CHEM 6AL Experiment #1: Solubility and Melting Point Introduction In this experiment, the solubility of organic compounds in various solvents and the melting point of organic compounds were experimentally tested. This experiment was conducted to familiarize the experimenters with basic techniques used in the organic chemistry laboratory, as well as to cement an understanding of the effect intermolecular forces have on the physical properties of organic compounds. More specifically, the interplay between non-polar carbon-chain elements of organic compounds and polar functional groups on the compounds were tested. Both polar and non-polar solvents were used in combination with these compounds. Discussion In the first part of this experiment, the solubility of Benzophenone, malonic acid, and biphenyl were tested for solubility in water, methanol, and hexane. Benzophenone was predicted to be soluble in water, partially soluble in methanol, and insoluble in hexane, but was found to be insoluble in water and hexane, and soluble in methanol. Its insolubility in hexane was likely an error. Malonic acid, being extremely polar, was predicted to be soluble in water and methanol, and insoluble in hexane, which was confirmed experimentally. Biphenyl was predicted to be insoluble in all three solvents, and the experiment confirmed these except for methanol, in which is was soluble. The results for hexane and methanol are likely erroneous. In the second part of the experiment, the solubility of three alcohols (1-octanol, 1-butanol, and methanol) were tested in water and hexane. The results 1-octanol and methanol lined up with the predictions, with the former being insoluble in water and soluble in hexane, and the latter being soluble in water and insoluble in hexane. 1-butanol was predicted to be partially soluble in both solvents, but was found to be insoluble in water and soluble in hexane. In the third part of the experiment, the miscibility of various compounds were tested together in five trials. Water and ethanol, as well as hexane and methylene chloride were predicted to be miscible (respectively), and these predictions were confirmed experimentally. However, water and diethyl ether, as well as water and methylene chloride were predicted to be miscible, but were found to be immiscible. Water and hexane, being very polar and very non-polar (respectively), were predicted to be immiscible and confirmed experimentally. In the fourth part of the experiment, the solubility of benzoic acid and ethyl-4-aminobenzoate was tested in water, 1.0M NaOH, and 1.0M HCl. Benzoic acid was predicted to be insoluble in HCL, soluble in NaOH, and partially soluble in water. These findings were confirmed, except for a partial solubility in hydrochloric acid, which was likely erroneous. Ethyl-4-aminobenzoate was predicted to be insoluble in NaOH and soluble in HCl, and these predictions were confirmed, but was found to be insoluble in water contrary to the prediction of partial solubility. When 6.0M HCL was added to the solution of benzoic acid and NaOH, the benzoic acid re-precipitated due to its re-protonation. When 6.0M NaOH was added to the solution of ethyl-4-aminobenzoate and HCl, the same occurred. In general, the results obtained during the first four parts of the experiment (barring a couple likely erroneous results) are consistent with the notion that “like dissolves like.” In more technical terms, solutes with polar functional groups were found to be more soluble in polar solvents, while solutes with significant non-polar chains were found to be more soluble in non-https://www.coursehero.com/file/18159141/CHEM-6AL-Experiment-1-Lab-Report/This study resource wasshared via CourseHero.compolar organic solvents. Erroneous predictions were due to an incorrect understanding of the polarity of the compounds. In the fifth part of the experiment, the melting point of pure cinnamic acid and pure urea, as well as 75%-25% mixtures of each (by mass) were tested. The literature values for the melting point of cinnamic acid and urea are 133°C, and were found to be within the range of 134-138°C and 131-137°C, respectively. The mixture of 75% cinnamic acid was measured at 98-118°C, while that of 75% urea was measured at 94-109°C. The results of the melting point portion of the experiment are consistent with the literature and theory, which predict that the mixtures have lower melting points due to the disruption in the regularly ordered form of a pure compound. Conclusion In general, this experiment was successful in its goals, in that it cemented an understanding of the way polarity and intermolecular forces affect solubility. Erroneous predictions arose from erroneous understandings of the polarity of the compounds used, and to this end the experiment assisted in rectifying these misunderstanding. Additionally, being able to recognize which results are likely erroneous further cemented the understanding of these forces’ effect. Generally, the errors were far and few between considering that the compounds being used in the laboratory are quite impure, and the equipment being difficult to sterilize. Other sources contributing to the errors could have arisen from contamination due to imperfect laboratory techniques. More specifically, the sterilization of measuring tools that were reused throughout the experiment was likely insufficient to eliminate the presence of other compounds. https://www.coursehero.com/file/18159141/CHEM-6AL-Experiment-1-Lab-Report/This study resource wasshared via CourseHero.comPowered by TCPDF