Recrystallization is the most common method of purifying nonvolatile organic solids. Recrystallization entails dissolving the material to be purified (the solute) in a suitable hot solvent. As the solvent cools, the solution becomes saturated with the solute, and the solute crystallises out (reforms a solid). Impurities are excluded from the crystal lattice as it develops, completing the purification process. The crystals can then be collected, washed, and dried. The attractive forces that hold solute molecules to other solute molecules (typically Van der Waals interactions) are overcome during the recrystallization process. Recrystallization does not involve the breaking of any chemical bonds.

A successful recrystallization is dependent on the solvent used. When the compound is hot, it must be soluble in the hot solvent but insoluble in the cold solvent. The greater the difference between hot and cold solubility when selecting a solvent, the more product recoverable after recrystallization. The pace of cooling determines the size and quality of the crystals: rapid cooling favours the creation of small crystals, whereas gradual cooling favours the growth of large, generally purer crystals. To be easily removed from the pure crystals, a suitable recrystallization solvent should be somewhat volatile.Aside from that, the solvent should not react with the compound being purified and its boiling point should be lower than the melting point of the compound being purified because solid melts before it dissolves.

The primary precursors of this experiment are benzoic acid and salicylic acid; the acids solute were prepared by a lab assistant at Makmal Gunasama Kimia 3. Makmal Biologi Struktur Dan Fungsi supplied distilled water, which was placed in a tank. Ice was made the day before the experiment by a lab assistant.

Benzoic acid was weighed out at around 1.00g using an analytical balance and transferred to a 125mL conical flask. 20mL of distilled water was measured with a measuring cylinder before being poured to a conical flask. The solution was properly stirred until the acid was dissolved. The solution was then heated on a hot plate until the benzoic acid was completely dissolved; while heating, 3 grains of boiling stones were added to the conical flask. After removing the flask from the hot plate, the solution was left to cool for 5 minutes before being placed in an ice bath for 15 minutes.

The conical flask was taken from the ice bath after 15 minutes. The solution was put into the Büchner funnel, and the filtration process was begun by turning on the vacuum pump. The flask was rinsed with 5mL distilled water before being poured back into the Buchner funnel. The pump was turned on for a few minutes to finish the filtration process. The crystals formed on filter paper. Crystals were let to dry in room temperature air for 15 minutes. By swapping salicylic acid for benzoic acid, all processes were repeated.

Recrystallization is a method used to purify a solid organic material. This method cleans organic compounds of soluble and insoluble contaminants. Because the contaminants are still soluble in cold conditions, the soluble impurities are filtered out of the filtration process based on this experiment. The experiment had unsatisfactory results, with benzoic acid recovering 124.80% and salicylic acid recovering 136.04%.Both outcomes are higher than 100%. One possible reason for the unsatisfactory results is that the filtration process did not vacuum well enough and the crystal did not dry completely.