Distillation – Lab Report

By: Victoria Anatsui

Introduction:

The purpose of this lab is to learn the important separation methods of distillation/fractional distillation. These methods separate miscible liquids by utilizing their differences in boiling point. Simple distillation is great for separating liquids with very large differences in boiling points while fractional distillation is better at separating liquids with closer boiling points.

Procedure:

We set up both a simple and fractional distillation apparatus with 60ml of a methanol/water mixture (Unknown Bottle C) in a 100ml round bottom flask. We applied heat with a heating mantle to both flasks and watched the mixture come to a boil. Then we lowered the heat. Two people took data on the temperature and the amount of distillate collected. They measured this using a 10ml-graduated cylinder, which they emptied when it was full. We collected distillate until we had successive temperature readings around boiling point of water (100 degrees Celsius).

Observations/Results:

The simple distillation was very slow. There was no large jump in temperature difference during the distillation. The simple distillation also seemed to have been distilling water at the end of the distillation even though the temperature wouldn’t go above 98 degrees Celsius. The fractional distillation did have a large jump in temperature once we had collected about 5 mL of distillate.  The large jump is appropriate because it represents the point where we begin to distill water because there wasn’t much methanol left in the boiling solution. We did collect some water as part of out distillation because we let the distillation continue until we hit the boiling point of water. The fractional distillation was more accurate because it allowed the condensation and vaporization of the liquid many times in the fractioning column, which provides a more pure distillate.