(Solved): Immediately following the recrystallization of aspirin, a student weighed the recovered aspirin, th ...

Immediately following the recrystallization of aspirin, a student weighed the recovered aspirin, then performed melting point and HPLC analysis on the aspirin sample. The sample HPLC results indicated the presence of a single peak, matching the standard \( R_{t} \) of aspirin. The experimental melting point was much lower than expected, and the percent recovery of aspirin was much higher than expected. What is the most likely cause for the percent recovery to be higher than expected? What is the most likely cause for the sample to appear pure based on HPLC analysis, but appear impure based on melting point analysis? Briefly explain your conclusions. 4. The purification of acetaminophen by recrystallization called for the solid to be dissolved in hot water. Once dissolved, a student removed the container of the acetaminophen from the heat source. Rather than allowing the sample to cool to room temperature, the container was placed directly into an ice water bath to induce crystal formation. A large amount of solid formed immediately, however when analyzed by HPLC, the results indicated the presence of two peaks, matching the standard \( R_{t} \) of aspirin and acetaminophen. Propose a cause for the contamination of the acetaminophen sample with aspirin, and how this result could have been avoided. Briefly explain your conclusion.