crystals_sample_report

crystals_sample_report - This sample report is of an...

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Unformatted text preview: This sample report is of an experiment we will be completing later in the semester. It is only partially completed but the basic elements and format for a formal report are given. This sample report, as well as other sample reports are available for download from the home page for this course. Elli Font ALWAYS CHECK YOUR GRAMMAR & style CHEM 231 January 1, 2002 Solubility and Recrystallization of Organic Substances PURPOSE please always double spaced In this experiment the solubility of four organic compounds were determined in subtitles three different solvents ranging in polarity. The best solvent for re-crystallization of each compound was determined through their solubility characteristics. Finally, the techniques for re-crystallization were practiced on samples of pure and impure acetanilide. After the re-crystallization of the impure sample the percentage yield and purity produced noted and evaluated, and the FTIR, HNMR, and CNMR spectra were analyzed and discussed. CONCLUSION note the general purpose has been restated Begin each conclusioin by briefly restating your purpose. In this experiment, the solubility of acetanilide, naphthalene, benzoic acid, and resorcinol in cold and hot solvents of water, petroleum ether, and 95% ethanol were measured. The compounds and solvents both ranged in polarity. Finally, the technique of recrystallization from the minimum amount of boiling solvent for both pure and impure samples of acetanilide was practiced. ALWAYS write in third person past tense passive voice. Before determining which is a better solvent, one should know a good solvent is. A good solvent has certain characteristics that pertain to the solute-solvent mixture as being: ♦ LIST the characteristics of a good solvent which is most important? and why? By looking at the physical structures and determining whether the molecule is polar or non-polar it can be determined which solvents will be best at dissolving the particular molecule as each compound has different solubility in different solvents governed by the general rule like dissolves like. In Part A, the best solvent for re-crystallization of each compound was to be determined through their solubility characteristics, see Table I. Table 1: Results for Part A Compounds Resorcinol Naphthalene Benzoic Acid Acetanilide O Structure OH Mp _____oC2 Cold H20 Soluble Hot H20 Bp: 100 oC results upon cooling the solution _____oC1 _____oC3 _____oC3 NA NA Cold Ethanol Hot Ethanol Bp: ______1 results upon cooling the solution Click here to download the table templates Cold Pet. Ether Hot Pet. Ether Bp: ______1 results upon cooling the solution 1. Literature source (reference it) [you may or may not have more than one literature source. 2. Literature source (reference it) 3. Literature source (reference it) Recrytallization solvent recommendation How did structure affect solubility? What if any was the relationship between structure and solubility?; did your predicted results match the experimental results These results in Table I were consistent with expect results. Resorcinol showed …. ....structurally resorcinol has polar OH bonds capable of hydrogen bonding with water.... Naphthalene showed …. Benzoic acid showed …. Acetanilide showed …. In Part B, a 1.00 gram sample of pure acetanilide acid recrystallized from the minimum amount of boiling water. The mixture was cooled in an ice bath, crystals formed, and, the solution was vacuum filtered to yield ______ grams of pure acetanilide as a white crystalline; see notebook pages _____ to _____. Several recrystallization trials were conducted and results summarized below. Table 2: Recrystallization of Pure Acetanilide, Part B Initial Mass of acetanilide (g) Mass of crystal in Crop 1 (g) Mass of crystal in Crop 2 (g) Total Mass recovered (g) Percent Yield Trial One %yield 1.00 0.38 38% 0.54 54% 0.92 92% 92% (combined yield) Overall Average Yield 91% Normalization factor Trial Two %yield 1.00 0.78 78% 0.12 12% 0.90 90% 90% (combined yield) click here to download template 0.91 Recrystallization of pure acetanilide from the minimum amount of boiling water in three trials of showed…. First and second crops were recovered …. This showed…. complete these sentences In Part C, an impure acetanilide was issued as a (give physical properties) mixture. A 1.00 gram sample of brown impure acetanilide acid was dissolved in boiling water in the presence of activate charcoal to decolorize, gravity filtered, and recyrstallized from the Always check\grammar minimum amount of boiling water. Upon cyrstallization after the mixture was cooled for ten minutes in an ice, the solution was vacuum filtered to yield ______ grams of pure acetanilide as a white crystalline with a m.p. _______(Lit1_______), see notebook pages _____ to _____. A normalized yield was calculated….. Table 3: Recrystallization of Impure Acetanilide, Part C Initial Mass of acetanilide (g) Mass of crystal in Crop 1 (g) Mass of crystal in Crop 2 (g) Total Mass recovered (g) Melting Point Crop 1 Melting Point Crop 2 Percent Yield Normalized Yield based on Part B results, 0.91 normalization factor Average Normalized Yield Trial One %yield 1.000 0.53 53% 0.12 12% 0.65 65% 112-114 oC 100-109 oC 53% (uncombined yield) 58% (uncombined yield) Trial Two %yield 1.000 0.38 38% 0.17 17% 0.55 55% 114-115 oC 111-115 oC 55% (combined yield) 61% (combined yield) 59.5% The results of three trials showed ….Based on the average normalized yield… In comparison between the yields of recrystallized pure and impure samples…. These results were in agreement with expected results as seen in the case of ….. In the purification both gravity and vacuum filtration were used. The difference between each technique was… Where appropriate discuss the difference in percentage yields of the first and second crops. After recrystallization of impure acetanilide in part C, FTIR spectroscopy showed WORD PROCESS LIKE WE DID FOR THE FTIR UNK. Include a SCANNED copy of the spectrum with my initials written on it. How did your spectrum compare to that of the actual spectrum. Be sure you downloaded the actual spectrum as thin film (KBr) NOT Nujol. 1 HNMR spectroscopy showed…. WORD PROCESS LIKE WE DID FOR THE NMR UNK give a brief discussion of prominent features observed in the actual spectrum 13 CNMR spectroscopy showed…. WORD PROCESS LIKE WE DID FOR THE NMR UNK brief discussion of prominent in the features observed in the actual spectrum DON'T forget to include at the end of each report the following: E.Final Four Questions. After your conclusion, please provide answers to the following four questions: 1) What did I do in this activity, 2) What did I see in this activity, 3) What did I learn in this activity, and 4) What would like to do next. ...
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