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Desk #Chemistry 36 Section 102September 26, 2005TA: Experiment: Distillation and Boiling PointFinal ReportI. IntroductionDistillation is an important technique in organic chemistry used to separate a mixture of liquids or purify a liquid via boiling. Heating a liquid to boiling allows the substance to change into its gas phase and leave the mixture. When the mixture being distilled contains two substances of differing boiling points, the substance with the lower boiling point will convert to its gas phase more rapidly than the other. Condensing this vapor will result in an isolated and purified substance with the lower boiling point.Depending on the difference in boiling points of the two liquids in a mixture, chemists use two distillation techniques. Simple distillation is used for samples with a difference in boiling point of at least 75°C. The mixture is heated to boiling and the vapor is isolated and condensed. Since the boiling points are so far apart, the vapors are primarily of the lower boilingpoint substance and no further separation is required. For substances with closer boiling points, fractional distillation must be used to help separate the vapors by several evaporations and condensations before isolation. The fractional distillation column serves as a place for this isolation to occur. In this experiment, each lab desk in a row did a different procedure. The four were simple and fractional distillation of a toluene/cyclohexane mixture as well as simple and fractional distillation of a ethanol/water mixture. Each student was to do one of these proceduresand record the temperature of the vapor versus milliliters of distillate and share data with the rest of the row. The goal was to show the differences in separation of simple and fractional
II. Procedure and Data/ObservationsAs stated previously, the first procedure was broken into four sections. The simple distillation apparatus was assembled by placing a 100 mL flask in a heated sand bath. Into this flask was put a 1” stir bar to prevent bumping and either a mixture of cyclohexane and toluene orethanol and water. A three-way connecting tube connected flask to the West Condenser and thermometer; all this was supported by ring stands and clamps. The thermometer was positionedjust under the side arm of the of the three-way connecting tube to prevent inaccurate recording ofvapor temperature. Moreover, the thermometer’s accuracy was tested by recording the temperature of boiling distilled water and comparing to the listed value of 100°C. The West