Jessie Nalley
24 October 2017
Sailajah Gukathasan
Fractional Distillation of Hexane and Toluene
Aim/Purpose: The purpose of this experiment is to separate and purify the liquid components of a mixture with a known composition using a technique called fractional distillation. In order to do so, a liquid mixture is separated into three fractions in the first distillation; then, one of the fractions produced is redistilled to increase the purity of the liquid. Since two rounds of distillation occur, the process is termed fractional distillation. Additionally, it is crucial for students to understand the principles of gas chromatography so the purity and percent composition of each fraction can be determined.
Theory: The basis for this
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Theoretical plates represent the stage in which two phases, such as the liquid and vapor phase of a substance, establish equilibrium with one another. Thus, since the Hickman still has a short column and a complete separation of hexane and toluene cannot be achieved in one cycle, there are two theoretical plates in this experiment: one from the original distillation where three fractions are recovered, and one from the redistillation of one of the fractions to produce more pure portions. This experiment involves the separation of a solution containing hexane and toluene.
These compounds meet the criteria mentioned above since their boiling points are approximately 40°C apart (hexane: 69°C; toluene: 111°C). During the first distillation, the liquid mixture is separated into three fractions. These three fractions must be collected at the specific temperature ranges shown below:
Desired Composition
Temperature Range
Mostly Hexane
60°-70°C
Equal Portions of Hexane and Toluene
75°-85°C
Mostly Toluene
85°-105°C
The phase diagram of hexane and toluene depicts the relationship between temperature and the mole fraction of the mixture, revealing that as the mole fraction of hexane and toluene changes, the boiling point of the mixture changes as well. It is important to note that at any given point, the mole fraction of hexane and toluene must equal 1.0. The graph below displays the changes mentioned above in regards to the phase diagram and the
Objective: The main goal of this lab is to learn how separation of binary liquid mixtures is performed. Especially when the two liquids have boiling points varying by about 30° C. Hexane can be separated from toluene in this experiment because of the difference in their boiling points. Since toluene has a higher boiling point, it will left at the bottom while the hexane starts to boil out and collect in the Hickman still. GC measurements help us in determining how accurate our data is by making a graph of the amount of hexane and toluene in each fraction. Also this lab gives experience with semi-micro
Fractional distillation uses a column filled with glass beads that improve the separation between the liquids that are being distilled. [6] The glass beads allow the refluxing liquid to condense, re-evaporate, and then condense again. [6] Fractional distillation is better used for separating mixtures of liquids that have close boiling point separations.[6] Due to the boiling point of 1-methylcyclohexene being 110°C, 3-methylcyclohexene being 104°C, and methylenecyclohexane being 102-103°C, fractional distillation was used instead of simple distillation. Even though the boiling points are different, they are still collected together, making them azeotropes. Due to this, they cannot be separated by fractional
Distillation of the first product began at 83 °C. A Pasteur pipette was used to remove 1-ml of the distillate into a vial. A second vial was filled with distillate until it reached 1-ml. As the second vial is being filled, observe the temperature and remove the apparatus from the heat source if there is an observed drop in temperature.
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Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.
1.) Briefly explain the concept of steam distillation. What is the difference between a simple distillation and a steam distillation? When a mixture of two immiscible liquids are distilled it is referred to as codistillation. This process is referred to as steam distillation when one of the liquids is water. This distillation is used to separate organic liquids from natural products and reaction mixtures in which the final product results in high boiling residues such as tars, inorganic salts, and other relatively involatile components. It is useful in isolating volatile oils from various parts of plants and not useful in the final purification of a
In this experiment, distillations were done. This is a technique that utilizes the differing boiling points of two or more compounds in a mixture in order to separate the compounds from the mixture. The way fractional distillation works is that the initial mixture is boiled up to the point of the lower boiling point compound; this compound then evaporates. This compound is then
Whereas for simple distillation, the compounds need to be around 80C apart in order for proper separation to occur. Thus, cyclohexane and toluene were not able to be properly separated since the boiling point for cyclohexane was 80.74C while the boiling point of toluene was 110.6C—there two boiling points are fairly close to one another. Thus, the mole fraction for cyclohexane and toluene were fairly low when compared to cyclohexane and
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The main objective of the distillation lab was to identify the composition of an unknown binary solution. The only known component is that the boiling point of the two components were at least 40˚C apart in boiling points. Due to the difference in boiling points, fractional distillation would be an easy way to determine the identity of each component of the binary solution. In the experiment, 30mL of the unknown binary solution was ran through the fractional distillation apparatus. As the solution boiled, gas from the unknown solution ran through the column, which had a temperature gradient to allow rapid and repeated distillations, and one of the components were isolated. By recording the temperature and amount of