Fractional Distillation Lab Report Discussion

The process of distillation is commonly used to purify liquids. The process of distillation allows separation of distillates based on the temperatures at which they boil. Liquids with higher volatility boil at lower rates than liquids that are less volatile. Because of this when a mixture of two substances is created there will be a spike in the boiling point. At the spike the more volatile substance has vaporized and condense out of the mixture leaving the less volatile liquid. Thus the temperature has to increase or spike to boil the remaining substance. In the case of toluene and cyclohexane, cyclohexane is more volatile and has a lower boiling point. Simple distillation only evaporates and condenses a liquid once where in fractional
Unlike in the simple distillation there is a spike in the data between trial 15 and trial 16. Toluenes boiling point is 110 degrees where cyclohexanes boiling point is 80.74 degrees. The fractional distillation process more closely represents the relationship between these two boiling points.

Graph 1: Boiling points of Simple and Fractional Distillation of Toluene and Cyclohexane

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The samples collected during fractional distillation were used in gas chromatography to test the purity of the distillate. When examining the vials one was missing and two had erased labels. Based on the reading from the mystery vials and the relation to the other vials the trial they could've come from was approximated. Based on the overall data there was very little change in the purity of the mixture.

Table 3: Gas Chromatography Results from Fractional Distillate

Vial trial nd20

1 1.4364

2 1.4389

3 1.4408

4 Lost vial

5 Lost vial

6 1.4564

7 1.4757

8 1.4885

9 1.4935