3. Start the Logger Pro program on your computer. Open the file “04 Freezing Point” from the Advanced Chemistry with Vernier folder. Part I Determine the Freezing Temperature of Pure Lauric Acid 4. Heat 350 mL of tap water in a 400 mL beaker on a hot plate. (Use a setting of 6 on the hot plate.) While the water is heating, move on to the next step. 5. Weigh ~8 g. of lauric acid. Record the exact mass, and add it to the test tube provided. 6. Add about 300 mL of room temperature tap water to a 400 mL beaker. Place the beaker on the base of the ring stand. 7. Secure the test tube containing lauric acid with a utility clamp attached to the rod on the hot plate, similar to the diagram above. Lower the test tube into the hot water bath. Place the temperature probe inside the test tube so that the tip of the probe rests at the bottom of the tube. While the lauric acid is melting, go on to the next step. 8. When the lauric acid has reached approximately 60-65 °C, use the utility clamp to transfer the test tube containing the hot, molten lauric acid from the hot plate to the ring stand. Fasten the utility clamp to the ring stand so that the test tube is above the water bath. Click to begin the data collection. Lower the test tube into the water bath. Make sure the water level outside the test tube is higher than the lauric acid level inside the test tube, as shown in Figure 1. CAUTION: Be careful not to spill the hot lauric acid on yourself, and do not touch the bottom of the test tube. Perform this step quickly. 9. With a very slight up-and-down motion of the Temperature Probe, continuously stir the lauric acid for the ten-minute duration of the experiment. 10. When the data collection is complete, use the hot water bath to melt the lauric acid enough to safely remove the Temperature Probe. Carefully wipe any excess lauric acid liquid from the probe with a paper towel or tissue.
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