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Transcript
Name: _________________________ Period: ________________________ Chapter 6 Study Guide: Thermal Energy Part A: Match the terms on the left with the explanations and situations on the right. Some answers may be used more than once and some may not be used at all. A. method of heat transfer where particles collide 1. Heat flow B. heat flows slowly in this type of material 2. Convection 3. Thermal Energy 4. Conduction 5. Radiation C. the air temperature is greatest at the top of a staircase because of this D. the increase in thermal energy of the system equals work done on the system plus the heat transferred to the system E. difference between materials that absorb the same amount of heat with different changes in temperature F. unit for heat energy/thermal energy 6. Temperature G. heat energy from the sun is absorbed by a blade of grass 7. Specific Heat H. unit for temperature 8. Joule 9. Closed System 10. Kelvin I. the total energy remains constant between all objects in the group J. this will not spontaneously occur from a lower temperature to a higher temperature K. a measure of average KE (doesn’t depend on mass) 11. Insulator L. KEtotal + PE 12. First Law of Thermodynamics Part B: True or False – Write TRUE or FALSE beside each statement. If I can’t read it, it’s wrong! 1. A 2-kg beaker of water has a temperature of 15°C. If 2 more kg of water at 15°C are added, the temperature becomes 30°C. 2. Thermal Energy only moves from particles at a lower temperature to particles at a higher temperature. 3. Friction converts thermal energy into mechanical energy. 4. Heat cannot spontaneously flow from a cool object to a warm object. 5. The thermal energy of an object decreases when some of its mass is removed because thermal energy depends on the total kinetic energy of all the particles. 6. Work can be completely converted into heat, but heat cannot be completely converted into work. 7. Water is used as a coolant because it has a very low specific heat, meaning it changes temperature quickly when a small amount of heat is added. 8. A refrigerator does work to move heat from a cooler temperature to a warmer temperature by using a coolant. Part C: Short Answer – Write a few sentences to answer each of the following. You may draw a picture along with your answer, but make sure you write an explanation. 1. A horseshoe is heated in a fire. a. Explain why it is easier to bend when it’s hot. b. Explain why water is used to cool the horseshoe. 2. a. Describe the heating process when a beaker of water is heated from the bottom. b. Describe the heating process when a beaker of water is heated from the top. 3. A beaker holds 30 mL of water at 22℃. Another beaker holds 30 mL of water at 22℃. Both volumes of water are added together. a. What is the final temperature of the 60 mL volume of water? b. What is “temperature”? 4. One summer day, your friend decides to leave the refrigerator door open too cool off the kitchen. After a few hours, would this work or not? Using all your knowledge of heat movers, explain your reasoning. Part D: Fill in the blank with the appropriate word or phrase, or label where appropriate. Refer to the pictures above each item and use the following terms. (not all will be used) Work Conduction Thermodynamics Mass Solid Gas Temperature Convection Thermal Energy Radiation Kinetic Liquid 1. The arrows represent the velocity of each particle. Particles are of the same substance. The cube on the right has the same _______________ as the cube on the left. However, the cube on the right has more particles and more _______________. (a) (b) (c) 2. These diagrams are of particles of different states of matter. Diagram A represents _______________ particles because they are spaced far apart and have high kinetic energy. Diagram B represents _______________ particles because they are closer together but still able to move freely. Diagram C represents _______________ particles because they are tightly packed and vibrate at lower velocities than the other two. 3. The above picture represents 3 methods of heat transfer. Label each. (hint: the arrows for one are not shown – draw it!) 4. Discuss each method of heat transfer (hint: use your concept map). 5. What are three common temperature scales? Compare freezing and boiling of these scales. Part E: Problems – Use the temperature conversion equations and the thermal energy equation to solve the problems in this section. Partial credit will be given for setting up the problem correctly, even if the answer is wrong, so TRY! 1. An ice cube has a temperature of -5°C. What is its temperature on the Kelvin scale? 2. A mass of 0.50-kg of water at 25°C is in a pot on a stove. The stove is turned on and the temperature of the water rises to 84°C. The specific heat of water is 4,184 J/kg°C. What amount of heat energy did the water gain? 3. The pot in problem 2 starts at a temperature of 25°C and has a mass of 1-kg. It is made of copper, which has a specific heat of 385 J/kg°C. How much heat energy is needed to get it to the same final temperature as the water (84°C)? 4. A substance at 73°C has a mass of 8.4 kg. Its specific heat is 710 J/kg°C. What is the temperature of the substance after 73,000 J of thermal energy have been added? 5. Use the chart on pg. 185. A substance has a mass of 0.128-kg and a temperature of 84°C. When it is placed in 0.056-kg of water at 23°C, the water absorbs its heat energy until the substance and the water both reach a temperature of 30°C. The specific heat of water is 4,184 J/kg°C. Find the specific heat of the other substance and name it. Hint: this is what you did in the specific heat lab!