The technique used in this experiment is recrystallization. Recrystallization is an often-used method for purifying solids. Recrystallization works by taking advantage of the different solubility properties of compounds, and allows impurities to be removed from crude solids.
Performing a recrystallization is usually a straightforward task. First, you add a small amount of solvent to the impure compound in a flask, and heat the contents until all the material has dissolved. Then, you cool the solution, allowing crystals of purified solid to crash out of solution, while undesirable impurities stay dissolved in the solvent. You then isolate the pure crystals by vacuum filtration, and discard the waste solution. Performing a recrystallization...
Nowadays, aspirin is often given to patients immediately after a heart attack to prevent recurrence or cardiac tissue death.
Aspirin is a non-steroidal anti-inflammatory drug (NSAID). NSAIDs are medications with analgesic, antipyretic (something that reduces a fever), and in higher doses anti-inflammatory effects. Non-steroidal means they are not steroids, which often have similar effects. As analgesics, NSAIDs are generally non-narcotic (do not cause insensibility or stupor). The most prominent NSAIDs are aspirin, ibuprofen and naproxen - mainly because most of them are OTC (over-the-counter, no prescription required) medications. Aspirin was the first discovered NSAID. 
Aspirin among all these usefulness, do has its side effect such as upset stomach, heartburn, drowsiness, and headache. 
The equipment used in this experiment are, Conical flask, Acetic anhydride, Salicylic acid, Concentrated sulfuric acid, Water bath, Distilled water , Cold water, Hot water, Filter paper, Ethanol, Hot plate and Dry watch glass....
Increasing the temperature will not speed up the reaction as expected. Thus, a catalyst was needed as salicylic acid is stabilized by its benzene ring, with lone pairs from the carbonyl group and the hydroxyl group delocalizing with the electrons of the aromatic ring. In this case, we utilized sulfuric acid (H₂SO₄) as the reaction catalyst to speed up the reaction.
While the reaction proceeded, the color of the reaction mixture changed from white to colorless. This was due to the increased heat, which increased solubility and allowed the white salicylic acid crystals to dissolve, forming a colorless mixture. Also, acetylsalicylic acid is much more soluble in water than salicylic acid, though both exist as white crystals. Thus, the disappearance of the color white in the reaction also meant that more soluble acetylsalicylic acid crystals which could dissolve were being formed, and that relatively insoluble salicylic acid...
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