METHODS AND MANIPULATION 25 Distillation. If the impurities in a liquid are non-volatile, the liquid may be purified by direct distillation, the impurities remaining in the distilling-flask. This process is therefore essentially the same as a simple distillation for boiling-point determination, and has been already described on pp. 7-9. If, however, the impurities are themselves volatile liquids, then the separation of these impurities from the main bulk of the required substance is achieved by fractional distillation. If an ordinary distilling-flask, such as that shown in Fig. 2, p. 8, is used for this purpose, however, only a very partial separation of the liquid components of the crude mixture is usually obtained, unless there is a considerable difference in boiling-point between the impurities and the main component. To obtain a much sharper and more complete separation, a fractionating column is em-ployed. Fractional Distillation. For this type of distillation, the
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.