CHEM 1102 Experiment 3 Lauren Cheever 2/12/18 Dr. Booth Page 1 of 3 Using Freezing-Point Depression to Find Molecular Weight Abstracts: The purpose of this experiment was too find the molecular weight of benzoic acid using freezing point depression. The experimental Using Freezing-Point Depression to Find Molecular Weight molecular weight of benzoic acid was 11.2 g/mol. The freezing temperature of pure lauric acid was 43.7 degrees Celsius, and for the benzoic acid, lauric acid mixture it was 39.0 degrees Celsius. The experimental weight of benzoic acid was calculated by dividing the mass of benzoic acid by the number of moles in benzoic acid; that came out too 11.2 g/mol. By dividing the freezing point of lauric acid by the Kf of lauric acid (3.9), the molality was achieved. The molality was 11.21m. The percent discrepancy between the experimental and accepted values was calculated by subtracting the molecular weight of benzoic acid from the molality, then dividing that by the molality, and finally multiplying that by 100. The percent discrepancy came out to 989%. Introduction: In this experiment, the freezing temperature of the pure solvent, lauric acid, is found first. After that, the freezing point of a lauric acid, benzoic acid mixture with a mass of 9 grams is found. The freezing temperatures of these two were found by placing the test tubes, one at a time, into a 400 mL beaker of 300mL hot water, and allowing it to melt. Next the test tube should be taken out of the hot water and placed in room temperature water.
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- Spring '14
- Mole, Freezing-point depression, Lauric acid, Lauren Cheever