Lab Report: Separation and Purification of Organic Compounds: Crystallization

My hypothesis is that if I add different amounts of sugar to the same amount of boiling water and allow it to be cooled, than the one with the additional cup of sugar will be the one that grows more crystals. I determined that my hypothesis was correct. The glass I chose to add the pure cane sugar did grow much more crystals at a

During recrystallization, the solution was to be cooled to room temperature before placing it in an ice bath. Doing this allows enough time for the crystals to be formed because as the temperature decreases, the rate of crystallization slows down. If the solution was placed in the ice bath too quickly, then the cold would have blocked out the impurities and trapped them in the solution. The more impurities present, the lower the melting point so data would have been inaccurate. Also, if the melting point apparatus wasn’t set up correctly, the data would have been imprecise.

The mixture was transferred to an ice bath to crystallize the product, after which the product was collected by vacuum filtration on a Hirsch funnel, washing the flask with small aliquots of cold xylene and pouring the solution over the crystals, allowing the vacuum to thoroughly dry the product. Additional drying was achieved by transferring the product to filter paper and pressing the crystals to remove any excess moisture. The product was then weighed and a melting point determined. A comparative TLC was run in Hexanes:Ethyl Acetate solvent against maleic anhydride to verify the purity of the

Recrystallization is a technique frequently used in organic chemistry to purify solid organic compounds. The goal of this technique is to allow organic compounds to form crystal lattice structures, and to remove any of the impurities that do not align within this crystal structure.1 The theory behind recrystallization revolves around entropy; as heat will cause a organic compound to dissolve (increase in entropy), a decrease in heat will then allow that organic compound to reform (decrease in entropy) and become purer.2

The product was placed in a Craig tube and several drops of hot (100°C) solvent (50% water, 50% methanol, by volume) was added and heated until all of the crystals dissolved. The Craig tube was plugged and set in an Erlenmeyer flask to cool. Crystallization was induced once the mixture was at room temperature by scratching the inner wall of the tube. It was then placed into an ice bath for ten minutes until crystallization was complete. The tube was then

The first step is the separation of the solid crystals back into separate ions, a positive ammonium ion and a negative nitrate ion. The break these ionic bonds requires a lot of energy which means heat must be taken from the surrounding water. The second step the water molecules, which are H2O, are attracted to the ions and attach themselves to the ions. The second step actually causes heat to be produced to the surrounding liquid mixture. .Even

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.

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°

Method: Distillation is based on the fact that the matter can exist in three phases - - solid, liquid and gas. As the temperature of a pure substance is increased, it passes through these phases, making a transition at a specific temperature from solid to liquid (melting point--mp) and then at a higher temperature from liquid to gas (boiling point--bp). Distillation involves evaporating a liquid into a gas phase, then condensing the gas back into a liquid and collecting the liquid in a clean receiver. Substances that have a higher boiling point than the desired material will not distill at the

In performing the proper experimentation, we poured some of the methylene blue substrate in a piece of paper, for ease transport towards the agar plates. We performed it cautiously by not inhaling it, for it is a form of powder. We carefully place the substrate at the center of the agar plates, to ensure that is that there is enough space for diffusion to take place. After the moment we placed the substrate, we carefully placed a transparent ruler under the plate to measure the diameter of the substrate in 0 minutes. We carefully note the time, having a 15-minute interval and record the changes in the diameter of the substrate. We continued it, until we have an hour observation.

In this experiment, separation of fluorene and 9-fluorenone took place using column chromatography. The pureness of the separate compounds was checked using TLC and melting point analysis. Rf values were the determined from the TLC plates and calculated to compare the experimental Rf values to the starting mixture Rf values. TLC is useful to separate tiny samples and is considerably quick, while chromatography is used to separate considerably larger mixtures but takes more time. The melting point of both desired molecules was found and contrasted with the actual values. The melting point is used to assess the purity of each compound recovered. Column chromatograpahy separates compounds based on polarity. Column chromatography contains a mixture dissolved in solvent and put in a column that had solid adsorbent and an eluent. There are different phases in the column: a polar stationary phase (solid adsorbent), the alumina, and mobile phases (eluent), which can flow throughout the column. There are different phases due to different polarities, resulting in dissimilar bands. TLC separates compounds due to polarity. Each sample is dotted on the plate and placed in eluent and the samples quickly separate due to polarities and adsorption. The spots can either move far or short distances. The weakly adsorbed compounds move faster than the stronger adsorbed components. The textbook mentions simple elution stepwise elution to elute each fraction in the column chromatography. Simple

Dispense .5 mL water into the already weighed conical vial, replace cap and face insert on its down side.

Minerals are naturally occurring, inorganic, solid, crystalline substances which have a fixed structure and chemical composition. Minerals are an important part of Geology, especially when studying Crystal and mineral growth. Understanding how crystals grow and the difference between slow and fast cooling rates is also important in Geology. Knowing the difference between cooling rates is important because cooling rate changes the texture of rocks and minerals. The purpose for the Crystal Growth experiment is to identify which Solubility and temperature produces larger crystals, and to simulate natural crystal growth. We will achieve the results we desire by conducting the experiment thoroughly and correctly, as well as correctly

Crystals were collected in a Buchner funnel, washed with alcohol, then ether, then transferred into a sample tube for storage.

Subsequently, 10mL of 3.5% H2O2 were added dropwise to the reaction mixture and was stirred for 20 minutes before heating to boiling at 80°C for 5 minutes. The reaction mixture was then taken off heat and allowed to cool undisturbed in an ice-bath for 30 minutes. Suction filtration was performed after to collect the crystals from the chilled solution The product was then washed with chilled 95% ethanol (2 x 15mL) and followed by diethyl ether (2 x 10mL). The crude product was then left to dry before recording the yield. 20mg of the crude product is then accurately weighed out and dissolved in deionized water in a 25mL volumetric flask. Deionized water was added to the volumetric flask to the mark and the UV-vis absorption spectrum of the crude product was recorded.