What Is The Melting Point Of P-Acetamidophenol

951 Words4 Pages
Sarah Min CHEM 143A: Section A03 A10627548 April 14, 2015 Lab Report 1 - Recrystallization and Identification of Unknown Introduction The main concept in this experiment is recrystallization. Recrystallization is the process where the solute (a crystalline material) is dissolved in a hot solvent. The heated solution is filtered (generally via vacuum or gravity filtration) and is returned back to its solid crystalline state when the solution cools down. Recrystallization is best for isolating and purifying solids. A key part of recrystallization is the solubility of the solid. A basic fact is solid dissolves in a liquid. This comes from dipolar interactions, hydrogen bonding as well interactions like London Forces. While solubility of a solid…show more content…
When the melting point was determined, the unknown melted around the range of the melting point of p-Acetamidophenol’s (169-172°C). When the unknown was mixed with Salicylic acid (157-159°C), the melting point dramatically decreased and the range became greater, which follows the trend of mixed melting points. Conversely, when the unknown was mixed with p-Acetamidophenol, the mixed melting point was in the range for p-Acetamidophenol. These findings gave evidence that the unknown is p-Acetamidophenol. My % recovery results for macroscale and microscale recrystallization are where results vary. For macroscale, I had a % recovery of 46.34% and a 13.33% recovery for microscale. Microscale recrystallization has a higher percent recovery because the Craig tube is used for both filtration and vacuuming. This allows for volumes to be recrystallized at a higher accuracy. An ideal % recovery is at least the 80% mark and both of my macroscale and microscale were not close to…show more content…
The obvious one is human error. Basic things such as losing product while transferring to different containers can result in a low % recovery. However, it is not only human error that can cause a low % recovery. Impurities can also influence % recovery. When crystallization occurs, molecules will arrange themselves on the same compound (a similar concept to “Like dissolves like”). However with impurities inside of the solution that became saturated in the solvent, these too also begin to crystallize. As a result, not as many crystals will crystallize due to the possible impurities. In my results, I stated that I saw black specks at the bottom of my test tube. I suspect that these black specks could be impurities and may have resulted in a lower % recovery. I believe the biggest reason why my macroscsale and microscale recrystallizations are low is due to the filtrations. In macroscale, a hot gravity filtration via a Hirsh funnel with cotton and a vacuum filtration is conducted. For microscsale, a hot gravity filtration is done to the unknown. It is extremely key for the cotton or the filter paper in these filtrations to be hot. Once the solution begins to cool, recrystallization automatically begins. Because of this, the solution must always be hot as well as the filter or else premature crystals may form. There may have been crystals left in the filtrate or stuck to the sides of the test tube that were not filtered properly due to premature

    More about What Is The Melting Point Of P-Acetamidophenol

      Open Document