In the first portion of this experiment, fractional distillation was used to separate two volatile substances from a mixture. To isolated and determine the two liquids that composed the unknown mixture distributed by the Teaching Assistant, I referred to the distinct and known boiling points of the possible solvents. The products separated by fractional distillation were then analyzed using gas chromatography in the second portion of the experiment. This method allowed me to determine the purity of the previously separated liquids on the basis of polarity.
Although simple distillation and fractional distillation are both methods used to isolate pure liquids from a mixture, the technique of fractional distillation is used in this experiment for various reasons. The most obvious difference between these two types of distillation is the length of the columns located between the stillpot and the stillhead. In simple distillation the column is shorter than that used during fractional distillation. The longer fractional distillation column gives the compounds more room, thus allotting them the necessary space and surface area to fully separate. Therefore the method of fractional distillation will yield products with a higher purity than the products of simple distillation.
Another reason fractional distillation was used instead of simple distillation is the factor of time. When dealing with a mixture of two liquids with a difference in boiling points that is less than 40-50O C (such as the liquids in the unknown of this experiment), multiple simple distillations must be done. Each simple distillation will yield a higher concentration of purified liquid with a lower boiling point. Although this method will yield products with the same purity as that of fractional distillation, it is very time consuming. In situations as such, fractional distillation should be used to save time. This method is more efficient for separating liquids with only slight differences in...
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