Aspirin is synthesized from salicylic acid using acetic anhydride as a reactant. Salicylic acid is reacted with excess acetic anhydride in the presence of phosphoric acid as a catalyst. Water is then added which causes aspirin to precipitate out of solution. The crude aspirin product is analyzed using melting point determination, titration, and UV-Vis spectroscopy. The purity and percent yield of the aspirin product are calculated from these analytical methods.