1 Exploring Heat from the Basics of Physics Series Pre-Test

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1 1 Pre-Test A. Directions: Pick the definition in column B that best matches the word in column A. Write the letter of the definition on the blank line. A B 1. convection 2. radiation 3. conduction 4. heat 5. temperature 6. Celsius 7. Kelvin 8. Fahrenheit 9. calorie 10. calorimeter a. A temperature scale based on absolute zero. b. The transfer of heat energy through direct contact. c. A temperature scale based on the freezing and boiling point of water. d. A device used to calculate the amount of heat energy stored in food. e. The transfer of heat energy through the emptiness of space. f. The transfer of heat energy through a liquid or gas. g. The measure of how hot or cold something is. h. The amount of energy needed to change the temperature of one gram of water one degree celsius. i. Energy that is based on the temperature and mass of an object. j. A temperature scale based on the freezing point of water at 32 degrees. B. Directions: Answer the following questions with a short answer. 1. Describe the water cycle and the importance of the sun's radiant energy in that cycle. 2. Wires between telephone poles sag. Why aren't they pulled tight? 3. Heat and temperature are not the same thing. How are they different? 4. How does a thermometer work? 5. What is a change of phase, or state?

2 2 Program Quiz _ Part A: Identify if the following situations are examples of heat transfer by conduction, convection, or radiation. Circle your answer. 1. The spoon is too hot to touch after sitting in the hot soup. (conduction, convection, or radiation) 2. The moon's surface becomes hot. (conduction, convection, or radiation) 3. Your feet hurt after walking barefoot across the beach. (conduction, convection, or radiation) 4. Bacon cooks in the frying pan. (conduction, convection, or radiation) 5. The room becomes warm when the furnace is turned on. (conduction, convection, or radiation) Part B: Short Answer 1. Sidewalks are built with spaces between each section. Why? 2. The cap on the jar is stuck, but if we run it under hot water we can unscrew the metal cap. Why? 3. The level of the water in the aquarium goes down each day. Why?

3 3 Vocabulary Directions: Match the term in column A with its definition in column B. Column A 1. convection 2. conduction 3. radiation 4. heat 5. temperature 6. evaporation 7. kinetic energy 8. potential energy 9. absolute zero 10. calorie 11. calorimeter 12. btu 13. Fahrenheit 14. Celsius 15. Kelvin Column B A. Amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit. B. The measure of how hot or cold something is. C. The energy of position. D. The amount of energy needed to change the temperature of one gram of water one degree Celsius. E. The lowest possible temperature. F. The transfer of heat energy through the emptiness of space. G. The transfer of heat energy through direct contact. H. A temperature scale based on the freezing and boiling point of water. I. Energy that is based on the temperature and mass of an object. J. A temperature scale based on the freezing point of water at 32 degrees. K. The transfer of heat energy in a liquid or a gas. L. A device used to calculate the amount of heat energy stored in foods. M. The energy of motion. N. A temperature scale based on absolute zero. O. Vaporization of a liquid at the surface level and at a temperature below boiling.

4 4 The Motion of Particles _ Purpose: To demonstrate the motion of particles. Materials: 3 small beakers ice cube dark food coloring 2 medicine droppers hot water Procedures: 1. Fill a small beaker about 2/3 full of water at or near room temperature. 2. Place one drop of dark food coloring on the surface of the water. DO NOT STIR. Make observations below (observations 1 and 2). 3. Fill a second beaker about 2/3 full of water. Add an ice cube to the water. Leave it in the water for two or three minutes and then remove it. 4. Fill a third beaker 2/3 full of hot water. 5. Place the beakers side by side. 6. Wait a minute for the water currents to stop. Then add one drop of food coloring to each beaker at the same time. Make observations. Observations: 1. How does the food coloring behave in the beaker with room temperature water? 2. Write a hypothesis that tells what effect you think hot or cold water would have on the rate at which the coloring mixes. 3. In which beaker (hot or cold) are the water particles moving faster? 4. In which beaker did the mixing appear to take place faster? Conclusion: In your own words, explain your observations.

5 5 Temperature and Heat Purpose: To compare and contrast temperature and heat. Materials: two beakers (250 ml) alcohol lamp thermometer stirring rod ringstand and ring water Procedures: 1. Label one beaker A and fill it ¼ full of tap water. 2. Label the second beaker B and fill it about ¾ full of water. 3. Measure the temperature of the water in each beaker. Record this as the intial temperature (Ti). 4. Place beaker A on the ringstand. Light and adjust the lamp and place it under the ring. Heat the beaker and water for ONE minute. 5. After a minute, remove the beaker from the ringstand. Stir the water three or four times with a stirring rod. Measure the temperature and record as the final temperature (Tf). 6. Repeat steps 4 and 5 with beaker B. Remember, heat for exactly ONE minute. 7. Record the temperature change for each beaker. Observations: Beaker A Beaker B Initial Temperature Final Temperature Change Conclusion: 1. How did the temperature change in beaker A compare with the temperature change in beaker B? 2. How do the terms "temperature" and "heat" differ in meaning?

6 6 Homemade Thermometers _ Purpose: To challenge students to build two different types of homemade thermometers from the supplied materials. Materials: beaker with water one-hole rubber stopper (test tube size) test tube glass tube (should be more than nine inches long) Procedure: 1. Push one end of the glass tubing through the one-hole stopper. 2. Using the supplied materials, build a working thermometer. Once you have constructed a thermometer, show it to your teacher. 3. After building one thermometer, take it apart and build a different thermometer. There are two very different types of thermometers that can be made from these supplies. Observations: 1. Describe the two thermometers you made. 2. How are they different? Conclusions: Which thermometer works best? Why is it better?

7 7 Latent Heat Purpose: To determine how temperature is affected while a change of state is occurring. Materials: thermometer alcohol burner beaker water stirring rods ringstand ice paper to record data Procedures: Part A 1. Fill the beaker with ice. 2. Carefully put the thermometer in the ice mass. 3. Add enough water to the beaker to cover the bulb of the thermometer. 4. Stir very gently with the stirring rod and check the water temperature every 30 seconds. When the water has remained at 0 degrees for two minutes, ask to have your alcohol burner lit. 5. Record the temperature every 30 seconds and sketch how much ice remains each time. 6. After the ice has completely melted, continue recording the temperature for five minutes. Part B 1. Fill the beaker half way with water. Place it on the ringstand. 2. Ask to have your alcohol burner lit. 3. Heat the water and record the water's temperature every 30 seconds. 4. Continue recording the temperature as the water starts to boil. Record the temperature every 30 seconds for three more minutes. Observations: 1. Part A: Make drawings of the amount of ice left after every 30 second temperature reading. Make the drawings on a separate sheet of paper. Make a graph of the temperature readings for the melting ice. 2. Part B: Make a graph to show temperature readings every 30 seconds. Conclusion: What happens to the temperature of a substance going through a change of state?

8 8 Heat Movement Purpose: To determine whether heat travels from warm to cold or from cold to warm. _ Materials: two thermometers hot water cold water one large beaker one medium beaker Procedures: 1. Place hot water in the large beaker. 2. Place cold water in the small beaker. 3. Place a thermometer in each beaker. Record the two temperatures. 4. Set the small beaker inside the larger beaker. 5. Check both water temperatures after 10 minutes. 6. Record final temperatures. Observations: Starting Temperature Final Temperature Large beaker hot water Small beaker cold water Conclusion: Which way does the heat travel?

9 9 Different Materials Conduct Heat Purpose: To compare how different materials conduct heat. Materials: liquid crystal thermometer regular thermometer materials to test: styrofoam, cardboard, ceramic tile, glass, wood, metal, etc. Procedure: 1. Set the materials out on a table for about an hour before testing. 2. Use the regular thermometer to record the temperature of the room. 3. Touch each item being tested one at a time and determine if they feel warm or cold to the touch. 4. Use the liquid crystal thermometer to record the temperature of each test item. Observations: Test Item Temperature Conclusion: Which items are good conductors and which items are good insulators?

10 10 Heat Loss _ Purpose: To determine if aluminum foil can reduce heat loss. Materials: thermometers three flasks aluminum foil hot water Procedures: 1. Cover one flask with aluminum foil, shiny side out. 2. Cover a second flask with aluminum foil, shiny side in. 3. Leave the third flask uncovered. 4. Pour 75 ml of boiling water into each flask. 5. Take the temperature of the water in each flask. 6. Continue to take the temperature every five minutes for 30 minutes. Record temperatures on graph paper. Observations: Record temperatures for each flask on graph paper. Make readings every five minutes for at least 30 minutes. Conclusions: 1. Which flask had the greatest change in temperature? 2. Which flask retained the most heat? 3. What would your recommendation be for creating a container that conserves the most heat?

11 11 Ice, Sugar, Salt, and Methanol Purpose: To determine what effect sugar, salt, and methanol have on ice. Materials: thermometer 100 ml beaker stirring rod Procedures: 1. To establish the accuracy of your thermometer, take your beaker to the sink and fill it 1/3 full with crushed ice. 2. Insert the thermometer so its bulb settles in the center of the crushed ice mass and allow the temperature to stabilize for 2-3 minutes. Record below under "ice temperature." 3. Hypothesize what the effect of sugar will have on ice. Write the hypothesis here: 4. Mix ½ teaspoon of sugar with the ice and gently stir for one to two minutes. Lower the bulb of the thermometer into the ice mass and allow the temperature to stabilize for two to three minutes. Record the temperature under "ice and sugar." 5. Dump the beaker's contents into the sink and refill the beaker with 1/3 crushed ice. This time, measure ½ teaspoon of table salt. Hypothesize as to the effect this will have on the temperature of the ice: 6. Carefully pour the salt into the beaker and repeat the above. 7. One final time, dump and refill with fresh ice. This time, obtain 10 ml of methanol. Hypothesize as to what this liquid might do to the temperature of the ice: 8. Slowly pour the methanol over the crushed ice and stir gently. Record the temperature after two minutes. Observations: Make observations in the following chart. Ice Sugar and Ice temperature Salt and Ice Methanol and Ice Conclusion: In which situation was the temperature change the greatest?

12 12 Aluminum and Water _ Purpose: To determine which contains more heat: a mass of aluminum or an equal mass of water. Write a hypothesis here: Materials: thermometer two beakers alcohol burner ringstand graduated cylinder balance scale bolts with string attached two styrofoam cups Procedure: 1. Find the mass of the bolts. 2. Use the graduated cylinder to measure out an equal mass of water and pour it into one of the beakers. (1 ml = 1 gram of water) 3. Put the bolts into this beaker and heat to 80 degrees Celsius. 4. While heating, obtain 80 ml of tap water and measure its temperature. Split the 80 ml of water into the two cups. 5. When the bolts and water have reached 80 degrees, blow out the flame. Lift out the bolts using the string. 6. Put the bolts in one cup and pour the heated water from the beaker into the other cup. 7. Stir each cup for exactly one minute and then record the final temperature readings. Observations: Starting temperature Temperature after bolts or water added Cup of water Cup of bolts Conclusions: Which cup's temperature increased more? Which material contained more heat at 80 degrees Celsius?

13 13 Sense of Touch and Water Temperature Purpose: To determine how well we can use our sense of touch to determine the temperature of water. Materials: three cups hot water cold water room temperature water Procedures: 1. Pour cold water into one of the cups. 2. Pour hot water into another cup. 3. Pour room temperature water into the third cup. 4. Arrange the cups so the cold water is on one side and the hot water is on the other side of the cup with room temperature water. 5. Put one finger from one hand in the cold water. 6. Put one finger from the other hand in the hot water. 7. Keep the fingers submerged in the water for at least 30 seconds. 8. Quickly plunge the two fingers into the third cup which is filled with room temperature water. Observations: 1. What messages were being sent to your brain? 2. Did both fingers sense the same thing? Conclusion: Scientists had to develop instruments to help determine things like temperature changes because the human senses aren't always reliable. Can you explain why?

14 14 Measuring Heat Energy _ Purpose: To determine the amount of heat energy given off by various foods and other substances. Materials: cork thermometer needle test tube ring stand test tube clamp various substances, such as: bread, potato, paraffin, piece of wood, cloth Procedures: 1. Put 50 ml of water into the test tube and measure its temperature. 2. Take one of the substances being tested and stick it on the blunt end of the needle. Stick the needle in the cork so that the sample is sticking up. 3. Light the sample and let it burn. 4. Bring the test tube over the flame and hold it there until the flame goes out. 5. Measure the temperature of the water again. 6. A calorie is the amount of energy required to raise the temperature of one gram of water one degree Celsius. Determine the calories of energy given off by each substance. Multiply the temperature change by 50 (50 ml of water). A food Calorie is actually 1,000 calories of energy, so you must divide the calories by 1,000 to establish the number of food Calories gained by burning food. Observations: substance starting temperature difference calories temperature after heating Conclusion: Which substance caused the greatest change in the water temperature? Which substance gave off the greatest amount of calories per gram?

15 15 Burn a Peanut, Page 1 Purpose: To determine the calories of heat energy contained in a peanut. Materials: peanut needle test tube ring stand aluminum pan test tube clamp balance scale graduated cylinder thermometer matches clay Procedures: 1. Shape the clay so it makes a support base and place it in the center of the aluminum pan. 2. Use the balance scale to mass the peanut. 3. Measure 10 ml of water into the test tube. 4. Measure the temperature of the water. 5. Stick the peanut onto the dull end of the needle. 6. Stick the needle and peanut into the clay. 7. Bring the ring stand and test tube over the peanut. Adjust the test tube clamp so that the bottom of the test tube is a few centimeters above the peanut. 8. Light the peanut and adjust things so that the flame is hitting the test tube. 9. The peanut should burn for quite awhile. If it goes out, move the ring stand a way and re-light the peanut. Don't let the heat from the match effect the results of the experiment by heating the test tube. 10. When the peanut has finished burning, measure the temperature of the test tube water.

16 16 Burn a Peanut, Page 2 _ Observations: 1. Starting mass of peanut Ending mass of peanut Difference 2. Starting temperature of water Ending temp. Difference 3. A calorie is the amount of energy required to raise the temperature of one gram of water one degree Celsius. Since we used 10 ml of water, you multiply the temperature difference by 10. Calories of energy = 10 x temperature difference Number of calories = 4. Measure the volume of water left in the test tube after heating. It is possible that there is less water present, which means that the peanut boiled away some of the water. It takes 540 calories of heat energy to change one gram of water into a vapor. So if the test tube only contains eight ml of water after the experiment, two grams were changed to a gaseous state. That would be an additional 540 x 2 = 1080 calories. So add this total to the number of calories calculated in observation 3. New total calories = Conclusions: The calories calculated above are not food calories. A food Calorie is equal to 1,000 calories. To indicate a difference between these two units of measurement, the food Calorie is given a capital C. To calculate the food Calories represented by this experiment, we must divide our answer from observations 4 by 1, calories/1,000 = 1.88 Calories from one peanut During digestion, the peanut is broken down chemically in the human body. Glucose, a sugar, is one of the products. This glucose is taken to living cells throughout the body. The sugar is then combined with oxygen collected by the lungs and a reaction occurs. Carbon dioxide, water, and energy are released. Some of the energy is used to warm the body. The carbon dioxide is a waster product, which is carried to the lungs by the circulatory system and exhaled from the body.

17 17 Thermometer Comparison Temperature can be measured with three different scales: Fahrenheit, Celsius, and Kelvin. The Fahrenheit system is used only in the United States and has no scientific application. It was based on the freezing point of a mixture of salt and water. This temperature was assigned zero degrees F. The Celsius scale was based on the freezing and boiling points of water. The freezing point was marked zero and the boiling point of water was marked one hundred. The distance between the two points was divided into one hundred equal parts. The Kelvin scale is based on absolute zero, which is the lowest possible temperature. It is a point where molecular motion stops. The Kelvin scale uses degree marks that are the same size as those used in the Celsius scale. Absolute zero is -273 degrees Celsius. There are no negative numbers in the Kelvin scale, so this point is zero. Also, when giving a temperature reading in Kelvin, there is no degree symbol included. So zero Celsius would be 273 Kelvins or 273 K. The Celsius and Kelvin scales are used for all scientific investigation. Fahrenheit Celsius Kelvin

18 18 Temperature Conversions _ There are three scales used to measure temperature: Celsius, Fahrenheit, and Kelvin. All the countries of the world use the Celsius scale as it is a part of the metric system. The United States uses the Fahrenheit scale and most scientific work is performed with the Kelvin scale, which is called the International System of Units, or SI standard. Use the conversion equations shown in the following tables to convert the temperatures listed at the bottom of the page. To convert Equation Example Fahrenheit to Celsius Celsius to Fahrenheit C = 5/9 x ( F -32) convert 70 F to C C = 5/9 x (70 F - 32) C = 5/9 x 38 = 21.1 C F = (9/5 x C) + 32 convert 30 C to F F = (9/5 x 30 C) + 32 F = = 86 F Celsius to Kelvin K = C convert 30 C to K K = 30 C = 303 K Kelvin to Celsius C = K -273 convert 37 K to C C = 37 K = -236 C Try these: 1. Convert 17 C to Fahrenheit. 2. Convert 100 C to Kelvin. 3. Convert 90 F to Celsius. 4. Convert 120 K to Celsius. 5. Convert 65 F to Kelvin.

19 19 Post-Test A. Directions: Answer the following questions with a short answer. 1. Describe the water cycle and the importance of the sun's radiant energy in that cycle. 2. Bridges have gaps with metal interlocking teeth at key positions. Why? 3. Describe each of the three temperature scales: Fahrenheit, Celsius, and Kelvin. 4. Heat and temperature are not the same thing. How are they different? 5. How does a thermometer work? 6. What is a change of phase, or state? 7. Describe the three forms of heat transfer: conduction, convection, and radiation. 8. What are some of the features of a thermos bottle that make it a good container for keeping cold liquids cold and hot liquids hot?