Crystallization Lab

Melting points are indicative of identifying an unknown product and the level of impurity the product contains. In this case, the possible identity of the product based on its melting points are determined by comparing the obtained melting points of the product to the melting points of the five possible products. Two mini capillaries, containing the product only, were used to determine the product’s melting point. For one mini capillary, the temperature range was 132.1-134.2℃, and the product’s melting point for the second minicapillary ranged from 135.1-137.5℃. In addition, melting points were obtained with the product mixed with meso-hydrobenzoin. The temperature range was 135.0-136.0℃ and 135.0-137.5℃. Although the recorded melting point values fall into the racemic range, but the results still indicate that the product is a meso-hydrobenzoin. The melting point values for the product mixed with the meso-hydrobenzoin standard explains that it is unlikely that the product is racemic. The melting point values were two degrees from each other due to the meso-hydrobenzoin standard making

Once there was enough compound in the tube, the tube was turned over and the bottom of the tube was tapped on a table to move the collected material to the bottom of a tube. Once the compound was in the tube it was labeled and the process was repeated until all the tubes were filled with their respective compound. The labeled tubes were placed on the lab bench as the Mel Temp was being set up. In order to get a more precise measurement on the Mel Temp apparatus, a standard was used that had a similar melting temperature to pure Urea and pure trans-cinnamic acid. In this lab the standard was succinimide having a melting point of 124˚C-125˚C, making it close to the melting point of Pure urea (132˚C-133˚C) and trans-cinnamic acid (132˚C-134˚C). Next, the Mel Temp apparatus was plugged in and set to a starting temperature. When the apparatus was ready, the ready light turned on and a tube was placed into the Mel Temp and monitored. The starting melting temperature and final melting temperature was then recorded in degrees Celsius. After the final temperature for the sample was recorded, the tube was taken out of the apparatus and placed on the lab bench. This process was repeated using the three other ratios of Urea and trans-cinnamic acid and the two pure

Next, 1mL plus an additional 10 drops of 10% sodium carbonate was added drop-wise to the beaker until the solution reached a pH of 8. The precipitate formed (crude benzocaine product) was collected via vacuum filtration and washed with water during the transfer into the Hirsch funnel. The product was allowed to dry for one week after which the mass and melting point of the crystals were measured.

In the introduction of the experiment it stated that, “Chemists can only obtain a melting range of a 2 - 3°C accuracy. This is usually sufficient for most uses of the melting point.” This statement assures that the melting point results obtained from this experiment are good results. Part 1 and 2 results were a little higher than the supposed melting range, but knowing that only a 2-3°C accuracy can only be obtained these are good

The vial was removed from the heat and cooled to room temperature. The spin vane was rinsed with 2-3 drops of warm water over the conical vial. The vial was cooled to room temperature then placed in an ice bath for 15 minutes. The liquid was decanted from the mixture and the resulting crystals were dried on filter paper. The crystals were then placed on a watch glass for further drying. The crystals were weighed and a small sample was placed into a capillary tube for melting point determination.

The product was then suspended in 2 ml of water with a stir rod in a 50 ml Erlenmeyer flask and heated to boiling. Water was added in one milliliter increments until all the product was dissolved (18 ml added total). The saturated solution was allowed to slowly cool, and gradual white crystal formation was observed. Recrystallized product was collected once more by suction filtration with the Hirsch funnel once crystallization ceased. Collected product dried on a watch glass for a week, weighed 0.14 g (1.2 mmol), and the melting point was 139°-141°

21) After all of the solid dissolves, move the flask from the hot plate and allow it cool to room temperature. After a while, crystals should appear in the flask.

Tube 4 now should only have crude solid in the tube and it is then weighed. The tube is placed into a 50℃ water bath and then approximately 0.5 -1 ml of methanol is added, as well as H2O until the solution gets cloudy, once the solution is dissolved it is cooled to room temperature and then iced. The crystals are then collected using a Hirsh funnel. Next a small amount (~ 0.1g) of the crystals are placed into a melting point tube and placed into the melting point machine to record the unknown neutral substances melting point.

Attach your paperclip to your beaker, and lower your seed crystal into your solution (See Figure

Although the amount recovered was high, the crystals still had a yellow color, showing that impurities remained in the sample. However, the melting point was within the range of the acid identified. Conclusion: The experiment determined that the unknown sample was phthalic acid due to the melting point of 208.9 degrees Celsius. The correction of the machine was found to be 0.3 degrees Celsius, and it was machine #5.

After crystals appeared in the mixture, the mixture was vacuum-filtered and washed with cold water. Since the crystals were still very wet after being vacuum-filtered with a Buchner funnel, they were pressed between several filter papers to dry thoroughly (1.888 g, 10 mmol, 48%) mp:

A compound can be identified by its physical properties like melting point, boiling point, and density. The melting point can show how pure a compound is. The purer the compound, the higher the melting point and the narrower it’s melting point range. Adding continuous amounts of impurity to a pure compound will cause the melting point to decrease. In this experiment the melting point of crystalline substances are observed to see how pure the compound is. This was done by putting the compounds into a capillary tube. The capillary tube is then inserted into a melting point apparatus and heated. The temperature at which the compound begins to liquefy and when the compound becomes completely liquefied will show how pure the substance is. The melting

We left the solution to sit ther for two weeks, and then after two weeks, we added 1 μl of Izit dye to the drops, then waited two weeks for the crystals to absorb the dye in-order to observe the crystal under the microscope. Results for Row A with NaCl being the changing variable. The concentration of PEG for all of the wells was 20%. Well A1: Crystals produced in 1 M NaCl Well A2: Crystals produced 1.2M NaCl Well A3: Crystals produced 1.4 M NaCl

Recrystallization was done to remove impurities from the sample. The percent recovery of benzoic acid during recrystallization is 23.02%. The difference between the pure and impure samples was observed by comparison of melting points. It was found that impure sample had a lower and wider melting point range of 120.1-122.2 (C). The pure sample melting point range was 121.3-122.5 (C). These ranges helped determine purity by comparing the known melting point of pure benzoic acid.

Once the range is obtained, remove the thermometer and beaker. Pour out the hot water and allow both the thermometer and the beaker to cool. Once cool, repeat the previous steps with the second compound, tetradecanol. At the conclusion of the second experiment, repeat the steps for a third and final time using an equal mixture of both compounds. Be sure to record the melting point range for all three experiments.