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Environmental Chemistry > Quiz 4 > Flashcards

Quiz 4 Flashcards

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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
Q

Regions of the Atmosphere: Troposphere

A

Temp decreases with increasing altitude
Well mixed except H2O
IR from surface of earth releases heat
25 to -56 Celsius
Altitude 0-9 km

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26
Q

Regions of the Stratosphere: Upper

A

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

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27
Q

Regions of the Stratosphere: Mid

A

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

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28
Q

Regions of the stratosphere: Lower

A

Air more dense
No UVC needed to produce O via O2->O+O
No O
No O2+O->O3
No O3 formation

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29
Q

Mechanism I

A

Step I: X+O3—>OX+O2
Step II: OX+O—>X+O2
Net Rxn: O3+O—>2O2

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30
Q

Mechanism II

A

Step I: O3+X—>OX+O2
Step II: O3+X—>OX+O2
Step III: OX+OX—>X+X+O2
Net Rxn: 2O3—>3O2

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31
Q

Natural X Catalysts

A

Nitric Oxide (NO) and Hydroxyl Radical (HO)

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32
Q

Natural X Catalyst Nitric Oxide (NO)

A

From soil bacteria
From lightning
Gets rained out
Destroys O3 via mechanism II

33
Q

Natural X Catalyst Hydroxyl Radical (HO)

A

Produced everywhere
Destroys O3 via mechanism I & II
Most overall important natural X catalyst

34
Q

Smog timeline

A

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
Q

1st catalytic converters on cars in the 70s

A

Run carburetor fuel RICH excess fuel
Use up all O2 so no NOx production
VOCs released from engine get oxidized in catalytic converter

36
Q

2nd Catalytic converters on cars in the 80s

A

Run carburetor fuel LEAN excess O2
Use up all fuel so no VOC release
NOx produced in engine gets reduced in catalytic converter

37
Q

Conditions favorable for SMOG

A

Trafic
Sunlight and warm temps
Stagnant air mass (warm over cold)

38
Q

Sources of VOC’s

A

Incompletely combusted fules
Solvents that evaporated
Butane spray cans
Natural VOCs form trees

39
Q

Sources of NOX

A

Internal combustion engine
Coal, natural gas, electric
Lightning
Soil bacteria

40
Q

What causes a longer retention time in Ion Chromatography?

A

Attraction to the stationary phase

41
Q

What causes a shorter retention time in Ion Chromatography?

A

Affinity to the stationary phase

42
Q

Ion Chromatography
For HNO3 (nitric acid) —>

A

[NO3-]=[HNO3]

43
Q

Ion Chromatography
For H2SO4 —>

A

[SO4 2-] sometimes=[H2SO4]
or lower

44
Q

In chromotography what is the order of retention time slowest to fastest for:

NO3-
Cl-
SO4 2-

A

SO4 2- 7.9 mins
NO3- 3.9 mins
Cl- 2.1 mins

45
Q

Primary Pollutants

A

Car exhaust
Power plants
Natural sourses

46
Q

Secondary Pollutants

A

Transformation products produced by photo chemical reactions e.g. organic compounds O3, HNO3

47
Q

Biocide experiment:

If peaks stayed then they where…

A

being consumed by a biological process

48
Q

Biocide experiment:

If peaks went away then they where…

A

being consumbed by a physical process

49
Q

Ozone Concentration/AQI numbers:

Wilmington

A

<100

50
Q

Ozone Concentration/AQI numbers:

Mexico City

A

400-500

51
Q

Ozone Concentration/AQI numbers:

China

A

500+

52
Q

Ozone Concentration/AQI numbers:

Charlotte NC

A

150

53
Q

Ozone Concentration/AQI numbers:

LA

A

Old: 600+

New: <200

54
Q

Ozone Concentration/AQI numbers:

Clean air

A

20-30

55
Q

pH rain water

A

5.6

56
Q

PPM atmospheric CO2

A

400

57
Q

HNO3 sources

A

internal combustion engines and soil bacterial and lightning

58
Q

SO4 sources

A

H2SO4 and sea salts. (if Cl is present then it came from or near by the ocean)

59
Q

Emar

A

All ocean

60
Q

Emix 1

A

mostly ocean with a little land

61
Q

Emix 2

A

more ocean than land

62
Q

Emix 3

A

more land than ocean

63
Q

Eter

A

All land

64
Q

Changes in organic acid concentration in Wilmington’s rain water:

1987-1989

A

3:1 Formic Acid:Acetic Acid

65
Q

Changes in organic acid concentration in Wilmington’s rain water:

1996-1998

A

1:1 Formic Acid:Acetic Acid

66
Q

Stokes Law

A

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
Q

Fate of Atmospheric Compounds:

Removed by rainwater

A

Anything water soluble

Salts (NaCl)
Acids (HCl, H2SO4, HNO3)
Water soluble organics (ethanol)

68
Q

Fate of Atmospheric Compounds:

Removal by Reactions with Hydroxyl Radical (OH)

A

Ex. O=S=O, CCl3H, CH4

69
Q

Fate of Atmospheric Compounds:

Photodecomposition

A

H2CO->H+HCO

70
Q

Fate of Atmospheric Compounds:

If not removed by rainwater, reaction with OH, or photodecomposition

A

Substance will make it to the stratosphere

71
Q

Fate of Atmospheric Compounds:

Polar/water soluble

A

Rained out

72
Q

Fate of Atmospheric Compounds:

Non-polar/non-reacting

A

Stratosphere

73
Q

Radon:

Alpha decay

A

Short half life

Major health hazard

Atomic mass decreases by 4 and atomic number decreases by 2

74
Q

Radon:

Beta decay

A

Long Half life

Less health hazard

Atomic number is increased by 1

75
Q

Indoor Pollutants decay rate

A

about 4 days

76
Q

Fate of light from sun to earth

A

Light 100% to atmosphere
Atmosphere loses 20%
Remaining 80% to Earth
Earth absorbs 50% (of 100% total)
Remaining 30% reflected

77
Q

Symmetrical stretching (CO2 & O2)

A

No change in center of positive and negative charge during vibration

In this vibrational state CO2 does not absorb IR

78
Q

Anti-symmetrical stretching (CO2)

A

Change in center of positive and negative charge during this vibration

79
Q
A

Environmental Chemistry (5 decks)

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