Separation Of Benzoic Acid Lab Report

In this lab, extraction was used as a method for separating a mixture of compounds. Specifically, Benzocaine and Benzoic Acid were individually isolated from a starting mixture which consisted of both components. During this lab, Benzocaine was isolated into crystals, while benzoic acid formed a white powdery solid. This was done by first isolating benzocaine. Once separated, this clear liquid had 6M of sodium hydroxide added to it and was put in an ice bath. Once cooled, crystals formed. These crystals were the pure benzocaine, and therefore filtered out of the liquid. Similar steps were taken to recover the benzoic acid. This white powdery substance was isolated from the white solid layer in the first step, or bottom layer. The white solution underwent base extraction.

An amount of 15mL of 6M hydrochloric acid was added to the solution and then was put in an ice bath. Crystals again formed, and were again filtered out of the liquid. These crystals made up the benzoic acid present in the original mixture. These crystals, once dried, were extremely white and had a more powdery consistency then benzocaine. Also during this lab, a percent recovery was found for both pure substances. The percent recovery found for benzocaine was 1%, while the percent recovery of benzoic acid was 35%. This was done by taking the final mass of the benzocaine, .02g, and dividing it by the mass of the beginning mixture, 2.0g, then multiplying by 100. The percent recovery for benzoic acid was found the same way, but the final mass for benzoic acid was 0.70g. These low percentages are a result of errors during the experiment. One source of error was during the first separation of layers. When separating the two layers, some of the top aqueous layer flowed out with the bottom layer. This caused slight impunity in the compounds. In the first separation step, the escape of the clear top layer resulted in less benzoic