In this laboratory we will experience the technique of distillation. Distillation is useful for the purification of liquid mixtures when the boiling points of the components of the mixture are distinct and low enough to allow distillation without degradation. If the lower boiling component of a mixture is not valuable (i.e. it can be discarded afterwards) and the higher boiling component has a boiling point different by at least 20°C, then simple distillation may be used to purify the higher boiling component. If the liquids have very similar boiling points or if the low boiling material is of value, then fractional distillation is employed. Other techniques are also available but are outside the scope of this laboratory exercise.
acetone
1-butanol
2-butanol
isobutanol (2-methyl-1-propanol)
tert-butyl alcohol (2-methyl-2-propanol)
ethyl acetate
Working with a partner, set up a simple distillation of the mixture. Once the first drop of distillate is collected note the temperature and continue to do so with each 0.5 mL collected. Also record the time for each of these data entries. You should set the temperature to distill at a rate between 10-20 drops per minute. Faster than that will give very poor results. After collecting a total of 30 mL distillate, allow the apparatus to cool and proceed as directed by your laboratory instructor. Based on the data that you obtained, can you hypothesize the identity of the two liquids in the mixture? Comment in your lab notebook.
Use the computer to graph the temperature (on the y-axis) vs. the mL collected (x-axis) for both the simple and fractional distillation (on the same graph). Mark the graph to show the location at which each of the fractions was collected.
Literature Sources:
Safety and Risk Phrases
ChemExper for bp/safety/risk
Fisher Scientific, bp/MSDS
Aldrich Chemical Company, bp/MSDS
Acros Chemicals, bp/MSDS
NIST Chemistry Webbook for bp
SIRI MSDS Index
MSDS, Oxford University
TOXNET Hazardous Substances Database