# Shared Flashcard Set

## Details

Physics 472
Final
118
Physics
05/12/2010

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 O2O2 --> 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 O3O3 --> O2+O
Definition
 EndothermicRequires 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 + O2and,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+O2and, 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+Oo2+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- CCl4Trichloroethane- 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 weakestH-FH-ClH-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 + CH3ClO+NO2---> ClNO3
Term
 what happens to the inactive forms of Cl?
Definition
 ClNO3+ H2O---> HOCl+HNO3HCl--->H+ClCl+HOCl---> Cl2+OHCl2---> 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 trichloroethaneit 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
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
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
Term
Definition
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/year30%-cosmic rays50%-gamma emitted from materials in the enviro20%- 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*---> H2O2H2O2---> 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
Definition
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 Aarea = APower = Psolar 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 reactionor D-T reactionD 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
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
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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