Lab 5 Acid/Base Extractions Essay

The purpose of this experiment is to separate either the organic base (amine) or organic acid (carboxylic acid) from a mixture that contains inorganic impurities (salt) by performing a liquid-liquid extraction and then taking a melting point. Key Experimental Details and Observations Our starting material, Compound B, was a fine white powder and weighed 0.535g. The final product was a shiny white sheet that resembled acrylic paint and weighed 0.109g. Results Our percent yield was 0.109g/0.535g x 100 = 20.4%. Discussion and Conclusions The melting point ranges we got for compound B ranged from 110.8-114.0 Â °C, while the melting point range for benzoic acid is 121.0-123.0Â °C and 103.0-107.0Â °C for 4-amino acetophenone. Since the ranges we acquired for compound B are directly in between both acid and base melting points, we can conclude that the purity for compound B is relatively high due to the compound being made up of equal parts of benzoic acid and 4-amino acetophenone. Thus saying that our melting point ranges are fairly accurate because they exemplify an equal percentage of both compounds, which is exactly what compound B is made up of. The purity can also be concluded through the melting points depression because depression arises from impurities within the lattice of a crystalized sample. We acquired a percent yield of 20.4%, which is relatively low. This result could be from part of the compound B solution being left behind in the Erlenmeyer flask when pouring the solution into the vacuum filtrate. The efficiency of a liquid-liquid extraction is high because it did allow us to gain some of our starting product back. We were able to isolate the acid from the base by deprotonating the solution with 10mL of NaOH. This caused the benzoic acid to settle at the bottom of the separatory flask because the NaOH broke it into ions, which made the acid polar. We then protonated the solution by adding HCl, which cause the acid to separate from the solution.