Lab Report Fractional Distillation

Fractional distillation was performed in this lab to separate a mixture of two miscible liquids with a difference in boiling points of less than 40 C, and to predict their identities. After that, gas chromatography was used to confirm the identities of the two liquids in the unknown solution, and to obtain the ratio of the composition of the solution with respect to these two liquids.

Distillation is a separation technique that relies on two substances having different boiling points, so that one evaporates and condenses in a separate flask. Simple distillation can be used for mixtures of solids and liquids, as liquids typically have lower boiling points than solids, or for mixtures of two liquids with a difference in boiling points greater

Fractional distillation produces the same result as a series of simple distillations, which yield a more pure product after each consecutive distillation. In fractional distillation, a second condenser is added between the round bottom flask and the second condenser, and is used as a fractionating column in order to create a temperature gradient. The temperature is highest at the bottom of the column, where it is in contact with the round bottom flask, and lowest at the top of the column. As the vapors rise through the column, the vapors for the liquid with higher boiling condense as the temperature drops, and fall back into the boiling flask. The vapors from the liquid with the lower boiling point pass into the second condenser, and are condensed and collected in a flask or other vessel. After all the vapors of the first liquid are collected, the temperature on the boiling plate can be increased so the liquid with the higher boiling point passes through the column, and is collected in a separate vessel. The fractionating column can be packed with glass beads or other such materials to increase surface area for condensation, although that was not done in this experiment. The unknown solution was separated into three falcon tubes. Tube A contained mostly the lower boiling point liquid, B contains both liquids, and C contained mostly the higher boiling point