Investigating Changes in Temperature Problem: What happens to the temperature of a substance during a phase change? Background: In paragraph form, explain what you know about phase changes. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Hypothesis: Write a hypothesis that relates to the problem. Make sure it is in (if-then form) ________________________________________________________________________ ________________________________________________________________________ Materials: 500 mL beaker Clock with second hand Crushed Ice Thermometer Glass stirring rod Hot plate Graph paper Procedure: 1. On a sheet of notebook paper, make a data table with two columns. One column labeled time in minutes and one column temperature of water in ˚C. 2. Set up the hot plate as shown by your instructor. 3. Fill the 500 mL beaker to the 250 mL level (about 1/2 full) of ice. Caution: Use care when handling glassware to avoid breakage. Wipe up any spilled ice immediately to avoid slips and falls. 4. Place the beaker the hot plate. Insert a thermometer into the ice, wait about 20 seconds for the thermometer to adjust to the ice. Record the temperature reading next to the 0 minutes entry in the data table. 5. Turn on the hot plate. Slowly stir the ice with the stirring rod. 6. Observe and record the temperature at one-minute intervals until all the ice has changed to a liquid. Circle this temperature and also the temperature when the ice started to melt. 7. Continue taking readings until the water starts to boil. 8. Circle the temperature when the water began to boil. 9. Make five measurements after the water has started to boil 10. Turn off the burner. 11. Ask your instructor to discard the hot water. 12. On a separate sheet of graph paper, graph your data. Conclusion: write a conclusion that relates the hypothesis to the data. Make sure you use some of the following vocabulary. Solid, liquid, gas, molecules, kinetic energy, endothermic, melting point, boiling point, heat of vaporization, heat of fusion. Think of these questions when writing the conclusion 1. What happened to the temperature of the water during the phase changes? 2. What happened to the energy that was transferred from the Bunsen burner to the ice or water during the phase changes? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ____________________________________________(attach another sheet if necessary)
