Thirdly, the impurities and acetanilide crystals must be separated. Therefore, the solution must be cooled, thus the solubility of the compound will decrease, and the compound will precipitate. Indeed, the solution must be cooled slowly – from room temperature then to an ice bath –, as a drastic decrease in temperature would cause the compound to precipitate too fast, thus impurities to be trapped within the crystals structure. Therefore, the compound will precipitate and be separated from the impurities, which will remain dissolved in the solution.
