To Purify a Liquid Through the Process of Distillation, Reflux, and Evaporation

Experiment 6

Distillation, Reflux, and Evaporation

Daniella Portelada

CH 203 (52)

October 26, 2011

Experimental Objective:

The objective of this experiment was to purify a liquid through the process of distillation, reflux, and evaporation.

Procedure:

Part 1: Distilling a cyclohexane/toluene mixture

A mixture of 4.0 mL of cyclohexane and 3.0 mL of toluene was obtained and then put in a 25 mL round bottom flask with a boiling chip. The Hickman still was then attached to the flask and assembled in the sand bath on a hot plate. The heat was slowly turned on and when vapors started to appear and recondense small aliquots of the sample were removed from the collar of the still and the temperature was recorded each time. The average aliquot was about 0.5 mL. Aliquots continued to be removed in this way until there was nearly nothing left in the flask so it was taken off the heat to cool. All of the aliquots were saved in individual vials. The last thing done for this portion of the experiment was taking the refractive index and boiling point of samples 2.5-3.0 mL and the residue.

Part 2: Fractional Distillation Technique

35 mL of unknown A was obtained and put in a 50 mL round bottom flask with boiling chips. A fractioning column was then attached to the flask and a condenser was attached to the fractioning column with a graduated cylinder at the end to catch the drippings. The fractioning column was insulated by wrapping paper towels around it and securing it with a clamp. After attaching all the proper hoses the water was gently turned on and the flask was heated. The first few drops of the distillate was discarded and then every 0.5 mL the temperature and volume was recorded until the temperature dropped and once again began to rise. Af the temperature began to rise again one last recording was made and then the flask was taken off the heat to cool and the device was carefully taken apart.

Results:

Part 1:

Approx.

Vol.Range

of fraction Actual

Volume

of aliquot Cumulative

Volume

of fractions Temperature

at end of

fraction **nD

of

fraction *v/v %

composition

of fraction **miniscale

Test tube

Bp

mL mL mL oC (unitless) % toluene oC

1st drop xx ~0 75o xx xx xx

0.0-0.5 0.50 0.50 80o 1.4483 78o

0.5-1.0 0.50 1.00 84o 1.4439 79o

1.0-1.5 0.50 1.50 84.5o 1.4447 30o

1.5-2.0 0.55 2.05 85o 1.440 97o

2.0-2.5 0.50 2.55 86o 1.447 80o

*2.5-3.0 0.50 3.05 87.5o 1.455 80o

3.0-3.5 0.50 3.55 87.5o 1.446 85o

3.5-4.0 0.50 4.05 85o 1.4362 91o

4.0-4.5 0.40 4.45 84o 1.4496 83o