Thin Layer Chromatography

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The objective of this lab was to find a recrystallization solvent and to purify impure benzoic acid by recrystallization.
To begin the experiment, a comparative Thin Layer Chromatography (TLC) was conducted with impure benzoic acid and pure benzoic acid. After removing the TLC plate from the TLC chamber a baseline was drawn and a UV light was used to view the spots and circles were drawn. Then, the TLC plate was stained in Iodine to see impurities. Impurities were seen in impure benzoic acid and the mixture of impure and pure benzoic acid. Also, the melting point range (107.5-122.0 °C) of impure benzoic acid was found. Before recrystallization began, the recrystallization solvent was first determined. First, four test tubes were placed in
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Next, 50 mL of water was added into the flask. A boiling stick was placed in the flask, then the flask was heated in a sand bath. After boiling started the impure benzoic acid started to dissolve and was removed from the sand bath. The flask cooled down at room temperature for a few minutes. An ice bath was prepared in small container, then a beaker filled with water was added in ice bath. As the flask cooled down crystals started to form and after the flask cooled it was added in the ice bath. The crystal was collected in a vacuum filtration. For the vacuum filtration, a filter flask was clamped so the apparatus did not fall over. A filter paper was added to the funnel and wet completely with water. The vacuum was added to the vacuum hose and turned on. Then the crystals were poured onto the filter paper. The flask was rinsed with water to remove all the crystals. After 20-30 seconds, the vacuum was removed and turned off. The funnel was removed and the filter paper scraped off. The crystals were then dried by pressing it in between two filter papers. The dried crystals, was used to conduct TLC. After removing the TLC plate from the chamber, a baseline was drawn and UV light was used to view the spots and a circle was drawn. The TLC plate was stained in Iodine to see if there were any impurities and no impurities were seen on the plate. The melting point range

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