Lab 1 Report - Simple vs. Fractional Distillation Results and Discussion PDF

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Simple vs. Fractional Distillation Results and Discussion...

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Elizabeth Valcourt CHEM 546.02 Simple vs. Fractional Distillation 19 September 2017

Introduction: Distillation is a laboratory method used to purify liquids. A mixture is heated to the point of vaporization, then condensed down and collected. The liquid collected is called the distillate. Because substances have different boiling points, they evaporate at different times. With simple distillation, the desired substance’s boiling point must be vastly different than any other substance in the mixture. The substance with the lower boiling point will vaporize faster than the other substance(s), allowing it to be collected first. The vaporized substance will rise through the distillation head and condense as it moves down the condenser and into the collecting container. Fractional distillation is a better choice when the substances have boiling points that are closer together. In this method, a fractionating column is added to the apparatus. The vapor moves through this tube before it reaches the distillation head. It is filled with steel wool or glass beads to increase surface area. This causes the vapor to condense and re-vaporize many times before it reaches the top of the column, making the overall boiling point reading more accurate than simple distillation.1

References: 1. Hill, Richard; Barbaro, John. Experiments in Organic Chemistry. 3rd ed.; Contemporary Publishing Company of Raleigh, Inc.: Raleigh, NC, 2005.

Results and Discussion: 1. The line of the simple distillation increased more smoothly than the fractional distillation line. The fractional distillation had a drastic increase from the volume of 15mL to 16mL. This tells us that the first liquid had all evaporated and the remaining liquid had to heat up more to reach its boiling point. 2. The fractional distillation technique did a better job at separating MeOH and water because there was a distinct jump in the graph. This means the liquid in the apparatus had to heat up further. The simple distillation did not have a clear break in the graph, making analysis of the boiling point impossible. 3. The system was collecting MeOH until it reached the break at 15-16mL. The system switched to collect water where the graph has the steepest slope, which is at approximately 15.5mL. This means there was 15.5mL of MeOH in the original solution, which was 29mL. Dividing 15.5mL by 29mL gives the percent composition of MeOH in the solution, which equates to be 53%....