Hg2+(aq) will they obtain?

A

CSS=1.45 X 1.0 mg Hg2+(aq) / day X 6.0 days = 9.0 mg Hg2+(aq)

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8
Q

Toxicity of Metals and Speciation:

Not Toxic

A

Hg (l)
Pb (s)
Cd (s)
As (s)

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9
Q

Toxicity of Metals and Speciation:

Toxic

A

Hg (g)

Metals as cations
Hg2+(aq), Pb2+(aq), Cd2+(aq), and As3+(aq)

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10
Q

Toxicity of Metals and Speciation:

Most Toxic

A

Metals bound to small organics i.e. CH3HgCH3

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11
Q

Spacial distribution of ozone in the Arctic

A

~450-550 DU

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12
Q

Spacial distribution of ozone in the temperate

A

~300-375 DU

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13
Q

Spacial distribution of ozone in the tropics

A

~225-250 DU

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14
Q

Spacial distribution in the ozone hole

A

~150 DU

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15
Q

1 Dobson Unit DU is equivalent to how many cm?

A

0.001

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16
Q

1 Dobson Unit DU is equivalent to how many mm?

A

0.01

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17
Q

UV light range for UVA

A

320-420 nm

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18
Q

UV light range for UVB

A

280-320 nm

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19
Q

UV light range for UVC

A

200-280 nm

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20
Q

How much UV is removed by O2

A

Most of UVC

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21
Q

How much UV is removed by O3

A

All of UVC and most of UVB

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22
Q

How much UV makes it to earth

A

All of UVA and some of UVB

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23
Q

Regions of the Atmosphere: Stratosphere

A

Temp increases with increasing altitude (-56 to -2 Celsius)
Stratified
Rxn 2 &3 related to O3 are exothermic and cause temp trend
Altitude 16-50 km

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24
Q

Regions of the Atmosphere: Tropopause

A

Where temp vs altitude trend changes
-56 Celsius
Altitude 10-15 km

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25
Regions of the Atmosphere: Troposphere
Temp decreases with increasing altitude Well mixed except H2O IR from surface of earth releases heat 25 to -56 Celsius Altitude 0-9 km
26
Regions of the Stratosphere: Upper
Very thin air Few molecules High UV light intensity Main form of the element oxygen is O No O2 for rxn 2 therefore no O3 is produced Most likely fate of O is to hit another O rxn 3
27
Regions of the Stratosphere: Mid
This air but denser than upper Less intense UV but still some Main form of oxygen is O2 Most likely fate of O is to hit an O2 molecule Rxn 2 happens in this zone so it is the max zone of O3 producation
28
Regions of the stratosphere: Lower
Air more dense No UVC needed to produce O via O2->O+O No O No O2+O->O3 No O3 formation
29
Mechanism I
Step I: X+O3--->OX+O2 Step II: OX+O--->X+O2 Net Rxn: O3+O--->2O2
30
Mechanism II
Step I: O3+X--->OX+O2 Step II: O3+X--->OX+O2 Step III: OX+OX--->X+X+O2 Net Rxn: 2O3--->3O2
31
Natural X Catalysts
Nitric Oxide (NO) and Hydroxyl Radical (HO)
32
Natural X Catalyst Nitric Oxide (NO)
From soil bacteria From lightning Gets rained out Destroys O3 via mechanism II
33
Natural X Catalyst Hydroxyl Radical (HO)
Produced everywhere Destroys O3 via mechanism I & II Most overall important natural X catalyst
34
Smog timeline
8am NO up 12 NO2 up 5pm HNO3 and O3 up organic compounds from photochemical reactions rise throughout the day VOC's rise till late morning then fall off through the rest of the day
35
1st catalytic converters on cars in the 70s
Run carburetor fuel RICH excess fuel Use up all O2 so no NOx production VOCs released from engine get oxidized in catalytic converter
36
2nd Catalytic converters on cars in the 80s
Run carburetor fuel LEAN excess O2 Use up all fuel so no VOC release NOx produced in engine gets reduced in catalytic converter
37
Conditions favorable for SMOG
Trafic Sunlight and warm temps Stagnant air mass (warm over cold)
38
Sources of VOC's
Incompletely combusted fules Solvents that evaporated Butane spray cans Natural VOCs form trees
39
Sources of NOX
Internal combustion engine Coal, natural gas, electric Lightning Soil bacteria
40
What causes a longer retention time in Ion Chromatography?
Attraction to the stationary phase
41
What causes a shorter retention time in Ion Chromatography?
Affinity to the stationary phase
42
Ion Chromatography For HNO3 (nitric acid) --->
[NO3-]=[HNO3]
43
Ion Chromatography For H2SO4 --->
[SO4 2-] sometimes=[H2SO4] or lower
44
In chromotography what is the order of retention time slowest to fastest for: NO3- Cl- SO4 2-
SO4 2- 7.9 mins NO3- 3.9 mins Cl- 2.1 mins
45
Primary Pollutants
Car exhaust Power plants Natural sourses
46
Secondary Pollutants
Transformation products produced by photo chemical reactions e.g. organic compounds O3, HNO3
47
Biocide experiment: If peaks stayed then they where...
being consumed by a biological process
48
Biocide experiment: If peaks went away then they where...
being consumbed by a physical process
49
Ozone Concentration/AQI numbers: Wilmington
<100
50
Ozone Concentration/AQI numbers: Mexico City
400-500
51
Ozone Concentration/AQI numbers: China
500+
52
Ozone Concentration/AQI numbers: Charlotte NC
150
53
Ozone Concentration/AQI numbers: LA
Old: 600+ New: <200
54
Ozone Concentration/AQI numbers: Clean air
20-30
55
pH rain water
5.6
56
PPM atmospheric CO2
400
57
HNO3 sources
internal combustion engines and soil bacterial and lightning
58
SO4 sources
H2SO4 and sea salts. (if Cl is present then it came from or near by the ocean)
59
Emar
All ocean
60
Emix 1
mostly ocean with a little land
61
Emix 2
more ocean than land
62
Emix 3
more land than ocean
63
Eter
All land
64
Changes in organic acid concentration in Wilmington's rain water: 1987-1989
3:1 Formic Acid:Acetic Acid
65
Changes in organic acid concentration in Wilmington's rain water: 1996-1998
1:1 Formic Acid:Acetic Acid
66
Stokes Law
The rate at which a particle falls is proportional to the square of its diameter Ex Diameter Square of Diamiter Fall rate 10um = 100 = 1.0m/min 20um = 400 = 4.0m/min
67
Fate of Atmospheric Compounds: Removed by rainwater
Anything water soluble Salts (NaCl) Acids (HCl, H2SO4, HNO3) Water soluble organics (ethanol)
68
Fate of Atmospheric Compounds: Removal by Reactions with Hydroxyl Radical (OH)
Ex. O=S=O, CCl3H, CH4
69
Fate of Atmospheric Compounds: Photodecomposition
H2CO->H+HCO
70
Fate of Atmospheric Compounds: If not removed by rainwater, reaction with OH, or photodecomposition
Substance will make it to the stratosphere
71
Fate of Atmospheric Compounds: Polar/water soluble
Rained out
72
Fate of Atmospheric Compounds: Non-polar/non-reacting
Stratosphere
73
Radon: Alpha decay
Short half life Major health hazard Atomic mass decreases by 4 and atomic number decreases by 2
74
Radon: Beta decay
Long Half life Less health hazard Atomic number is increased by 1
75
Indoor Pollutants decay rate
about 4 days
76
Fate of light from sun to earth
Light 100% to atmosphere Atmosphere loses 20% Remaining 80% to Earth Earth absorbs 50% (of 100% total) Remaining 30% reflected
77
Symmetrical stretching (CO2 & O2)
No change in center of positive and negative charge during vibration In this vibrational state CO2 does not absorb IR
78
Anti-symmetrical stretching (CO2)
Change in center of positive and negative charge during this vibration
79

Environmental Chemistry (5 decks)

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