Study Guide Unit 3 Chapter 6 DRAFT

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1 Study Guide Unit 3 Chapter 6 DRAFT

2 Unit 3 BIG IDEAS Energy can be transformed from one type into another. Energy transformation systems often involve thermal energy losses and are never 100 % efficient. Although technological applications that involve energy transformations can affect society and the environment in positive ways, they can also have negative effects, and therefore must be used responsibly. Energy and Society Chapter 5 Work, Energy, Power and Society Work, energy, and power are related concepts that affect everyday life, society, and the environment. In science, energy is defined as the capacity to do work. There are many types of energy and they can all be categorized as potential energy, kinetic energy, or a combination of both. The law of conservation of energy states that the total amount of energy in the universe does not change. Energy cannot be created nor destroyed, but it can be transformed. Power is the rate at which energy is transformed; efficiency quantifies the amount of useful energy produced when energy is transformed. The selection and use of renewable or nonrenewable energy resources have an impact on society and the environment. Chapter 6 Thermal Energy and Society Thermal energy, temperature, and heat are similar concepts, but these terms are not interchangeable. Thermal energy is the total amount of potential and kinetic energy possessed by the particles of a substance. Temperature is the average kinetic energy of the particles. Heat is the term used to describe the transfer of thermal energy. Change in the thermal energy of a substance can cause changes of state, such as melting or freezing. Heating and cooling systems, which keep homes, schools, and businesses comfortable, are familiar applications of thermal energy, temperature, and heat. These systems can have both positive and negative impacts on the environment. Chapter 7 Nuclear Energy and Society Nuclear energy is released during changes in the structure of atomic nuclei. Some forms of atoms, called isotopes, change spontaneously, releasing energy called radiation. This process has practical applications, such as carbon-14 dating and medical diagnosis. There are several different types of radioactive decay reactions Very large amounts of energy are released in fission reactions, making nuclear fission a useful energy source. However, there are safety and waste disposal issues related to the use of nuclear fission as a power source. Nuclear fusion, which is the source of energy for the Sun and other stars, is a reaction in which the nuclei of two atoms fuse and a great amount of energy is released. Nuclear fusion is better than nuclear fission from an environmental standpoint, but it is very difficult to achieve. At present it is not a practical source of energy. Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Overview

3 6.1 Textbook pp Warmth and Coldness Vocabulary kinetic molecular theory Fahrenheit scale freezing point thermal energy Kelvin scale boiling point temperature melting point condensation point Celsius scale Main idea: Thermal energy is the total potential energy and the total kinetic energy possessed by the particles of a substance. 1. The SI unit used to measure thermal energy is the. [K/U] 2. The thermal energy of a substance includes both the and the of the particles of the substance. [K/U] 3. The of the particles of a substance is associated with the motion of the particles. [K/U] 4. The of the particles of a substance is associated with the force of attraction between the particles. [K/U] Main idea: Temperature is a measure of the average kinetic energy of the particles in a substance. 5. Compare and contrast the thermal energy of a substance and the temperature of the substance. [T/I] [C] Main idea: The kinetic molecular theory states that as particles of matter gain kinetic energy, they move faster and the temperature of the substance increases. Similarly, as particles of matter lose kinetic energy, they move more slowly and the temperature of the substance decreases. 6. Fill in the flow chart below using the words increases and decreases to describe the relationship between temperature of a substance and the kinetic energy of the particles of the substance. [K/U] [C] STUDY TIP Flow Charts You can use flow charts to summarize and order the steps in a process. gain kinetic energy speed of their motion temperature of the matter particles of matter lose kinetic energy speed of their motion temperature of the matter Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 1

4 Main idea: Temperature can be measured using the Celsius scale, Fahrenheit scale, or Kelvin scale. Scientists typically use the Kelvin scale because kelvins are SI units. 7. Fill in the blanks below to describe the Fahrenheit and Celsius scales. [K/U] Celsius scale Created by: Boiling point of pure water: Freezing point of pure water: Fahrenheit scale Created by: Boiling point of pure water: Freezing point of pure water: 8. Describe the motion of particles in a substance at absolute 0, or 0 K. [K/U] Main idea: The equations T C = T K 273 and T K = T C can be used to convert temperatures from one scale to the other. 9. Fill in Table 1 below to practise converting temperatures from one scale to another. [T/I] Table 1 Temperature Conversions Celsius Kelvin (a) 45 C (b) 120 K (c) 12 C Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 2

5 6.2 Textbook pp Heat Vocabulary heat convection current thermal conductor thermal conduction radiation thermal insulator convection Main idea: Thermal energy is the total amount of kinetic energy and potential energy of the particles in a substance. 1. What two types of energy make up the thermal energy of a substance? [K/U] 2. The thermal energy in the particles of a substance determines the of the substance. [K/U] 3. Two objects of the same mass and the same material that have the same thermal energy will have the same. [K/U] 13. Fill in the missing terms in the concept map below to describe the relationship between changes in thermal energy and changes in temperature. [T/I] STUDY TIP Concept Maps You use a concept map to the describe relationships between processes. When a substance absorbs energy, some of the energy increases the energy of the particles increases the energy of the particles which which increases the temperature of the object does not increase the temperature of the object 14. As described in the flow chart above, the energy that a substance absorbs changes both the potential energy and the kinetic energy of the particles of the substance. Is the percentage of the added energy that changes kinetic energy and the percentage of the added energy that changes potential energy the same for all substances, or does it vary between substances? [K/U] Main idea: Heat is the transfer of thermal energy from a warmer object to a cooler one. 15. Contrast the meaning of the terms heat and thermal energy. [K/U] [C] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 3

6 Main idea: Thermal energy can be transferred in three different ways: by thermal conduction, by convection, or by radiation. 16. Fill in Table 1 below to describe conduction, convection, and radiation. [K/U] Table 1 Thermal Energy Transfer Type of thermal energy transfer Definition Everyday example conduction convection radiation 17. Define each of the following terms in your own words and provide one example of each. [K/U] (a) A thermal conductor is One example of a good thermal conductor is. (b) A thermal insulator is One example of good thermal insulator is. Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 4

7 6.3 Textbook pp Heat Capacity Vocabulary specific heat capacity (c) principle of thermal energy exchange thermal contraction quantity of heat (Q) thermal expansion Main idea: Specific heat capacity is the amount of heat needed to raise the temperature of a 1 kg sample of a substance by 1 C. Table 1 Specific Heat Capacities of Common Substances Substance water ethyl alcohol ice aluminum glass iron copper silver lead Specific heat capacity (J/(kg C)) 1. Suppose 10 J of energy is added to 0.1 kg of each substance shown in Table 1 above. [T/I] (a) Which substance will experience the greatest change in temperature? (b) Which substance will experience the least change in temperature? (c) Explain the reasoning you used to arrive at your answers for parts (a) and (b). Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 5

8 LEARNING TIP Units of Mass in the Heat Equation Since the units for specific heat capacity are joules per kilogram per degree Celsius, mass must be expressed in kilograms when using the quantity of heat equation. Main idea: The quantity of heat, or amount of thermal energy absorbed or released by an object, can be calculated using the equationq= mc T. 2. For each variable in the equation Q= mc T, identify the meaning of the variable and the units used. [K/U] (a) Q stands for ; measured in units of. (b) m stands for ; measured in units of. (c) c stands for ; measured in units of. (d) ΔT stands for ; measured in units of. 3. A block of iron with a mass of 23 kg is heated from 25 C to 65 C. How much thermal energy is absorbed by the iron? Use the space below for your calculations. [T/I] STUDY TIP Showing your work Showing each step in a calculation can help you eliminate errors in your work. 4. A sample of water is cooled from 82 C to 75 C, releasing J of energy into the air around it. Determine the mass of the sample of water. Use the space below for your calculations. [T/I] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 6

9 Main idea: The principle of heat exchange states that thermal energy moves from a warm object to a cooler one until both objects reach a new constant temperature. This principle can be represented by the equation Q released + Q absorbed = Does the equation Q released + Q absorbed = 0 reflect the law of conservation of energy? Explain why or why not. [T/I] [C] 6. What assumption is made when using the equation Q released + Q absorbed = 0 to describe thermal energy exchange? Is this assumption realistic in everyday settings? [T/I] [C] Main idea: The absorption or release of thermal energy results in thermal expansion or contraction. 7. An increase in the thermal energy of a substance causes the particles to spread out, resulting in. [K/U] 8. A decrease in the thermal energy of a substance causes the particles to move closer together, resulting in. [K/U] 9. Identify an everyday object that has been designed to accommodate thermal expansion and contraction, and describe specifically how the object s design allows for thermal expansion and contraction. [T/I] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 7

10 6.4 Textbook pp States of Matter and Changes of State Vocabulary fusion latent heat (Q) specific latent heat (L) heating graph latent heat of fusion specific latent heat of fusion (L f ) cooling graph latent heat of vaporization specific latent heat of vaporization (L v ) Main idea: The three states of matter are solid, liquid, and gas. When thermal energy is released or absorbed a change in state may happen. 1. Label the states of matter in Figure 1 below. [K/U] Figure 1 2. Complete the statements to describe what happens in the Figure 2 below. Use the terms increases, decreases, or remains unchanged to fill in the blanks. [T/I] Figure 2 Between (a) and (b), thermal energy and temperature. Between (b) and (c), thermal energy and temperature. > Between (c) and (d), thermal energy and temperature. Between (d) and (e), thermal energy and temperature. 3. In some of the descriptions above, thermal energy increased, yet temperature Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 8

11 remained unchanged. How can this occur if energy is conserved? [T/I] Main idea: The change in temperature that occurs as a substance releases or absorbs thermal energy can be shown in a cooling graph or a heating graph. Use Figure 3 to complete questions 4 and 5. STUDY TIP Line Graphs Line graphs can be used to show how a change in one variable is associated with a change in another variable. Figure 3 4. The vertical dotted lines in Figure 3, divide the graph into five sections, from left to right. Mark an X on any section that represents a change of state. [T/I] 5. If the y-axis of the graph above was labelled Thermal Energy rather than Temperature, would the line have the same shape? Explain. [T/I] Main idea: The thermal energy that is absorbed or released during a change of state is called the latent heat of the substance. If the substance is melting or freezing it is called latent heat of fusion. If the substance is evaporating or condensing, it is called the latent heat of vaporization. 6. What is the SI unit for latent heat? [K/U] 7. Latent heat of fusion is the amount of energy absorbed when a substance or released when a substance. [K/U] 8. Latent heat of vaporization is the amount of energy absorbed when a substance or released when the substance. [K/U] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 9

12 LEARNING TIP Remember Units As with all questions in physics, make sure the units in your calculations of latent heat match. Mass must by expressed in kilograms, and latent heat is expressed in joules since the units for specific latent heat are joules per kilogram. Main idea: The specific latent heat of fusion (L f ), is the amount of thermal energy per kilogram needed to melt or freeze a substance. The specific latent heat of vaporization (L v ), is the amount of thermal energy needed per kilogram to evaporate or condense a substance. 9. For any specific substance, explain why a single value can be used for both the latent heat associated with melting and the latent heat associated with freezing. [K/U] Main idea: The equation Q= ml is used to calculate the latent heat of fusion, and Q= ml v f is used to calculate the latent heat of vaporization. 10. How much thermal energy is released by a 24 g ice cube as it melts? The specific latent heat of fusion of water of water is J/kg. Use the space below for your calculations. [T/I] Main idea: Ice is one of the few solids that floats in its liquid; this is due to the shape of its molecules and the forces of attraction between its molecules. 11. Temperature of a sample of water changes from 20 C to 0 C. What happens to its volume? [K/U] 12. Describe one practical consideration that must be considered related to your answer to question 11. [T/I] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 10

13 6.5 Textbook pp Heating and Cooling Systems Vocabulary electrical heating system hot water heating system forced-air heating system geothermal system Main idea: All heating systems have a source of thermal energy, a means of transferring the energy, and a thermostat to control the production and distribution of energy. Conventional heating systems use either electricity or fossil fuels as a source of thermal energy. 1. Compare and contrast forced-air heating systems and hot water heating systems. Identify one way they are similar and one way that they are different. [K/U] STUDY TIP Cycle Diagrams You can use a cycle diagram to learn about a process that occurs in a series of repeating steps. Main idea: Conventional cooling systems use the evaporation of pressurized refrigerants to absorb thermal energy from the air, resulting in cool air that can then be blown through a duct system. 2. Fill in the cycle diagram below to describe how cooling systems work. Use the following sentences to fill in the cycle diagram. [K/U] Warm refrigerant gas releases thermal energy and changes to a liquid. Liquid refrigerant evaporates into a gas. Liquid refrigerant absorbs thermal energy from surroundings. Temperature of refrigerant gas increases. Refrigerant gas is compressed. Liquid refrigerant passes through an expansion valve. Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 11

14 Main idea: A typical thermostat uses a bimetallic strip and a mercury switch to turn a heating or cooling system on or off as temperatures change. 3. Use the concepts of thermal expansion and contraction to explain why a bimetallic strip, rather than a strip made of a single type of metal, is used in many thermostats. [T/I] [A] Main idea: Conventional heating and cooling systems produce greenhouse gases such as carbon dioxide, so they are not considered environmentally friendly. 4. Identify one specific way in which conventional heating systems can damage the environment, and one specific way in which conventional cooling systems can damage the environment. [K/U] [C] Main idea: Geothermal systems use Earth s natural thermal energy for heating and cooling purposes. In the winter thermal energy is transferred from below Earth s surface into a building to heat it. In the summer, thermal energy is transferred from a building into Earth s surface to cool it. 5. Is the following statement true or false? If you think the statement is false, rewrite it to make it true: In a geothermal system, thermal energy in Earth s crust is used to heat and cool homes. [K/U] 6. During the winter, temperatures underground are than those above ground. In the summer, the temperatures underground are than those above ground. [K/U] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 12

15 6.6 Textbook pp Explore an Issue in Thermal Energy Geothermal Systems: Friend or Foe? Main idea: Geothermal heating and cooling systems are promoted as an environmentally safe alternative to using fossil fuels, but geothermal systems have risks of their own. 1. Through your research, what did you find to be the benefits, and risks and costs of geothermal systems? Record your findings in Table 1. [T/I][C] Table 1 Geothermal Systems Benefits Risks and Costs STUDY TIP T-Charts You can use a T-chart to organize and compare information you find during research. 2. Based on what you have learned in your research, do you think the benefits of geothermal systems outweigh the risks and costs? Explain. [T/I] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 13

16 6.7 Textbook pp Physics Journal When a Brewer Becomes a Scientist Main idea: Often, scientific breakthroughs and understanding are the result of practical interest. 1. How Did Joule s love of science first develop? [K/U] 2. Were Joule s early results well received by the scientific community? Why or why not? [K/U] 3. Describe the understanding of thermal energy that most scientists of Joule s time shared. [K/U] STUDY TIP Questioning Questions about a reading passage can be used to help you understand the main ideas. 4. How did Joule s understanding of thermal energy differ from the prevailing scientific idea of his time? [K/U] 5. How did Joule demonstrate that mechanical energy could be transformed into thermal energy? [K/U] 6. Was Joule s work eventually accepted? Explain. [K/U] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 14

17 Chapter 6 Summary Thermal Energy and Society Matter made up of particles can change states when thermal energy is which have absorbed or released kinetic energy average kinetic energy thermal energy (total kinetic + potential energy) the transfer of which is called heat expressed as a temperature on the Celsius scale Fahrenheit scale Kelvin scale Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 15

18 Chapter 6 Questions K/U Knowledge/Understanding For each question, select the best answer from the four alternatives. C T/I A Communication Thinking/Investigation Application 1. At which temperature do the particles of a substance have the least kinetic energy? (6.1) [K/U] K/U (a) 212 F (b) 100 C (c) 100 K (d) 273 C 2. Which of the following is classified as a thermal conductor? (6.2) [K/U] (a) wool (b) copper (c) air (d) plastic Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true. 3. The specific heat capacity of water is high in comparison to most common liquids. (6.3) [K/U] 4. The particles of an ice cube have greater kinetic energy than the particles in a cup of liquid water. (6.4) [K/U] Respond to each statement or answer each question below. 5. You taste a bit of soup, and it burns your tongue. You set the soup aside for several minutes, and then taste the soup again. Now it can be eaten. Explain what has occurred in terms of the kinetic energy of the particles of the soup. (6.1) [T/I] [A] 6. Compare the thermal energy and temperatures of the following two samples of water: Sample A is 0.5 ml, and Sample B is 100 ml. The particles in each sample have the same kinetic energy. (6.2) [T/I] [A] 7. Identify one benefit of geothermal systems and one risk or cost of geothermal systems. (6.6) [T/I] 8. Three qualities that many scientists possess are curiosity, perseverance, and independent thinking. Choose one of these qualities, and describe how that quality was displayed by James Prescott Joule. (6.7) [T/I] Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 16

19 9. Fill in the blanks with the term that best represents following temperatures. (6.1) [K/U] (a) temperature at which liquid change to gas: (b) temperature at which solid changes to liquid: (c) temperature at which gas changes to liquid: (d) temperature at which liquid changes to solid: 10. Complete the concept map below with the terms convection, radiation, and conduction. (6.2) [K/U] [C] which is the transfer of thermal energy through a fluid when colder, denser fluid falls and pushes up warmer, less dense fluid Thermal energy can be transferred by which is the transfer of thermal energy that occurs when objects are in physical contact which is the movement of thermal energy as electromagnetic waves 11. Fill in the flow chart below, describing what happens as the temperature of a sample of water is cooled from 110 C to -10 C. Use the following phrases to complete the flow chart: (6.4) [T/I] [C] water vapour condenses into liquid water liquid water cools down liquid water freezes into ice ice cools down water vapour cools down 110 C 10 C (a) (b) (c) (d) (e) Copyright 2011 by Nelson Education Ltd. DRAFT Unit 3 Chapter 6 17