Distillation Experiment Essay

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Distillation Experiment CHM226 Background The distillation process is a very important technique used to separate compounds based on their boiling points. A substance will boil only when the vapor pressure of the liquid is equal to the external pressure being applied by the surroundings. Distillations can be used to efficiently purify volatile (i.e. low boiling) compounds. The general concept of distillation involves the boiling of a mixture, resulting in the lower boiling compounds boiling off first. This compound is then collected when the vapors are cooled on a condenser. Several different techniques exist for specific applications. The most commonly used method is the simple distillation apparatus (Figure 1). This results in the vapors being collected and affords one solution in moderate purity. It is difficult to separate compounds by this method unless they have a large difference in boiling points (>25 °C), or if ones is trying to removing a liquid from a solid. A similar apparatus is used during a fractional distillation (Figure 2). The primary difference is that a fractionating column provides significantly more surface area, and essentially results in repetitive simple distillations being formed throughout the column. The consecutive evaporations and condensations allow for the separation and purification of compounds with similar boiling points. Boiling points are directly proportional to pressure; therefore as the pressure is decreased the boiling point will also decrease. Compounds with very high boiling points can be distilled much easier if a vacuum is applied. Vacuum distillation is a common technique which allows for the distillation of high boiling compounds under mild conditions. Both the simple and fractional distillation apparatus can be performed under vacuum by attaching the vacuum line to the fume hood vented adapter near the collection

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