What data will be used to compare the crude product versus the recrystallized product?

The comparison of the crude product and the recrystallized product is most effectively done using melting points. Melting point determination is a critical technique in organic chemistry that helps in assessing the purity and identity of solid compounds. When a compound is crystallized, impurities often are excluded from the crystal lattice, leading to a more defined melting point range. Pure substances typically have sharp melting points, whereas impurities can cause a depression and broadening of the melting point range.

Therefore, by determining the melting points of both the crude and recrystallized products, one can infer the effectiveness of the recrystallization process. A higher and sharper melting point observed in the recrystallized product compared to the crude product indicates successful purification. This method directly relates to the physical properties of the compounds, making it a key factor in evaluating their quality after recrystallization.

While mass measurements, IR spectra, and NMR spectra can provide useful information about yields and chemical structures, they do not directly assess the purity of crystalline solids in the same way melting point analysis does.