Term
The sun emits what UV range most? |
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Definition
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What ranges of UV have very harmful biological effects? |
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Definition
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The ozone layer screens out what percent of UV B |
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Definition
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Term
Where is the ozone of the ozone layer created? |
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Definition
In the atmosphere, not on earth's surface |
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Term
Photodissociation of O2 O2 --> O+O |
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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. |
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Term
No UVC reaches the earth because of what molecule? |
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Definition
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Term
Photodissociation of O3 O3 --> O2+O |
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Definition
Endothermic Requires 105 kJ/mol, which is less than O2 reaction. |
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Term
At what UV range does o3 absorb most strongly? |
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Definition
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What biological effects does UVB have? |
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Definition
sunburn and genetic disruption |
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Almost all of the UVA reaches the surface |
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Definition
SHUT UP... I know this isn't a question.... BUT KNOW IT! |
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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. |
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Term
What is k proportional to if there is an energy barrier Esub b? |
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Definition
exponent(-Esub b/kbT) when kb = universal Boltzmann constant. |
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Term
What is the Dobson unit and why do we use it? |
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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. |
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Term
There are three (variations) for break down ozone what is result of the first X + O3 --> |
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Definition
--> XO + O2 and,XO + O --> X+02 NET= O3+O > O2 |
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Term
For this reaction, X + photon --> Y, at what rate does it proceed at? |
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Definition
R = k[X][v] where v is the flux of photons of the proper wavelength through the region where the reaction happens. |
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Term
There are three (variations) for break down ozone what is result of the first X + O3 --> |
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Definition
--> XO + O2 and, X'+O3-->X'O+O2 and, XO+X'O-->X+X'+O2 NET 2O3-->3O2 |
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Term
What equations cause ozone levels to peak in the mid to low stratospheric levels? |
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Definition
the chain reaction of: O2+UVC-->o+O o2+0---> o3 |
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Term
What is the single largest source of Cl in our atmosphere? |
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Definition
CFC (chlorofluorocarbons) |
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Term
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Definition
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What is the most prevalent element in Ozone destruction and one reason why? |
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Definition
Chlorine Cl, REACTIVE, needs one electron to fill outer shell |
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Term
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Definition
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What properties of CFCs are ideal? |
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Definition
inert, nonflammable gas,boiling point near room temp. so it can be transported and stored as a liquid and used as a gas |
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Definition
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Term
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Definition
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Chlorine Destruction equation GO: Cl+O3 --> ?? |
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Definition
Cl+O3->ClO+O2 (twice) ClO+ClO->Cl2O2, then Cl2O2 +UVC-> ClO2+Cl, then, ClO2->O2+Cl, NET: 2O3 -> 3O2 |
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Term
The break down of CFC-12 by UVc once it gets to stratosphere |
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Definition
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Term
The break down of CFC-11 by UVC once it gets to the stratosphere |
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Definition
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Term
Two other main sources of Cl in the atmosphere |
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Definition
Carbon tetrachloride- CCl4 Trichloroethane- C2H3Cl3 |
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Term
What is dangerous about the release of the Cl molecule into the atmosphere? |
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Definition
catalytic ozone destruction |
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Term
What is another radical that is dangerous in the atmosphere that is released from some cleaners? |
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Definition
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Term
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Definition
Lethal dose that kills 50% of the population |
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Term
Rank the strength of these bonds- Strongest to weakest H-F H-Cl H-Br |
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Definition
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Term
What are the two main classes of Bromine containing compounds? |
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Definition
Halons( compounds that contain bromine but no hydrogen- CF3Br) methyl bromide |
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Term
On a lethal dose curve where are the threshold points? |
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Definition
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Term
Why are HCFC's a better for the environment than CFC's? |
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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. |
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Term
the ozone holes appear only near the... |
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Definition
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Term
What time of the year do we see the hole? |
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Definition
September (australia spring time) and is pretty much gone by december |
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Term
Reactions that take place to get rid of Cl and ClO (elements/compounds that destroy ozone) |
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Definition
Cl+ CH4--> HCl + CH3 ClO+NO2---> ClNO3 |
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Term
what happens to the inactive forms of Cl? |
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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 |
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Term
What is significant about the north and south pole in the activation of Cl? |
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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 |
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Term
What is significant about the north and south pole in the activation of Cl? |
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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 |
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Term
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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. |
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Term
What explains why the ozone hole starts in the spring and is not apparent in the winter |
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Definition
In the polar winter there is no sunlight (UV) to activate the Cl |
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Term
In which pole is the hole larger? |
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Definition
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Term
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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. |
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Term
Why is oil considered a finite resource? |
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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 |
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Term
What do living organisms change DDT to? |
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Definition
DDE, which = DDT minus and H a Cl. |
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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? |
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Definition
It can be pumped from the ground and does not contain much sulfur |
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Term
How did Hubbert predict the peak of oil production would be in 1970? |
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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 |
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Term
Production rate/amount already produced= K x (amount left) |
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Definition
K is a proportionality constant and total just refers to the total amount in the ground.(about oil in ground) |
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Term
What is the problem with oil from tar sands? |
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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 |
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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! |
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Definition
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Term
Natural radioactive elements |
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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. |
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Term
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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, |
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Term
What is the form most natural radioactivity we are exposed to is? |
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Definition
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Term
What is more raidoactive? Us or our surroundings? |
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Definition
Humans due to the radioactive K in our bodies. |
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Term
What is the fate of the alpha particle? |
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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 |
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Term
fate of the beta particle |
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Definition
lighter and travel in a less straight path. smaller charge so it can go further |
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Term
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Definition
not charged so much more penetrating. can ionize atoms |
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Term
what is background radiation |
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Definition
gamma ray and internal emissions. we are not close enough to external pure alpha and beta sources to get radioactivity from them |
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Term
what does a curie measure |
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Definition
strength of a radioactive source |
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Term
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Definition
the dosage of ionizing radiation |
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Term
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Definition
used for biological applications and is the dosage of ionizing radiation measured in different biological densities |
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Term
What is characteristic of the nuclear fission fragments that break up after the primary reactions? |
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Definition
They are two large fragments of unequal weight caused by reactions of heavy nuclei. |
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Term
What is the natural dosage of radiation per year? |
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Definition
100 millirads/year 30%-cosmic rays 50%-gamma emitted from materials in the enviro 20%- internal emissions |
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Term
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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. |
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Term
What is the fuel for nuclear reactors? |
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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%. |
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Term
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Definition
H20-->H2O^+ + e^- H2O^+--> H^+ + OH* OH* + OH*---> H2O2 H2O2---> undesirable |
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Term
What does the moderator do in nuclear reactions? |
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Definition
it slows down the neutrons so a chain reaction can be achieved. Graphite (carbon) or water is often used |
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Term
Nuclear reactors common parts |
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Definition
a core containing the nuclear fuel, moderator, control rods and coolant. |
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Term
what cells are damaged by radiation |
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Definition
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Term
what is the LD50 in rads of radiation |
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Definition
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Term
explain the threshold model of radiation |
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Definition
At small amounts it does not cause cancer because we have a natural defense against it. (we have mechanisms for repairing damaged DNA) |
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Term
explain the linear model of radiation |
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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 |
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Term
Types of Nuclear reactors |
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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. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
started by a valve sticking in the condenser, which prevented the flow of coolant water to the core. |
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Term
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Definition
same number of protons but different number of neutrons |
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Term
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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. |
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Term
What is the most stable nucleus |
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Definition
26Fe56- highest binding energy per nucleon |
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Term
what do elements higher than Fe56 tend to do? |
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Definition
Split up because they are unstable and lighter nuclei tend to fuse together |
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Term
Why are there no elements heavier than uranium on earth? |
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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 |
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Term
When is a element thought of as radioactive |
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Definition
if the half life is shorter than 10^10 years |
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Term
an example of alpha decay |
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Definition
90Th232---> 88Ra228 + 2He4 |
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Term
Calculation efficiency factor (EFF) |
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Definition
P = EFF x C x A area = A Power = P solar constant = C |
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Term
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Definition
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Term
What do solar cells use to conduct electricity? |
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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. |
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Term
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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. |
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Term
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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. |
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Term
when a nucleus decays,what does almost all the energy appear as? |
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Definition
kinetic energy of the lighter fragment |
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Term
there is usually a gamma ray with alpha and beta decay |
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Definition
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Term
Basic Fusion Energy reaction or D-T reaction D is heavy hydrogen and T is tritium. |
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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. |
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Term
Positives and Negatives of fusion |
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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. |
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Term
What are the human bodies defensive mechanisms to toxins? |
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Definition
Excretion, through kidneys, lungs, liver (water soluble only) AND Metabolism (fat soluble toxins are processed |
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Term
What was a remedy for treating toxins developed by Britains? |
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Definition
British Anti-Lewisite (bonds to metallic toxins) and makes them water soluble so they body can process them |
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Term
What equation determines bioaccumulation of toxins? (think Homework) |
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Definition
C= Csub(s)*(1-e^-k*t) where C= final conc, Csub(s)=intake/elimination efficiency, k is elim eff., t is time |
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Term
What are organochlorines and what do they consist of? |
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Definition
Used in pesticides/herbicides they consist of: benzene rings and chlorine therefore they persist in the environment |
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Term
Name some common organophosphates (Same as organochlorines but with PO group) also are used as pesticides. |
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Definition
Dichlorvos(LD50= 25mg/kg) Parathion(LD50 =3mg/kg) Malathion(880mg/kg) These mess with the nervous system of insects |
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Term
Name two choloracetamides. (mixture of the two was made popular in Vietnam) |
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Definition
Agent Orange: consisted of common weed killers dichlorophenoxyacetic acid and trichloro... same as prior (remember structure from homework |
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Term
Why is tetrodotoxin (natural,puffer fish toxin) so harmful? |
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Definition
LD50=mg It binds to Sodium(Na) channels in nerve cells causes paralysis |
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Term
Important! Discuss ciguatoxin (prof Joynt's toxin) |
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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. |
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Term
What are PCBs and why are they harmful to environment? |
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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 |
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Term
What are the 3 important toxic actions of metals? |
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Definition
1. Inhibit enzymes 2.Subsitute Chelated ion (prevent hemoglobin for transporting oxygen) 3.Disrupts nerve conduction |
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Term
Why is CH3Hg (methyl mercury) such a harmful molecule? |
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Definition
Bioaccumulates, affects child development, Low LD50, sensory impairment(paresthesia), ataxia(muscle control), dysarthria(slurred speech) |
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Term
Why is lead such a bad naturally occurring toxin? |
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Definition
In drinking water, gases, can get into body and cause gastrointestinal/nerve problems, anemia, BIGGEST effect on development of children (dumber kids) |
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Term
What are common units of energy we used in class? |
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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 |
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Term
How many gallons in a barrel of oil? Btu's in 1 ton of coal? |
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Definition
42, 2.66*10^7Btu ~roughly 4 barrels of oil |
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Term
What is the largest source of energy production in US? What is greatest sourced consumed (i.e. what do we import)? |
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Definition
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Term
What is total US energy use, per person? |
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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 |
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Term
How does a power plant work? |
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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) |
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Term
How does a power plant work? |
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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 |
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Term
Where does heat come from in a combustion reaction? |
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Definition
CH4+2O2->CO2+H2O+HEAT 1kg of methane produces 55MJ of heat energy |
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Term
What is the equation for EFF? |
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Definition
Efficiency= Work given out-work put in)/Heat so, EFF= 1-T(envr)/T(combustion) T(envr) = 285K Modern powerplants=0.4 EFF |
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Term
How do you measure Power out of a plant? |
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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 |
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Term
How do you solve global warming? |
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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 |
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Term
there is usually a gamma ray with alpha and beta decay |
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Definition
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