Aquapentaamminecobalt Synthesis Lab Report

The primary goal of this laboratory is to correctly identify an unknown substance. To achieve this task, one may use various tests that reveal both chemical and physical properties of a substance. By comparing the results of a known substance and the unknown substance, one may eliminate alternative possibilities and more accurately predict the undisclosed compound. Furthermore, by performing these tests, data can be collected and verified regarding chemical and physical properties of the unknown. Understanding the chemical properties of a known substance aids one’s understanding of the unknown based on comparative analysis of the results of the tests.

The mixture might have contained more or less than 5 drops of bromophenol blue, which might have resulted in the indication of the lab.

The decanted liquid had to be placed back into the freezer in order to refreeze the crystals to allow them to be decanted off. This could have caused a portion of the product to have been lost, thus affecting the percent yield and purity of the final product. Furthermore, there was an oiled substance thought to be a contaminant in the product after the addition of hot methanol and hot water to the Erlenmeyer flask. This contaminant was left in the Erlenmeyer flask to see whether or not it had an effect on the final product, but once the activated charcoal was added into the Erlenmeyer flask, the contaminant seemed to have latched onto the charcoal. Since it latched onto the charcoal and the charcoal was filtered out by way of gravity filtration, the contaminant is thought to have been filtered out as well. While the contaminant seemed to have been filtered out by the gravity filtration, there could be a small portion of the contaminant that remained in the filtered-out product, thus affecting the percent yield and purity of the final product as

The pipet was put into the top of the condenser and leaving no open spaces. The vacuum served to get rid of the nitrogen oxide gases that were formed during the oxidation reaction. The solution was heated for 30 minutes, beginning the time when the first sign of nitrogen oxide fumes were observed. After the 30 minutes, the solution was removed and cooled for a few minutes. The solution turned was a brownish-yellow color and all the crystal were dissolved, leaving a liquid. The solution was then transferred, using a Pasteur pipet, to 3 mL of water in a beaker. The reaction flask was rinsed to remove the remainder of the solution. The solution was stirred with a glass rod until room temperature of the solution was achieved. A yellow solid was to form, but instead the solution remained aqueous in the case of the specific experiment explained here. With additional scraping of the solution with a glass rod, no crystals formed at all. The next procedure, if the crystals had formed was to crush the solid with the glass rod and filter the solid until the crystals were dry. The mass would then be weighed and the crystals were to be recrystallized with 95% ethanol. The crystals were to be cooled in ice water to get full crystallization and then the crystals were to be filtered and air dried, then weighed.

For this experiment, I added two chemicals K2CrO4 and HCl together which created an orange color. Then I added NaOH to revert the reaction, which changed the color of the solution back to yellow. I repeated the same procedure but didn’t add the NaOH the second time but added the solution to cold water then hot water for three minutes and observed the reaction. I did the same thing for K4Fe(CN)6 and Fe(NO3)3 except when I mixed them together it produced a dark blue with dark specks solution. I then added NaOH to revert back to the original solution but I got a yellow color with brown specks instead.

In the experiment, Luminol Synthesis and Chemiluminescence, the purpose is to create luminol using the base-mediated reduction of 5-nitro-2,3,-dihydrophthalazine-1,4-dione and to investigate the chemiluminescence reaction that luminol is known for. 5-nitro-2,3-dihydrophthalazine-1,4-dione was reduced using sodium hydrosulfite in a solution of sodium hydroxide under reflux conditions. Acetic acid was used to precipitate the solid luminol product, later the product was collected through vacuum filtration. The luminol product emitted a blue light when a dilute solution of it and sodium hydroxide was mixed with a dilute hydrogen peroxide and potassium ferricyanide solution. The blue light seen correlates to the excited molecules that are dropping

The experiment at hand involved a lot of different steps and goals, yet the entirety of the experiment was aimed at determining the concentration of Ni2+ and Co2+ ions in an unknown solution. Such an experiment is greatly important and has several benefits. First of all, the experiment teaches and reinforces multiple different skills that every scientist should be familiar with, such as using a spectrophotometer, diluting solutions, and creating calibration curves. On a much broader scale, however, the experiment provides a simple and relatively quick way to determine the concentration of an unknown solution. Such a tool is very useful and important in modern society, for a wide variety of reasons; yet determining the toxicity or potential danger of a solution is probably one of the most important uses, whether it be in the lab, medicine, nutrition, or some other field of study.

During this experiment, we carefully examined the unknown compound and followed specific tests and steps to determine the identity of the compound.

If the experiment were repeated it would be important to possibly have students use pipets or some measured method to rinse their product during recrystallization so that mistakes such as over rinsing occur less and are more precise. Also another improvement that could be made is to perform more tests to the acid that had been a nucleophile to better identify its transformation. Other wise the lab that was performed was parallel to that of work in the extraction of medicines and other compounds that are marketed as pure at a less grand scale, but demonstrated the importance of acid/base chemistry.

The difficulties behind the makings of the product was understanding the concept and the purpose behind the enteric program. The hardest part of the that one experiment is that a scientist need to learn how to work with different people consequently, our class being directed to accomplish a lot of planning who will complete what, including: labeling the tubes, makes the agar and Kanamycin, math, spreadsheet, and actually run the CFU.

After the 6M NaOH was added to the solution of Ni2+ and Fe3+ the solution began to form a copper colored precipitate dispersed within the solution. After being centrifuged the nickel settled to the bottom and remained cooper colored.

Next is the percentage yield.  In chemistry, percentage yield serves to measure the effectiveness of a synthetic procedure, (McMurry 2011) but there are reasons why we do not get 100% yield in this experiment. First, not all of the reactants reacted with HNO3, some products are left on the filter paper, and third, some products were dissolved by the wash solvent.

The addition of H+ ions from HCl bonded with NH3 to make NH4, decreasing the concentration of NH3 in the solution. This lead to the reaction shifting towards the reactants, producing more NH3 and [Cu(H2O)4]2+ than [Cu(NH3)4]2+ and H2O, thus changing the colour to light blue. If steps 2

A solution of the salt was prepared and 4 drops of AgNO3 (10%) solution were added. This created an off-white creamy precipitate. In order to be sure that this was not a false positive, three drops of nitric acid (6 M) were added. As the precipitate did not dissolve this meant that the unknown anion had a halide. To confirm which halide it was, a fresh solution of the salt was created and acidified with a few drops of HNO3 (6M). This was accompanied by 1ml of chloroform, an organic solvent. The addition of a few drops of NaOCl solution, swirled gently as the drops made contact with the unknown created a brown-yellow

The next test that was conducted in this lab was the Anion/Cation Test. Within the Cation/Anion test the first experiment was done with the Ammonia Trial. Within this trial,1ml of 6M NaOH was needed along with 0.03g of the unknown compound, and 1ml of distilled H2O. The Ammonia Trial will have a chemical compound of NH4(X) + NaOH => NH3 + Na(X) + H2O, where X is the unknown anion. The first step of this trial was to mix the measured unknown with the H2O. Once the compound has dissolved, add the NaOH to the solution. By wafting over the solution determining if an ammonia smell is present, if so the unknown compound will contain ammonium. The trial was repeated three times and observations were recorded. The next Cation/Anion experiment that was conducted was the Halide Trial. This trial was conducted by taking 0.03g of unknown compound and creating a solution with 1ml of distilled H2O. Then, 1ml of 6M HNO3, and 1ml of 0.1M AgNO3 was added to the solution, and observations were made towards if a white precipitate was formed.