Crude aspirin is expected to have a larger melting temperature range due to impurities that disrupt the crystal lattice, whereas recrystallized aspirin has fewer impurities and thus a more defined melting point.
One would expect a larger range in temperature for the melting of crude aspirin compared to recrystallized aspirin. Crude aspirin contains impurities that can disrupt the orderly crystal lattice, leading to a broader range of melting temperatures. Impurities can cause melting to start at a lower temperature than pure aspirin because they can create defects in the crystal structure or form eutectic mixtures with a lower melting point. The process of recrystallization aims to remove these impurities, resulting in a more uniform and pure aspirin product. Therefore, the recrystallized aspirin should have a sharper and more defined melting point, showing less variance in temperature from when the crystals start to melt to when they are completely melted.