Purity and Purification of a Liquid

EXPERIMENT #3:

THE PURITY AND PURIFICATION OF LIQUIDS

Created by

Phaedra Malmquist

October 15, 2012

CH 337-Sec 017

ABSTRACT

Lab #3 was carried out in order to separate a mixture of ethyl acetate and toluene using the fractional distillation procedure. Once properly distilled, each fraction was analyzed using gas chromatography (GC) to test the purity of the individual samples.

Distillation is the most common technique used in the separation and purification of a liquid mixture and is done through vaporization and condensation of volatile materials. This method of distillation was effective for this mixture of chemicals due to the fact that the different substances had different boiling points which caused them to vaporize, condense, and separate individually allowing collection into their specific containers.

The fractions that were collected along with three standard samples (one of pure ethyl acetate, one of pure toluene, as well as a 50/50 mixture of the two) were run through the GC apparatus and graphs were produced for each. The peak areas calculated for each graph gave an ideal representation of the composition of the components present in the standards as well as the distilled fractions.

The results gained through the process of fractional distillation can be compared to the findings acquired through gas chromatography (GC), although on a much larger scale than GC. Both processes are intended to separate the components within a mixture and allow for detection of each materials composition; distillation through mL collected of each fraction and GC through the area calculated under each peak. The important information about the GC settings and samples, the peak areas from the GC analysis, and the calculated weight and mole percentages for each distilled fraction were summarized to create Table II.

INTRODUCTION

In fractional distillation, the components of the liquid mixture being separated are soluble within each other prior to boiling and distillation and are separated upon completion by way of the fractioning column. Each component is called a fraction and as the mixture is heated, the vapor that rises condenses on a theoretical plate. The effectiveness of a fractioning column and how the separate theoretical plates within it condense and vaporize different substances in a mixture depends on the chemical properties of each material and the separation in their boiling points. The larger the gap is between each materials boiling point, the better the chance is of achieving the highest amount of purity in each fraction as if