Simple and Fractional Distillation
The purpose of this experiment was to separate two liquids using Simple and Fractional Distillations. Separation by distillation works by manipulating the chemicals’ colligative properties and intermolecular forces.
Reagents in the Experiment:
This experiment attempted to separate two liquids, cyclohexane and toluene. These chemicals have different intermolecular forces and therefore have dissimilar boiling points. Distillation is an excellent way to isolate two compounds if their boiling points are sufficiently far apart.
In the simple distillation, heat was applied to a flask containing the two solvents. The flask was connected to the distillation apparatus. The solvents’ vapor slowly escaped the flask, contacted the thermometer, and wisped into the condensing chamber. The condensing chamber is continuously cooled by water, thereby forcing the solvent vapor to liquefy. The distilled solvents were collected. It was expected that the solvents’ evaporate with different rates, particularly that, cyclohexane with a lower boiling point, would have a greater concentration in the distillate beaker than toluene. A graph of temperature on volume is shown below for the simple distillation. The results show that the distillate contains a volume of toluene and cyclohexane; separation was not successful.
Fractional distillation differs from simple distillation because it includes a ‘fractioning column’. The column towers above the heated flask and was stuffed with a metal sponge, allowing for numerous liquid/vapor equilibrium phases of the distillate across the sponge’s surface. As the fractional distillation graph above indicates, this method was highly successful in separating the two liquid chemicals. Unlike the scattered data in the simple distillation plot, there was a defined temperature at which cyclohexane vaporized (~72° C) and another when toluene vaporized (~90° C). Fractional distillation was better suited for this separation than simple distillation.