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Physics 472
Final
118
Physics
Undergraduate 2
05/12/2010

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Term
The sun emits what UV range most?
Definition
A>B>C
Term
What ranges of UV have very harmful biological effects?
Definition
c and B
Term
The ozone layer screens out what percent of UV B
Definition
80%
Term
Where is the ozone of the ozone layer created?
Definition
In the atmosphere, not on earth's surface
Term
Photodissociation of O2
O2 --> O+O
Definition
Reaction is strongly endothermic requiring an input of 495 kJ/mol or 4.77 eV, which is in the UV-C. There are not many photons in UV-C.
Term
No UVC reaches the earth because of what molecule?
Definition
O2
Term
Photodissociation of O3
O3 --> O2+O
Definition
Endothermic
Requires 105 kJ/mol, which is less than O2 reaction.
Term
At what UV range does o3 absorb most strongly?
Definition
UV B
Term
What biological effects does UVB have?
Definition
sunburn and genetic disruption
Term
Almost all of the UVA reaches the surface
Definition
SHUT UP... I know this isn't a question.... BUT KNOW IT!
Term
Rate Constant k
Definition
There are factors that a reaction must overcome to go. For example if it is endothermic or has a reaction barrier. These factors determine the actual probability of the reaction once the encounter has taken place and this is what k is summarized as.
Term
What is k proportional to if there is an energy barrier Esub b?
Definition
exponent(-Esub b/kbT) when kb = universal Boltzmann constant.
Term
What is the Dobson unit and why do we use it?
Definition
The dobson unit is the thickness of the layer that the gas would form if it were all brought to a standard pressure and temperature at the surface of earth. The reason for the dobson unit is: ozone concentration varies by greatly by altitude and the total ozone in a column of unit area is more important than the concentration at any particular height.
Term
There are three (variations) for break down ozone what is result of the first X + O3 -->
Definition
--> XO + O2
and,XO + O --> X+02 NET= O3+O > O2
Term
For this reaction, X + photon --> Y, at what rate does it proceed at?
Definition
R = k[X][v]
where v is the flux of photons of the proper wavelength through the region where the reaction happens.
Term
There are three (variations) for break down ozone what is result of the first X + O3 -->
Definition
--> XO + O2 and, X'+O3-->X'O+O2
and, XO+X'O-->X+X'+O2 NET 2O3-->3O2
Term
What equations cause ozone levels to peak in the mid to low stratospheric levels?
Definition
the chain reaction of:
O2+UVC-->o+O
o2+0---> o3
Term
What is the single largest source of Cl in our atmosphere?
Definition
CFC (chlorofluorocarbons)
Term
CFC-11
Definition
CFCl3
Term
What is the most prevalent element in Ozone destruction and one reason why?
Definition
Chlorine Cl, REACTIVE, needs one electron to fill outer shell
Term
CFC-12
Definition
CF2Cl2
Term
What properties of CFCs are ideal?
Definition
inert, nonflammable gas,boiling point near room temp. so it can be transported and stored as a liquid and used as a gas
Term
Why are CFCs inert?
Definition
C-Cl--->81Kcal/mole
Term
Chapman Cycle
Definition
[image]
Term
Chlorine Destruction equation GO:
Cl+O3 --> ??
Definition
Cl+O3->ClO+O2 (twice)
ClO+ClO->Cl2O2, then Cl2O2 +UVC-> ClO2+Cl,
then, ClO2->O2+Cl, NET: 2O3 -> 3O2
Term
The break down of CFC-12 by UVc once it gets to stratosphere
Definition
Cf2Cl2+UVC--->CF2Cl+Cl
Term
The break down of CFC-11 by UVC once it gets to the stratosphere
Definition
CFCl3+UVC---> CFCl2+Cl
Term
Two other main sources of Cl in the atmosphere
Definition
Carbon tetrachloride- CCl4
Trichloroethane- C2H3Cl3
Term
What is dangerous about the release of the Cl molecule into the atmosphere?
Definition
catalytic ozone destruction
Term
What is another radical that is dangerous in the atmosphere that is released from some cleaners?
Definition
Br
Term
What does LD50 mean?
Definition
Lethal dose that kills 50% of the population
Term
Rank the strength of these bonds- Strongest to weakest
H-F
H-Cl
H-Br
Definition
H-f>H-cl>H-Br
Term
What are the two main classes of Bromine containing compounds?
Definition
Halons( compounds that contain bromine but no hydrogen- CF3Br)
methyl bromide
Term
On a lethal dose curve where are the threshold points?
Definition
LD5 and LD50
Term
Why are HCFC's a better for the environment than CFC's?
Definition
The C-H bond is more susceptible to chemical attack than the C-Cl bond, so these compounds are broken down already in the troposphere for the most part. Also it does not create HCl. They still do destroy ozone though. HFC's are the ideal replacement.
Term
the ozone holes appear only near the...
Definition
poles
Term
What time of the year do we see the hole?
Definition
September (australia spring time) and is pretty much gone by december
Term
Reactions that take place to get rid of Cl and ClO (elements/compounds that destroy ozone)
Definition
Cl+ CH4--> HCl + CH3
ClO+NO2---> ClNO3
Term
what happens to the inactive forms of Cl?
Definition
ClNO3+ H2O---> HOCl+HNO3
HCl--->H+Cl
Cl+HOCl---> Cl2+OH
Cl2---> is gas and escapes into the atmosphere and is decomposed by UV light and atomic chlorine catalyzes ozone destruction
Term
What is significant about the north and south pole in the activation of Cl?
Definition
Normally there is no weather in the stratosphere but in the north and south pole, polar stratospheric clouds (PSCs) will form in -80C. These ice clouds have a thin layer of water on them that can activate the Cl
Term
What is significant about the north and south pole in the activation of Cl?
Definition
Normally there is no weather in the stratosphere but in the north and south pole, polar stratospheric clouds (PSCs) will form in -80C. These ice clouds have a thin layer of water on them that can activate the Cl
Term
Bioconcentration
Definition
AKA biomagnification. The fat-soluble molecules are eaten by organisms low on the food chain. They build up a certain low concentration. An organism high up in the food chain eats the lower one. It is not able to excrete this substance and therefore, as time goes on the toxin builds up.
Term
What explains why the ozone hole starts in the spring and is not apparent in the winter
Definition
In the polar winter there is no sunlight (UV) to activate the Cl
Term
In which pole is the hole larger?
Definition
South
Term
DDT
Definition
para dichloro diphenyl trichloroethane
it is persistent because:
low volatility (tendency of a substance to vaporize)
No bonds which can be broken by visible light.
chemical and biological stability (C-Cl bonds very strong)
Very low solubility in water (has no O atoms - not polar thus not soluble)(if it is not water soluble it can not be excreted)
highly toxic to insects.
It does biocencentrate.
Term
Why is oil considered a finite resource?
Definition
100,000 yr time scale for the formation of oil and the 100-200 year time scale oh which we are using it. Also the price run up in the last few years
Term
What do living organisms change DDT to?
Definition
DDE, which = DDT minus and H a Cl.
Term
When we look at how much oil is on left on earth we are talking about light sweet crude oil... what does this mean?
Definition
It can be pumped from the ground and does not contain much sulfur
Term
How did Hubbert predict the peak of oil production would be in 1970?
Definition
made assumption that the amount produced in a given year divided by the cumulative amount produced up until that year would be proportional to the amount left in the ground
Term
Production rate/amount already produced= K x (amount left)
Definition
K is a proportionality constant and total just refers to the total amount in the ground.(about oil in ground)
Term
What is the problem with oil from tar sands?
Definition
The oil is bonded to sand and must be removed by mixing the sand with very hot water and NaOH- need large amounts of water and energy
Term
Look into the linear and bell graph relationship of oil production- lecture 41- do not know how to put into notecards... sorry my loves!
Definition
Term
Natural radioactive elements
Definition

The series with 92U238 and continues all the way to Pb206. In all reaction chains it begins with a long-lived radioactive species and ends with a stable ones.

See lecture 37 for graph.

Term
Fission reactions
Definition
The neutron is absorbed by the 92U235 whcih converts to the highly unstable 92U236, which spontaneously splits into two smaller pieces. An example:
92U235 + 1n0 → 92U236 → 35Br89 + 57La144 + 3 1n0,
Term
What is the form most natural radioactivity we are exposed to is?
Definition
Gamma rays
Term
What is more raidoactive? Us or our surroundings?
Definition
Humans due to the radioactive K in our bodies.
Term
What is the fate of the alpha particle?
Definition
they are charged so they bang into electrons in the atoms on their path (ionize).The more dense the material the quicker the alpha particle comes to a stop because it transfers energy to the electrons until it has none
Term
fate of the beta particle
Definition
lighter and travel in a less straight path. smaller charge so it can go further
Term
Fate of a gama particle
Definition
not charged so much more penetrating. can ionize atoms
Term
what is background radiation
Definition
gamma ray and internal emissions. we are not close enough to external pure alpha and beta sources to get radioactivity from them
Term
what does a curie measure
Definition
strength of a radioactive source
Term
what does a rad measure
Definition
the dosage of ionizing radiation
Term
the rem
Definition
used for biological applications and is the dosage of ionizing radiation measured in different biological densities
Term
What is characteristic of the nuclear fission fragments that break up after the primary reactions?
Definition
They are two large fragments of unequal weight caused by reactions of heavy nuclei.
Term
What is the natural dosage of radiation per year?
Definition
100 millirads/year
30%-cosmic rays
50%-gamma emitted from materials in the enviro
20%- internal emissions
Term
Nuclear reactions
Definition
Neutrons appear on both sides but after the reaction there are more neutrons than before, which can initiate more reactions producing a chain reactions. Each step releases energy.
Term
What is the fuel for nuclear reactors?
Definition
92U235. The problem is that natural uranium is 99.3% 92U238 and .7% 92U235. This needs to be enriched by separation to 3-5%.
Term
when water is ionized
Definition
H20-->H2O^+ + e^-
H2O^+--> H^+ + OH*
OH* + OH*---> H2O2
H2O2---> undesirable
Term
What does the moderator do in nuclear reactions?
Definition
it slows down the neutrons so a chain reaction can be achieved. Graphite (carbon) or water is often used
Term
Nuclear reactors common parts
Definition
a core containing the nuclear fuel, moderator, control rods and coolant.
Term
what cells are damaged by radiation
Definition
rapidly dividing ones
Term
what is the LD50 in rads of radiation
Definition
500 rads
Term
explain the threshold model of radiation
Definition
At small amounts it does not cause cancer because we have a natural defense against it. (we have mechanisms for repairing damaged DNA)
Term
explain the linear model of radiation
Definition
the amount of genetic material damaged is proportional to the dose and the chance of cancer is in turn proportional to the genetic damage
Term
Types of Nuclear reactors
Definition
Boiling water reactor. Water acts as bot a coolant and a moderator in the core. This water runs through the turbine and back to the core.
Pressurized water reactors (most common) - which differ from boiling water reactors only in that the primary coolant, water, does not boil and does not get to the turbines. As a safety precaution they both will stop moderation and radiation if the coolant is lost.
Fission reactor - the fission reactions can take many different paths.
Term
what is an alpha ray?
Definition
Fast moving He Nucleus
Term
what is a beta ray?
Definition
fast moving electron
Term
what is a gamma ray?
Definition
high-energy photon
Term
Three Mile Island
Definition
started by a valve sticking in the condenser, which prevented the flow of coolant water to the core.
Term
an isotope
Definition
same number of protons but different number of neutrons
Term
Chernobyl
Definition
Emergency power was shut off and the temperature of the water was turned down. Usually it is hard to restart due to the buildup of Xe135 but the operators restarted it anyway.
Term
What is the most stable nucleus
Definition
26Fe56- highest binding energy per nucleon
Term
what do elements higher than Fe56 tend to do?
Definition
Split up because they are unstable and lighter nuclei tend to fuse together
Term
Why are there no elements heavier than uranium on earth?
Definition
Nuclei decay at varying rates and decay faster as the atomic number increases. when the atomic number is greater than uranium (92), the rates are fast compared to the age of the earth so there are no elements heavier than this
Term
When is a element thought of as radioactive
Definition
if the half life is shorter than 10^10 years
Term
an example of alpha decay
Definition
90Th232---> 88Ra228 + 2He4
Term
Calculation efficiency factor (EFF)
Definition
P = EFF x C x A
area = A
Power = P
solar constant = C
Term
example of Beta decay
Definition
88Ra228--> 89Ac228 + e-
Term
What do solar cells use to conduct electricity?
Definition
semiconductors, which is a material that is an insulator in its pristine state. To make electricity you need to coax the free electrons generated into an external circut before they recombine.
Term
Photovoltaic cells
Definition
Use the concept of p-n junction. Difference is that instead of semi-conductors, silicon is being used. So basically it is p-n because electrons create holes once they are absorbed and these holes are swept to the electrodes.
Term
Drawbacks of solar
Definition
Expensive and only a fraction of the solar constant is absorbed. Costs about $.30/kW-hr. This is due to the high cost of Si.
Term
when a nucleus decays,what does almost all the energy appear as?
Definition
kinetic energy of the lighter fragment
Term
there is usually a gamma ray with alpha and beta decay
Definition
Term
Basic Fusion Energy reaction
or D-T reaction
D is heavy hydrogen and T is tritium.
Definition
2H+ 3H --> 4He (3.5 MeV) + n (14.1 MeV)
This reaction is very potent because of the extreme stability of the He nucleus.
Term
Positives and Negatives of fusion
Definition
not radioactive so not dangerous. Also, D is plentiful, but you need to accelerated toward one another. Or at a very high temperature. T must be manufactured.
Term
What are the human bodies defensive mechanisms to toxins?
Definition
Excretion, through kidneys, lungs, liver (water soluble only) AND Metabolism (fat soluble toxins are processed
Term
What was a remedy for treating toxins developed by Britains?
Definition
British Anti-Lewisite (bonds to metallic toxins) and makes them water soluble so they body can process them
Term
What equation determines bioaccumulation of toxins? (think Homework)
Definition
C= Csub(s)*(1-e^-k*t) where C= final conc, Csub(s)=intake/elimination efficiency, k is elim eff., t is time
Term
What are organochlorines and what do they consist of?
Definition
Used in pesticides/herbicides they consist of: benzene rings and chlorine therefore they persist in the environment
Term
Name some common organophosphates (Same as organochlorines but with PO group) also are used as pesticides.
Definition
Dichlorvos(LD50= 25mg/kg) Parathion(LD50 =3mg/kg) Malathion(880mg/kg) These mess with the nervous system of insects
Term
Name two choloracetamides. (mixture of the two was made popular in Vietnam)
Definition
Agent Orange: consisted of common weed killers dichlorophenoxyacetic acid and trichloro... same as prior (remember structure from homework
Term
Why is tetrodotoxin (natural,puffer fish toxin) so harmful?
Definition
LD50=mg It binds to Sodium(Na) channels in nerve cells causes paralysis
Term
Important! Discuss ciguatoxin (prof Joynt's toxin)
Definition
Produced by algae and bioaccumulates in fish, people eat fish and get sick. Affects sensory nerve conduction, can take years to get rid of.
Term
What are PCBs and why are they harmful to environment?
Definition
Phenyl rings with Cl subsituted for H. Used in insulators and dumped into envir. Persist b/c of Cl, sit in riverbeds and are fat soluble, can bioaccumulate
Term
What are the 3 important toxic actions of metals?
Definition
1. Inhibit enzymes 2.Subsitute Chelated ion (prevent hemoglobin for transporting oxygen) 3.Disrupts nerve conduction
Term
Why is CH3Hg (methyl mercury) such a harmful molecule?
Definition
Bioaccumulates, affects child development, Low LD50, sensory impairment(paresthesia), ataxia(muscle control), dysarthria(slurred speech)
Term
Why is lead such a bad naturally occurring toxin?
Definition
In drinking water, gases, can get into body and cause gastrointestinal/nerve problems, anemia, BIGGEST effect on development of children (dumber kids)
Term
What are common units of energy we used in class?
Definition
eV electron volt (chemistry), MeV(10^6eV)nuclear scale, Joule(human level, 1food cal=1000 scientific cal=4.184*10^3Joules, Btu(British thermal unit 1=1055J, 1Kw/hr=3.6*10^6J, National QuadBtu=10^15Btu
Term
How many gallons in a barrel of oil? Btu's in 1 ton of coal?
Definition
42, 2.66*10^7Btu ~roughly 4 barrels of oil
Term
What is the largest source of energy production in US? What is greatest sourced consumed (i.e. what do we import)?
Definition
Coal, Petroleum
Term
What is total US energy use, per person?
Definition
100 QuadBtu's=1.055*10^20J/yr
1.055*10^20J/3*10^7s= 3*10^12W in power, so each person uses about 10000W/yr
Term
How does a power plant work?
Definition
Fuel is burned, heats water, creates steam that goes through turbines, and turns electrical coils in a magnetic field in a generator that creates electricity Specifically 1.Compression of water 2.Boiling 3.Expansion of Steam 4.Condensing (steam cools back to cold water)
Term
How does a power plant work?
Definition
Fuel is burned, heats water, creates steam that goes through turbines, and turns electrical coils in a magnetic field in a generator that creates electricity
Term
Where does heat come from in a combustion reaction?
Definition
CH4+2O2->CO2+H2O+HEAT
1kg of methane produces 55MJ of heat energy
Term
What is the equation for EFF?
Definition
Efficiency= Work given out-work put in)/Heat so, EFF= 1-T(envr)/T(combustion) T(envr) = 285K Modern powerplants=0.4 EFF
Term
How do you measure Power out of a plant?
Definition
P(out)=EFFactual*H*R (R=fuel consumed) (H=heat of combustion per kg H)
example: 200MW/(.4*55MJ)=8.3kg/s*3600=
29,880kg of CH4 per hour
Term
How do you solve global warming?
Definition
Stabilization wedges(Small Changes) don't be "Business as usual." Wedge categories include: Efficiency/Conservation, Fuel Shifts, and Carbon Sinks (forest management) ASK MATT if u want more detail :D
Term
there is usually a gamma ray with alpha and beta decay
Definition
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