Distillation CHE311L - Dr. Kyte PDF

Preview

Summary

Dr. Kyte...

Description

The Purification of Ethanol by Distillation

CHE311L 10/06/16

Summary: This experiment was carried out to separate pure ethanol and water from a mixture using both simple and fractional distillation. The percent recovery of ethanol was also calculated along with obtaining the refractive index and comparing it to the literature value to determine the purity of the ethanol.

Introduction: Distillation is one of the methods used to purify liquids with different boiling points. The liquid with the lower boiling point will evaporate out first leaving the liquid with the higher boiling point, and thus separating both liquids. There are 2 types of distillation methods. Simple distillation heats a liquid to its boiling point and is used to separate only 2 liquids. The liquid is heated to evaporation and the vapor enters the condenser where it is changed back into liquid. Fractional distillation separates two or more liquids with boiling points that are not too far from each other. The separation factor is a fractioning column, which contains glass beads. A refractive index can tell the ID of a liquid and its purity. The purer the liquid, the closer it will be to the literature value. In this experiment, both methods of distillation will take place for the same liquid mixture.

Methods: A. Simple distillation of an ethanol/water mixture 50 mL of impure ethanol was obtained and weighed. Simple distillation apparatus was set up and ethanol mixture slowly came to a boil. Distillate was collected in a 10mL graduated cylinder and temperature recorded for each mL obtained. Mass of ethanol obtained was determined and percent recovery calculated along with the refractive index. B. Fractional distillation of an ethanol/water mixture Part A was repeated except using fractional distillation instead of simple. C. Analysis of the distillation Graph of volume of liquid vs the temp @ which it was obtained was plotted.

Results:

Data Tables

Table 1. Volume of pure Ethanol vs Temp Volume ml 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Temp.  C 68.5 71.0 71.0 71.5 72.5 72.5 76.0 78.0 78.8 79.0 79.0 79.5 79.5 79.5 79.8 79.8

Calculations: Mass of beaker: 68.023 g Mass of beaker + Ethanol: 82.274g Mass of pure ethanol: 14.251g

Percentage recovery = (mass of ethanol obtained/ mass of impure ethanol) * 100% = 14.251/26.292g * 100 = 54.20 %

Refractive index: 1.3635

Discussion: The refractive index obtained (1.3635) vs the literature value (1.3612) are not too far in comparison, suggesting that the ethanol was relatively pure.

Conclusion: 16 mL of pure ethanol was obtained, with a refractive index of 1.3615 and a percent recovery of 54.20 %.

References: [ CITATION Org \l 1033 ]...