In this experiment of preparation and recrystallization of aspirin, me and my lab partner got a justifiable percentage yield of aspirin crystals but a rather pure sample of the crystals as our melting point range of 132.5?-133.2? is very close to the pure aspirin crystals of 138?-140?. The reasons for such unfavourable yield may be the excessive amount of solvent (ethanol) used in the process of dissolving the salicylic acid. As the process of dissolving was slow and ineffectual we decided to add, with the consent of our practical lecturer, approximately 2 ml more ethanol to the solution. This caused the solution to be excessively saturated with ethanol causing the aspirin crystals to stay suspended in the solution instead of crystallizing and also filtered away during suction filtration as it is still in the solution. We could have avoided this by bringing the overall temperature of the solution to be higher as this will cause the speed of the reaction to be faster. Another reason of our low yield percentage may be due to cooling rate and cooling time as the aspirin in the solution may not have crystallized. The cooling rate also affects the yield slightly as the faster it cools the smaller the crystals will be, this causes some of the crystals to be washed down the sides of filter paper when pouring the solution on the funnel due to its minute size. This could have been avoided by cooling the solution at a slower rate and allowing the solution to cool for a longer period of time. Now moving on to the factors that affected our purity of the aspirin crystal. One factor that affected our purity may be that impurities like left over solvents and unreacted reactants that may have bonded with the aspirin crystals. This could have been eluded by washing the aspirin crystal more with cold deionised water during the suction filtration process. Also, to address the safety precautions we carried out during the experiment are that safety goggles and latex gloves are worn at all times when conducting the experiments with chemicals as to prevent the chemicals from contacting our eyes or skin as these chemicals are strong irritants and very corrosive. Cotton gloves are also worn when handling glass ware that we need to put or take out from the oven as it may cause thermal hazards like burns and blisters.