The weight of the purified caffeine is often much lower than the weight of the crude caffeine. Explain why the percent recovery is frequently low?

see explanation

Explanation:

When caffeine is purified, the impurities are removed,  these impurities are responsible for the greater mass of pure caffeine compared to the mass of the pure sample.

The percent recovery of caffeine is frequently low because some caffeine is often left behind in the solvent during the process of recrystallization.

Secondly, since caffeine is a sublime substance, some caffeine may be lost o sublimation leading to a low percent recovery of pure caffeine.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.