Recrystallization Lab Report

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I. Abstract The experiment was about using a method of recrystallization to reform benzoic acid and unknown compound, and identifying that compound. The main principle is the polarity and solubility of compound. The compound was dissolved completely with distilled water in hot temperature and reformed back in cold environment. After the experiment, there were up to more than 50% of the compound being recrystallized and the unknown compound had the melting point at 165.2oC. The experiment showed the connection of polarity and solubility of the compound in order to recrystallize.
II. Introduction A solid’s purification, when recrystallized with a solvent, is depending on the solubility of it in a given solvent. When the sample contains
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Then we added 20 mL of DW to the flask and put it into a water bath. We used the stirring rod to stir the mixture up for completely dissolved. If the sample did not dissolve, we put more DW drop by drop using the dropper. When the sample was fully dissolved, we gently put the flask into an ice bath and wait until it recrystallized. We noticed not to move the sample around or it would break the crystals inside. After that, we filtrated the solution to get the crystals out. Using a funnel and filter paper, we poured the sample into the funnel, the crystal would be remain in the filter paper. Finally, we let the crystals dry and weighted it in order to determine the percent of …show more content…
An ideal recrystallization solvent should have these properties: - The compound is soluble in hot temperature and insoluble in cold temperature. The difference in at hot and cold temperature is very important to the process. Because when the solvent is insoluble in hot temperature, it will not dissolve result in cannot be recrystallized. - There are two phases to identify the unwanted impurities: dissolved form present in solvent at normal temperature or undissolved form in higher temperature. Therefore, the impurities will be taken out using the hot filtration when dissolving the impure solids. After the cooling process, the impurities will again be separated out by another filtration. - Do not let the solvent react with the substance, or resulting in loosing amount of desired compound during recrystallize process. - The solvent should have enough volatility in order for removing the sample after crystallization. It helps the drying process of the compound become easier and faster. [1] Why are crystals washed with additional solvent when collected? Why cold

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