Melting Point Lab Report

Introduction: The melting point of a pure substance is a characteristic that is physically consistent with each specific substance. When a substance is impure, it causes the melting point to decrease and the range of the melting point to increase. In order to identify a pure substance, it must be purified in order to get an accurate melting point estimation. Purification can be done through crystallization. Crystallization is one of the simplest and most effecting ways to purify a solid. The procedure involves dissolving the impure solid, gravity filtering the hot solution through fluted filter paper to remove impurities and then cooling the filtrate to effect recovery of the material as a solid and then filtered again by suction filtration.

o Unknown sample (18) is yellow in color o First time attempting to dissolve, the solution looked like it fully dissolved but once it began to cool, it began to crystallize again boiled again o After adding the charcoal, solution started to turn a mint green color and after heating again the solution became very clear and light green color o Accidently got charcoal in flask when it was being filtered so we filtered it twice o 1st filtration had too much water, crystals did not form when placing flask in ice bath
Discussion and Results:
When determining the melting point of Benzoic Acid, we observed that the solid began melting at a temperature of 122.6 ºC. Due to this temperature reading we came the conclusion that apparatus #4 has a calibration error of approximately ±0.2 ºC. This error could be due to small impurity of the solid as well as technical malfunctions with the

During the gravity filtration, a small amount of charcoal accidently passed through the filter and therefore contaminating our filtered solution. Because of this mistake we needed to repeat the gravity filtration in order to extract the charcoal from the solution. As a result of repeating the filtration and adding an excess amount of water to the solution, when placing our solution in an ice bath, our mixture was unable to crystalize. Because we needed the crystals to form in order to perform the vacuum filtration, we needed to perform the entire crystallization and purification of the experiment once more. After doing so, we observed the crystals form and were able to proceed and perform the vacuum filtration. When weighing our final mass of the solid, we recorded the weight to be 2.20 g which lead to the percent recovery of