Quiz 4 Flashcards
To produce the Dioxin, Cl must be in what position next to the O?
alpha position
Toxicity of Dioxin
Most toxic
Toxicity of Dioxin
Least toxic
What is the requirmen for a phenoxide ion to form a dioxine?
A lot of heat and the Cl atom next to the O atom such as in Agent Orange
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?
6.0 ppm/2.0 ppm/yr=3.0 yr
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?
1 half life 400->200
2 half lives 200->100
3 half lives 100->50
4 half lives 50->25
Answer: 25 ppm
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?
CSS=1.45 X 1.0 mg Hg2+(aq) / day X 6.0 days = 9.0 mg Hg2+(aq)
Toxicity of Metals and Speciation:
Not Toxic
Hg (l)
Pb (s)
Cd (s)
As (s)
Toxicity of Metals and Speciation:
Toxic
Hg (g)
Metals as cations
Hg2+(aq), Pb2+(aq), Cd2+(aq), and As3+(aq)
Toxicity of Metals and Speciation:
Most Toxic
Metals bound to small organics i.e. CH3HgCH3
Spacial distribution of ozone in the Arctic
~450-550 DU
Spacial distribution of ozone in the temperate
~300-375 DU
Spacial distribution of ozone in the tropics
~225-250 DU
Spacial distribution in the ozone hole
~150 DU
1 Dobson Unit DU is equivalent to how many cm?
0.001
1 Dobson Unit DU is equivalent to how many mm?
0.01
UV light range for UVA
320-420 nm
UV light range for UVB
280-320 nm
UV light range for UVC
200-280 nm
How much UV is removed by O2
Most of UVC
How much UV is removed by O3
All of UVC and most of UVB
How much UV makes it to earth
All of UVA and some of UVB
Regions of the Atmosphere: Stratosphere
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
Regions of the Atmosphere: Tropopause
Where temp vs altitude trend changes
-56 Celsius
Altitude 10-15 km
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
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
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
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
Mechanism I
Step I: X+O3—>OX+O2
Step II: OX+O—>X+O2
Net Rxn: O3+O—>2O2
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
Natural X Catalysts
Nitric Oxide (NO) and Hydroxyl Radical (HO)
Natural X Catalyst Nitric Oxide (NO)
From soil bacteria
From lightning
Gets rained out
Destroys O3 via mechanism II
Natural X Catalyst Hydroxyl Radical (HO)
Produced everywhere
Destroys O3 via mechanism I & II
Most overall important natural X catalyst
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
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
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
Conditions favorable for SMOG
Trafic
Sunlight and warm temps
Stagnant air mass (warm over cold)
Sources of VOC’s
Incompletely combusted fules
Solvents that evaporated
Butane spray cans
Natural VOCs form trees
Sources of NOX
Internal combustion engine
Coal, natural gas, electric
Lightning
Soil bacteria
What causes a longer retention time in Ion Chromatography?
Attraction to the stationary phase
What causes a shorter retention time in Ion Chromatography?
Affinity to the stationary phase
Ion Chromatography
For HNO3 (nitric acid) —>
[NO3-]=[HNO3]
Ion Chromatography
For H2SO4 —>
[SO4 2-] sometimes=[H2SO4]
or lower
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
Primary Pollutants
Car exhaust
Power plants
Natural sourses
Secondary Pollutants
Transformation products produced by photo chemical reactions e.g. organic compounds O3, HNO3
Biocide experiment:
If peaks stayed then they where…
being consumed by a biological process
Biocide experiment:
If peaks went away then they where…
being consumbed by a physical process
Ozone Concentration/AQI numbers:
Wilmington
<100
Ozone Concentration/AQI numbers:
Mexico City
400-500
Ozone Concentration/AQI numbers:
China
500+
Ozone Concentration/AQI numbers:
Charlotte NC
150
Ozone Concentration/AQI numbers:
LA
Old: 600+
New: <200
Ozone Concentration/AQI numbers:
Clean air
20-30
pH rain water
5.6
PPM atmospheric CO2
400
HNO3 sources
internal combustion engines and soil bacterial and lightning
SO4 sources
H2SO4 and sea salts. (if Cl is present then it came from or near by the ocean)
Emar
All ocean
Emix 1
mostly ocean with a little land
Emix 2
more ocean than land
Emix 3
more land than ocean
Eter
All land
Changes in organic acid concentration in Wilmington’s rain water:
1987-1989
3:1 Formic Acid:Acetic Acid
Changes in organic acid concentration in Wilmington’s rain water:
1996-1998
1:1 Formic Acid:Acetic Acid
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
Fate of Atmospheric Compounds:
Removed by rainwater
Anything water soluble
Salts (NaCl)
Acids (HCl, H2SO4, HNO3)
Water soluble organics (ethanol)
Fate of Atmospheric Compounds:
Removal by Reactions with Hydroxyl Radical (OH)
Ex. O=S=O, CCl3H, CH4
Fate of Atmospheric Compounds:
Photodecomposition
H2CO->H+HCO
Fate of Atmospheric Compounds:
If not removed by rainwater, reaction with OH, or photodecomposition
Substance will make it to the stratosphere
Fate of Atmospheric Compounds:
Polar/water soluble
Rained out
Fate of Atmospheric Compounds:
Non-polar/non-reacting
Stratosphere
Radon:
Alpha decay
Short half life
Major health hazard
Atomic mass decreases by 4 and atomic number decreases by 2
Radon:
Beta decay
Long Half life
Less health hazard
Atomic number is increased by 1
Indoor Pollutants decay rate
about 4 days
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
Symmetrical stretching (CO2 & O2)
No change in center of positive and negative charge during vibration
In this vibrational state CO2 does not absorb IR
Anti-symmetrical stretching (CO2)
Change in center of positive and negative charge during this vibration
