Computer2Computer 2Freezing and Melting of WaterFreezing and Melting of WaterFreezing temperature, the temperature at which a substance turns from liquid to solid, and melting temperature, the temperature at which a substance turns from a solid to a liquid, are characteristic physical properties. In this experiment, the cooling and warming behavior of a familiar substance, water, will be investigated. By examining graphs of the data, the freezing and melting temperatures of water will be determined and compared.OBJECTIVESIn this experiment, you willCollect temperature data during the freezing and melting of water.Analyze graphs to determine the freezing and melting temperatures of water.Determine the relationship between the freezing and melting temperatures of water.Figure 1MATERIALS
400 mL beaker
Vernier computer interface
10 mL graduated cylinder
Part I: Freezing
1. Fill a 400 mL beaker 1/3 full with ice, then add 100 mL of water.
2. Put 5 mL of water into a test tube and use a utility clamp to fasten the test tube to a ring stand. The test tube should be clamped above the water bath. Place a Temperature Probe into the water inside the test tube.
3. Connect the probe to the computer interface. Prepare the computer for data collection by opening the file "02 Freeze Melt Water" from the Chemistry with Vernier folder of Logger Pro.
4. When everything is ready, click to begin data collection. Then lower the test tube into the ice-water bath.
5. Soon after lowering the test tube, add 5 spoons of salt to the beaker and stir with a stirring rod. Continue to stir the ice-water bath during Part I. Important: Stir enough to dissolve the salt.
6. Slightly, but continuously, move the probe during the first 10 minutes of Part I. Be careful to keep the probe in, and not above, the ice as it forms. When 10 minutes have gone by, stop moving the probe and allow it to freeze into the ice. Add more ice cubes to the beaker as the original ice cubes get smaller.
7. When 15 minutes have passed, data collection will stop. Keep the test tube submerged in the ice-water bath until Step 10.
8. On the displayed graph, analyze the flat part of the curve to determine the freezing temperature of water:
Move the mouse pointer to the beginning of the graph's flat part. Press the mouse button and hold it down as you drag across the flat part to select it.
Click on the Statistics button, . The mean temperature value for the selected data is listed in the statistics box on the graph. Record this value as the freezing temperature in your data table.
To remove the statistics box, click on the upper-left corner of the box.
Part II: Melting
9. Prepare the computer for data collection. From the Experiment menu, choose Store Latest...