English Montreal School Board Environmental Science & Technology Secondary Cycle II Year II Page 1

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1 C. Accurate interpretation of scientific and messages C2.: Relevant explanations or solutions 2009 EMSB June STE Exam Question : Nuclear Energy PART A: Briefly explain the concept of radioactivity. How is atomic structure linked to radioactivity & nuclear stability? How is radioactivity linked to the production of nuclear energy? Radioactivity is the property of some atoms to spontaneously give off energy as particles or rays. The atoms that make up the radioactive materials are the source of radiation. The Bohr-Rutherford model of atomic structure describes it as having a nucleus at the center, containing protons (positively charged) and neutrons (no charge) with electrons (negative charge) moved around the nucleus in "orbits" or shells on the outside. Particles in the nucleus (nucleons), and the forces among them, affect an atom's radioactive properties. A delicate balance of forces among nuclear particles keeps the nucleus stable. Any change in the number, the arrangement, or energy of the nucleons can upset this balance and cause the nucleus to become unstable or radioactive. The amount of energy required to break up the nucleus into its parts is called the binding energy, this is the same amount of energy given off when the nucleus formed. An atom that has an unbalanced ratio of neutrons to protons in the nucleus seeks to become more stable. The unbalanced or unstable atom tries to become more stable by changing the number of neutrons and/or protons in the nucleus. This can happen in several ways: converting neutrons to protons converting protons to neutrons Ejecting an alpha particle (two neutrons and two protons) from the nucleus. In changing the number of nucleons (protons and neutrons), the nucleus gives off energy in the form of ionizing radiation. The radiation can be in the form of alpha particles (2 protons and 2 neutrons), beta particles (either positive or negative), x-rays, or gamma rays. Radioactivity is when some atoms will spontaneously give off energy in the form of particles or rays do to their unstable nucleus. A change in the arrangement, energy or number of nucleons will make the nucleus unstable and the atom radioactive. The atom tries to regain its stability by changing the number of protons/neutrons in the nucleus and releasing energy. This energy is called nuclear or atomic energy. 4 Radioactivity is when some atoms will spontaneously give off energy do to their unstable nucleus. The unstable nucleus is usually due to an unbalance of neutrons and protons. In the processes to re-establish stability energy is given off. This is called nuclear or atomic energy. Radioactivity is when an atom has an unstable nucleus. The unbalanced atom tries to become more stable and this process gives off energy. 2 Radioactivity is when energy is given off when an isotope like C4 changes to a more stable atom like N4 and gives off energy in the process. Response is incoherent or irrelevant. PART B: Explain which nuclear process, fission or fusion, is used in the production of nuclear energy using U- 2? U-2 produces nuclear energy by fission where a neutron is propelled at a uranium atom splits it releasing heat and more neutrons that will bombard and split other uranium nuclei. Fusion is the opposite process, like what occurs in the sun, where two nuclei fuse and the lost mass converts to energy. 4 U-2 produces nuclear energy by fission where a neutron is propelled at a uranium atom, splits it releasing heat and more neutrons that will bombarding and splitting other uranium nuclei. U-2 produces nuclear energy fission because the uranium atom splits and produces energy. 2 U-2 produces nuclear energy fission. OR The uranium atom splits and produces energy. [Writes down elements that are somewhat useful for the completion of the task] Student incorrectly identifies the process. Environmental Science & Technology Secondary Cycle II Year II Page

2 C.: Use of appropriate scientific terminology, C2.2: Appropriate use of scientific and models and theories PART C: Calculate the average atomic mass of uranium. Round your answer to the nearest hundredth. Isotope Natural Abundance (%) Relative Mass U = U =.692 U = Total a.m.u concept and mathematical formalism systematically to solve the problem. Observes the conventions of efficient tools to represent concept and mathematical formalism but makes minor errors in the process. Observes most of the rules and conventions of adequate tools to represent Uses incorrect scientific concept or makes major errors in the mathematical process. Uses inappropriate types of representation without following Environmental Science & Technology Secondary Cycle II Year II Page 2

3 Question 2: In your opinion, which source of energy production contributes the least to the ecological footprint of Canadians? Your answer should consider: Soil depletion Ecological disturbances Greenhouse gas contribution Biodiversity Water or soil contamination Amount of energy produced Geological timeline /Sustainability/ Biodegradation The answers below cannot be considered full level fives as student expression and the way they related the material to ecological footprint is significant in that level of achievement. A student who has not defined ecological footprint in their text should not be at a level five for their competency 2. As a level five student should also consider the pros and cons in their argument I have highlighted these in the texts below. Please keep in mind that student answers will vary and to use professional judgment when considering what they have learned in class. Fossil Fuels should not be considered a valid answer for this question. Hydroelectricity: Hydroelectricity is a sustainable/renewable source of energy as it depends on the water flow from one part of a waterway to another. It is the kinetic energy from the moving water which is converted to electrical energy by electrical generators. When considering its role in our ecological footprint however, it should be noted that hydroelectricity does produce a small amount of GHGs, although they are no where as significant the amount of GHGs produced by fossil fuels or the burning of biomass. Also the ecological disturbances cause by the flooding as well as the subsequent mercurywater contamination that makes its way into the food chain and lasts up to 0 years in some fish species. The buildings of Hydroelectric dams have also been known to affect biodiversity because they disrupt spawning and other migratory patterns of some aquatic species. Biomass/Biofuels: Although biofuels, like fossil fuels produce large amounts of GHGs, the absence of sulfur lowers the creation of acid rain which is responsible for some ecological disturbances as well as water and soil contamination. Furthermore, biofuels are biodegradable which means that they will be broken down into useful elements to the ecosystems within a reasonable amount of time. They are not, however, the perfect solution. Soil depletion can be attributed the monoculture of certain usable crops which constantly need the same elements from the soil. Fertilization can rectify this problem but the fertilization process may lead to other ecological disturbances such as eutrophication if excess fertilizer finds itself in neighbouring bodies of water. Furthermore, biofuels are having an effect on biodiversity as deforestation is occurring to liberate land to grow the crops which affects the whole fauna population.. Nuclear Energy: A substantial amount of energy can be made from a small amount of uranium. However, the uranium needs to be mined which will create a large ecological disturbance by disrupting animal habitats and ecosystems in order to exploit this resource. Nuclear energy does not produce GHGs but does produce radioactive waste that has a long half-life and cannot be easily disposed of. In some cases, the waste has leaked into water systems as the reactors are rinsed with water to cool them disrupting the aquatic ecosystem. Nuclear energy is also not sustainable as it is a non-renewable resource because there is a limited amount of U-2 world wide. Rubrics on the next page Environmental Science & Technology Secondary Cycle II Year II Page

4 Competency Suitable justifications of explanations, solutions, decisions or opinions Justifies his/her explanation/tentative opinion on the basis of his/her scientific knowledge. Enriches explanations with elements that are complementary to the key concepts associated with the issue. Provides explanations or defends his/her opinions on the basis of scientific principles going beyond the explicitly stated aspects of the issue. Ultimately identifies positive and negative consequences related to the issue examined. Formulates a set of questions that makes it possible to identify the essential aspects related to the issue and its context. Establishes relevant connections between the issue and scientific principles involved. Produces coherent explanations by using theories and models of science and technology. Ultimately identifies realistic consequences related to the issue examined. Formulates a set of questions that covers some of the essential aspects of the issue. Establishes connections among the theories and models involved, only when obvious. Produces partial explanations. Ultimately identifies consequences related to the issue examined. Proposes an unfounded explanation or provisional opinion. Establishes connections that are more or less relevant between the issue and the concepts. Ultimately produces a rough draft of an explanation. Formulates a set of questions focused exclusively on secondary elements. Retranscribes verbatim information connected to the issue. Ultimately expresses unfounded opinions. Competency 4 2 Accurate interpretation of scientific and messages Accurately interprets the information in the message. Selects the elements appropriate for completing the task. Decodes information in the message. Transcribes information in the message to be interpreted. Does not identify relevant information. Appropriate production or sharing of scientific messages Uses complementary elements to enhance the quality of communication. Uses everyday language in order to make his/her messages easier to understand and interpret. Uses vocabulary that surpasses expectations, while observing the rules and conventions for all types of representation. Chooses efficient methods of representation. Correctly organizes the elements of his/her message, adapts it to the target audience and conveys it clearly. Uses terminology in accordance with the conventions in use. Uses appropriate types of representation, drawing on information and communications technologies, as needed, to present data in tables, graphs or diagrams. Organizes and partially adapts the elements of his/her message. For the simpler concepts, uses vocabulary in accordance with rules and Chooses acceptable types of representation to present Produces a message by juxtaposing its elements without adapting them to their target audience. Uses basic vocabulary or methods of representation that are largely inconsistent with Presents a limited number of elements, which makes it difficult to understand the message Uses familiar vocabulary or types of representation, without following Environmental Science & Technology Secondary Cycle II Year II Page 4

5 C.: Use of appropriate scientific terminology, C2.2: Appropriate use of scientific and models and theories Question : Describe quantitatively (in grams) how much more carbon dioxide is released by a Honda Civic with a motor of 0 KW that travelled for hour that uses Petroleum than one that uses Bioethanol. Hints: P t =E (Joules) Convert to KJ Table 2 provides the ratio to convert KJ to grams (cross multiplication) The chemical reactions are described in section 4: Combustion of fossil fuels Both chemical equations must be balanced before using stoichiometry P(w) t (sec) =E (Joules) = E (Joules).78 X 0 8 J = E.78 X 0 KJ = E PETROLEUM.78 X 0 KJ = 4.6 KJ x g g.78 X 0 = 4.6 x x = g mm C8H8 = 8 (2) + 8 () = 4 g/mol mol C8H8 = /4 = 76. mol 2C8H8 +2O2 6CO2 + 8H2O + energy mol C8H8 :molco2 2 : : mol = x 44 g/mol (608.8)(44) = g = g CO2 BIOETHANOL.78 X 0 KJ = 27. KJ x g g.78 X 0 = 27. x x = 846. g mm C2HOH =2 (2) + 6 () + (6) = 46 g/mol mol C2HOH = 846./46= 0 mol C2HOH + O2 2CO2 + H2O + energy mol C2HOH :molco2 : 2 0 : mol = x 44 g/mol (602.0)(44) = g The Honda Civic produces g more carbon dioxide when it burns petroleum than when it burns bioethanol. Uses the correct scientific concept and systematically to solve the problem. Observes the conventions of efficient tools to Uses the correct scientific concept and but makes minor errors in the process. Observes most of the conventions of adequate tools to Uses incorrect scientific concept or makes major errors in the mathematical process. Uses inappropriate types of representation without following rules and Environmental Science & Technology Secondary Cycle II Year II Page

6 C.: Use of appropriate scientific terminology, C2.2: Appropriate use of scientific and concepts, laws, models and theories Question 4: Circuit burned kg of natural gas (see Table 2) for 4 minutes in order to power the circuit. The reading on ammeter T is X0 2 A. Missing Information AT= 00 A VT = 000 V A= 20 A V = 000 V A2 = 40 A A = 40 A V2 = 000 V V = 000 V Work / Calculations: x KJ =.6 KJ 000g g OPTION OPTION 2 = + + _ Req x = (.6)(000) = 2.8 X 0 KJ = 2.8 X 0 8 J P t = E P = E/t =2.8 X 0 8 / (4 60) = 2.8 X 0 8 / 280 =.0 X 0 w P = I V.0 X 0 =.0 X 0 2 V V =.0 X 0 volts = _ = Req Req = 0/ =0 Ω VT = IT Req VT = 00 0 VT= 000 V Kirchhoff s law VT = V =V2 =... Kirchhoff s law VT = V =V2 =... I = V/R I = 000 / 0 = 20A I = V/R I = 000 / 0 = 20A I2 = V2/R2 I2 = 000 / 2 = 40A I2 = V2/R2 I2 = 000 / 2 = 40A I = V/R I = 000 / 2 = 40A I = V/R I = 000 / 2 = 40A concept and systematically to solve the problem. Observes the conventions of representation. Chooses efficient tools to represent concept and mathematical formalism but makes minor errors in the process. Observes most of the rules and conventions of adequate tools to represent Uses incorrect scientific concept or makes major errors in the mathematical process. Uses inappropriate types of representation without following rules and Environmental Science & Technology Secondary Cycle II Year II Page 6

7 C.: Use of appropriate scientific terminology, C2.2: Appropriate use of scientific and models and theories Circuit 2 was powered by.7 mg of uranium-2 (see nuclear energy section) for 00 seconds and its power source has a potential difference 20 times greater than the potential difference of the power source of circuit. When calculating the amount of energy from the uranium make sure to convert to moles. Missing Information V = 000 V V 2 = 700 V V = 000 V V 4 = 200 V V T = V A = 00 A A 2 = 00 A A = 00 A A 4 = 00 A R = 0 Ω Work / Calculations:.7 mg /000 = 0.07g.7 X 0-2 g = X 0-2 g/mol x KJ = 2 X 0 0 KJ x = (2 X 0 0 )( X 0 - ) = X 0 6 KJ = X 0 9 J X 0 - mol mol P t = E P = E/t = X 0 9 / (00) = X 0 9 / 00 = w V = = V P = I V = I I = 00 A Kirchhoff s law IT = I =I2 =... V = IR V = I R V2 = I2 R2 V = I R = 00 0 =000 v = 00 7 =700 v = 00 2 =200 v Kirchhoff s law VT = V + V2+ V +... VT V V2 V4 = V V = = 000 v V/I = R R = 000 / 00 = 0 Ω Uses the correct scientific concept and systematically to solve the problem. Observes the conventions of efficient tools to concept and but makes minor errors in the process. Observes most of the conventions of adequate tools to Uses incorrect scientific concept or makes major errors in the mathematical process. Uses inappropriate types of representation without following Environmental Science & Technology Secondary Cycle II Year II Page 7

Chapter 12: Nuclear Reaction

Chapter 12: Nuclear Reaction A nuclear reaction occurs when a nucleus is unstable or is being bombarded by a nuclear particle. The product of a nuclear reaction is a new nuclide with an emission of a nuclear