Lab Report 5

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Northeastern University *

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2312

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Chemistry

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Feb 20, 2024

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Uploaded by AgentCrownHummingbird43

Experiment #5 Distillation and Boiling Point Teaching Assistant - Date Performed - November 2, 2023 Date Due – November 9, 2023

Experimental Objective This experiment aimed to identify the better way by distilling a solvent mixture using two distinct approaches. This innovative method was carried out by heating equal parts of cyclohexane and toluene in two separate apparatuses—one for fractional distillation and the other for simple distillation. A thermometer and a syringe were used to monitor the distillation process. Plotting the generated points on a graph allowed for comparison in order to identify whether approach was better. Procedure The two processes employed in this experiment were nearly identical, with the two instruments being the main difference. The hot plate with the sand bath was switched on to preheat before starting either of the two distillations. From there, a 10 ml round-bottom flask with a boiling chip inside was filled with 4.0 mL of cyclohexane and 4.0 mL of toluene. The round-bottom flask was attached to a Hickman distillation head via a Claisen adaptor for the straightforward distillation. Lastly, a drying tube and thermometer adaptor were attached to the side arm of the Claisen adaptor. The apparatus for the fractional distillation was assembled similarly to that of the simple distillation, but between the round-bottom flask and the Hickman distillation head was a reflux condenser with a copper wire inside. After being put into each device, the thermometer was submerged in the hot sand bath. A syringe was used to remove the distillate, which developed in the Hickman head as the solution heated. Until roughly 1 mL remained in the simple distillation apparatus or 6 mL was collected in the fractional distillation device, these steps were repeated. Every time, records were made of the temperature and the volume of distillate. The entire volume removed was plotted on the x-axis of the graph, and the temperature at each extraction was put on the y-axis. These graphics were used to compare the two approaches.

Result Table 1: Recorded Data During Simple and Fractional Distillation Simple Distillation Fractional Distillation Amount Withdrawn (mL) Total Withdrawn (mL) Temperature (°C) Amount Withdrawn (mL) Total Withdrawn (mL) Temperature (°C) 0.1 0.1 55 0.2 0.2 62 0.1 0.2 60 0.25 0.45 76 0.1 0.3 62 0.22 0.67 81 0.1 0.4 62 0.2 0.87 84 0.1 0.5 66 0.55 1.42 85 0.1 0.6 68 0.5 1.92 86 0.1 0.7 69 0.35 2.27 86 0.3 1 72 0.35 2.62 87 0.2 1.2 74 0.25 2.87 87 0.1 1.3 75 0.22 3.09 87 0.2 1.5 75 0.37 3.46 90 There was a large deviation in protocol due to a small mistake performed at the beginning of the experiment with fractional distillation. Too much copper wire was put in the reflux condenser, making the reaction inefficient and hindering the natural progression of the experiment. This was only discovered towards the end, at which point the reflux condenser and copper wire were replaced. It is difficult to predict how this affected the data. It’s also likely the sand heated too quickly so there was a narrower range of data.

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Despite this, two distinct graphs that matched the theoretical graphs covered in the characterization below were produced (Figures 1 and 2). A phase shift was the only modification that was seen; there were no color changes or other changes. There was also some condensation on the glass's side because of the phase shift. The properties of each method were used to forecast the theoretical graphs for each approach. A somewhat linear graph or a progressive curve should be displayed by the simple distillation. This is a result of the mixture's constituents, toluene and cyclohexane, having comparable boiling points. Since the liquids are going through a phase change, two plateaus should appear for the fractional distillation. No phase shift is suggested by the increasing temperature between the plateaus. Fractional distillation works well for displaying the mixture's constituents' various boiling points. The theoretical graphs and the graphs made with the experimental points agreed upon. As expected for a simple distillation, the graph of the distillation (Figure 1) displayed a slightly curved or linear trend. The graph displayed a tiny curve since the boiling temperatures of cyclohexane and toluene varied by 30ºC. There were two discernible but not quite separate plateaus on the fractional distillation graph (Figure 2). The plateaus resulted from the addition of a reflux condenser to the device, which expanded the area on which the gas could condense. This made it possible for the component with the higher boiling point to condense more quickly and shielded the gas from contaminants. Given that the two components were able to be collected at two distinct points, as indicated by the two plateaus, there has been some separation process occurring. According to the experiment, fractional distillation is a superior approach than simple distillation since it can demonstrate the differences in boiling points rather than the simultaneous boiling of the mixture. The two distinct boiling points can be seen with the help of the plateaus. Conclusion The purpose of this experiment was to compare two ways for distilling a combination of cyclohexane and toluene and identify which approach was better. Plotting the discovered points in this experiment demonstrated the clear distinctions between the two approaches. Simple distillations displayed a slight curve, indicating that they work better in tests with larger boiling point variations than in this one. Fractional distillations effectively illustrate the difference between the two components with comparable boiling points by displaying two distinct plateaus.