Lab 5 Liquids and Solids

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Liquids and Solids Purpose: The goal of this experiment is to be able to identify melting/boiling points of substances. We can then use these methods to identify unknown substances because of constants in melting/boiling points. Procedure: 1. Boiling Point a. Begin by adding 1 mL of rubbing alcohol to test tube and attach a thermometer to it. b. Place assembly in water bath and begin to heat beaker c. As isopropyl alcohol begins to boil, bubbles begin flowing from the capillary tube d. While temperature is decreasing, record the temp. when the last air bubble comes out of the capillary tube. e. Let assembly cool down and repeat process two more times. 2. Melting Point a. Place powdered acetamide crystals into capillary tube and attach to thermometer. b. Once again, place assembly in water bath and begin to heat c. When acetamide has begun to melt, record the temperature. d. Let assembly cool down and record temperature when acetamide begins to recrystallize. e. Repeat process two more times. Data: Data Table 1 | | | Rubbing Alcohol Trial # | Boiling Point | Percent Error | 1 | 79.5 C | 3.52% | 2 | 84.0 C | 1.90% | 3 | 83.5 C | 1.30% | Data Table 2 | | | | Acetamide Trial # | Melting Point | Freezing Point | Percent Error (Melting Point) | 1 | 79.5 C | 57.5 C | 3.50% | 2 | 80.5 C | 59.5 C | 0.60% | 3 | 78.0 C | 61.0 C | 3.70% | Observations: It was observed that thermometer placement could affect the readings in the water bath. I ended up holding the test tube assembly to where the bottom of the test tube was not touching the bottom of the beaker to ensure better readings. Also, when substances recrystallize, I am not sure whether to take a reading when the substance has full crystallized or begun to so results could be fairly inaccurate. Questions: A. Why is it useful

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