Hexane And Toluene Experiment

1366 Words 6 Pages
Purpose
The purpose of this experiment was to collect three different fractions of a mixture of hexane and toluene at differing temperatures. From there, the fractions would be measured via gas chromatography to discover the percent composition of hexane and toluene in each fraction with the ultimate goal of having one fraction with mostly hexane, one with mostly toluene, and one with an even mixture of the two. Along with this, there is also the goal of redistilling one of the fractions in order to further reduce impurities by leaving the fraction with only one of the two molecular compounds.
Theory
Boiling point and vapor pressure are related to one another in an inverse relationship—meaning that as boiling point increases, the vapor pressure
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The first fraction results in a fairly accurate percent composition of hexane and toluene. The second fraction, on the other hand, is supposed to be an even mixture (50%/50%) of hexane and toluene. Instead, the results are similar in nature to what was found in fraction one. Both of these fractions had approximately 60% hexane and 30% toluene. Fraction 3 is consistent with the expected results of having a much greater percent composition of toluene than hexane. The redistillation of fraction 3 was successful, although not entirely so. It is expected that a second redistillation should result in a mixture of pure toluene—however, the amount of hexane was only slightly decreased. Because the original percent composition of toluene was originally high at 92.7%, it makes sense that it would be difficult to make much of a difference in the percent …show more content…
After carrying out the first part of the experiment, students were instructed to evaluate their own results using gas chromatography. Gas chromatography results in the percent composition of each liquid within a mixture and thus provides students with an accurate way to assess their work. Finally, students were ultimately meant to purify either toluene or hexane from a mixture of the two by redistilling one of the previously collected fractions. This is an efficient way to teach students the best methods for separating and purifying mixtures made up of compounds with very different boiling

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