In the second step, the addition of sodium borohydride reduced the imine into another derivative, which was yellowish lime color. The solution turned clear when acids and anhydrides was added, which indicated the precipitate were dissolved. However, after refluxing for a while, yellow precipitates begin to form near the top of the flask. It was assumed that the remaining starting material was concentrated from a decrease volume to reappeared in solution. Nevertheless, this may have been a sign of contamination that will negatively affect the entire reaction.
To begin, the B. Vulgaris samples were put into vials containing the distilled water, 40% and 70% Ethanol solutions. As soon as the B. Vulgaris samples were added to the vials a time zero sample was taken from the vials. 3mL of the liquid in each of the vials were added into cuvettes and measured in the spectrophotometer. Before each time point the photo spectrometer was zeroed using a cuvette with 3mL of distilled water. If any of the results were considered unusual the machine was zeroed again and the sample was retested.
Because it is a tertiary benzylic halide, the reaction is considered an SN1 type. To test the purity, the class then uses a TLC. When one places,” a spot of the substance on the absorbent surface of the TLC plate, the solvent (or solvents) run up through the absorbent,” (Zubrick223). The initial mass of the reactant, triphenylmethyl chloride was 2.006 grams. The experiment yield is 1.589g, which is a 80.3% yield.
In this lab, the oxidation of a secondary alcohol was performed and analyzed. An environmentally friendly reagent, sodium hypochlorite, was used to oxidize the alcohol, and an IR spectrum was obtained in order to identify the starting compound and final product. The starting compound could have been one of four alcohols, cyclopentanol, cyclohexanol, 3-heptanol, or 2-heptanol. Since these were the only four initial compounds, the ketone obtained at the end of the experiment could only be one of four products, cyclopentanone, cyclohexanone, 3-heptanone, or 2-heptanone. In order to retrieve one of these ketones, first 1.75g of unknown D was obtained.
One error that could have affected the percent yield is not filtering out all of the liquid from the filter paper in the funnel before setting it off to dry. This would have increased the final mass of the solid, not making it accurate. To stop this from happening again, the liquid could be drained more thoroughly until it fully stops dripping into the Erlenmeyer flask. Another error that could have affected the percent yield is the amount of trials performed. This would have made the results less accurate and made any errors change the final results even more.
Purpose The purpose of the experiment was to determine the molar mass of unknown solute number 1. This was done by using colligative properties of solutions specifically, freezing point depression. Colligative properties depend on the number of molecules that are present in the solution rather than the nature of the molecules . This fact is useful because knowing this allows one to use the properties of the number of molecule in the solution without needing to worry too much about the nature of the molecules. Using this knowledge, the experiment consisted of freezing cyclohexane over 4 trials, 3 trials involved increasing amount of salt while the first was pure cyclohexane.
. Before solution application, the HPTLC plates were sprayed with 10% (w/v) disodium ethylene diaminetetraacetic acid (Na2EDTA) solution in which the pH had been adjusted to 4 using glacial acetic acid. This Na2EDTA solution helps to avoid binding of the tetracyclines with trace metals in the adsorbents used . Since OTC and TC have similar chemical and physicochemical properties they form chelate complexes with metal ions and bind with proteins and silanol groups in the stationary phase. These undesirable properties have been controlled by the use of EDTA for plate treatment .
In addition, phenolphthalein was added as an indicator. The aliquots were titrated against sodium hydroxide (NaOH) solution until end point was reached, after which volume of NaOH consumed was recorded. The value of the rate constant, k, obtained was 0.0002 s-1. The experiment was then repeated with 40/60 V/V isopropanol/water mixture and a larger value of k = 0.0007 s-1 was obtained. We concluded that the rate of hydrolysis of (CH3)3CCl is directly proportional to water content in the solvent mixture.
We added 1 ml of distilled water to test tubes labelled 2, 3,4 and 5. . To tube 1 we added 1ml of standard protein solution and recorded the concentration of the standard protein as 10mg/ml. To tube 2 we added 1ml of standard protein solution and shake it so that it can mix well. With a fresh pipette we removed 1ml from tube number 2 and added it to tube 3 then gently shake the tube. With another fresh pipette we removed 1ml from tube 3 and added it to tube 4, shake well.
• Carefully decant the solvent solution from the drying agent through the funnel into the flask. Rinse the Erlenmeyer flask with about 10 ml of solvent and pour the solvent through the funnel, too. Remove the funnel, add two or three boiling chips and reattach the thermometer and adapter to the still pot. • Discard the magnesium sulfate remaining in the Erlenmeyer flask by dissolving it in tap water and pouring the solution down the drain. • Before beginning the distillation, weigh a clean, dry 1 narrow mouth screw cap bottle on a balance.
32 100 μL of afore-prepared sample solution and the mixed reference standard were diluted 100 times with ethyl acetate. 50 μL of these dilution solutions were separated on the TLC plate coated with SNISG. The plate was developed with petroleum ether: ethyl acetate (4:1) and the movement of solvent was usually controlled at 1 cm from the upper edge. After completion, the plate was dried until no solvent smell remained. It was sprayed with an ethanol solution containing 10% sulfuric acid, and heated at an infra-red drier until obvious color came up, as shown in Fig.2 (B.ab).
The purpose of this experiment was to create two 40 mL buffers and evaluate its buffer capacity at pH 4. To do this, buffer #1 consisted of the mixture of 0.5003 M acetic acid and .50 M sodium acetate, while buffer #2 consisted of the mixture .5003 M acetic acid and .4289 M NaOH. Within each mixture, there is a ratio of conjugate acid to conjugate base. By using the Henderson Hasselbalch equation, the volume for the base and acid to buffer the pH of solution at 4.0 were calculated. Two titration were performed for each buffer: HCl and NaOH.
What happens during this stage of the experiment showing visual change and acidic reaction that is becoming weaker as the molecules are deprotonated to become equal parts within the solution. So by finding the molar ratios we learned that acid to base are 1:1 when equally balance or concentrated. So therefore concentrations at stoichiometric end point can be found by plugging in the values to formulate a dilution equation as seen above. When expressing calculations I found when doing the Titration of an Unknown Acid I discovered that with .1 mL of Sodium Hydroxide and at least 10 mL Anthocyanin as/or acetic solution will produce an average molarity of 0.9 or higher according to my
The main purpose for this experiment was to become familiar with the differences of elements, mixtures and compounds. The lab consisted on performing four different tests on both Iron (Fe) and Sulfur (S). If the four experiments were performed on each element then their would be a different reaction for each. The first test consisted of simply laying out a certain amount of each element of a piece of paper and observing the reaction when a magnet was placed on the bottom. The second test consisted on mixing in a 100ml beaker, 30ml of water and the respective amount used in the previous step of each element and analysing what the reaction was.
During plating, drops of the Excedrin solution may have been introduced to the plate. Also, the capillary tube may have been contaminated. This lead to nearly identical marking on the TLC plate and similar Rf values. Due to this, it is not possible to conclude whether or not acetaminophen was separated from the sample of Excedrin. The Rf value of the pure isolated caffeine was 0.28.