Trizma Case Study Chemistry

1. We measured 2 mL of diluted hydrogen peroxide (the substrate), 1 mL of guaiacol (the product indicator), and 1 mL of neutral buffer (pH 7) with a syringe and disposed it into tubes 1, 2 , 4, 9, 11, and 12.

Procedure: I used a ruler, thermometer, and scale to take measurements. I used a graduated cylinder, short step pipet, scale, and ruler to determine volume and density. I used a volumetric flask, graduated pipet, pipet bulb, scale, and glass beaker to determine concentrations and densities of various dilutions.

A hot plate was preheated to 100°C. A dry 5-mL long-neck round-bottom flask was clamped over an aluminum block placed on the hot plate. Ferrocene (0.09 g), acetic anhydride (0.35 mL), and 85% phosphoric acid was added to the flask in that order of addition. A magnetic stir bar was added to the flask. Solution was stirred and heated for 10 minutes. Flask was removed and allowed to cool to ambient temperature. DI water (0.5 mL) was added and the solution was cooled to 0°C by ice bath. The solution was neutralized with 3M sodium hydroxide dropwise while stirring and cooling. PH was monitor by pH indictor paper. Solid product was isolated by vacuum

The purpose of the experiment was to determine how a buffer works and how to use an acid-base indicator. The way a buffer works was determined by observing the changes in pH of solutions of different concentrations weak acids and their conjugate bases to determine how a buffer affects the pH change. The solution of 10 mL of 0.20 M CH3COOH and 10 mL of 0.20 M CH3COONa had slighter changes in pH than the solution of 10 mL of 0.0020 M CH3COOH and 10 mL of 0.0020 M CH3COONa. Both of these solutions were buffers, shown because they had slighter changes in pH than the solutions with only the weak acid or conjugate base and water. The determination of how buffers work was also tested with observing that the solution of NaC4H3O4 and Na2C4H2O4 had smaller

To improve the results from the experiment buffer solutions that were not whole pHs could have been used e.g. pH 4.5, 5.5 etc. This would have provided more reliable results as a wider range of results would have been produced. Using pHs with decimals would also help to more accurately determine the optimum pH as the optimum may have been above or below the pH stated in the hypothesis; 8. In this experiment however the optimum is taken at 8 because the graph does not rise again.

Buffers can be used to resist change in pH in an acid or base solution. The purpose of the lab is to understand the properties of buffers in relative concentrations, in the presence of a strong acid/base and dilution of buffer components the ammonia/ammonium buffer system. In this case, these laboratory techniques associated with buffers are performed to determine the pH values in diluted solutions. This is done by observing the Henderson-Hasselbalch equation. This represents the pH value by comparing the p value and the concentrations of a weak acid and conjugate base of a buffer solution, as long as assumptions are valid. From there, a pH vs log can be used from the values obtained. Then, the theoretical pH of solutions can be determined with the addition of a strong acid (HCl) and base (NaOH). From this, the effect of dilution can be viewed when plotting the calculated pH values vs dilution on the same graph.

One milliliter of 6.00-M phosphoric acid was placed into a 125-mL Erlenmeyer flask using a volumetric pipette. Using a slightly larger pipette, six milliliters of 3.00-M sodium hydroxide was transferred into a 50-mL beaker. Then a disposable pipette was used to slowly mix the sodium hydroxide into the phosphoric acid while the solution was swirled around. Then both the beaker and flask were rinsed with 2-mL of deionized water and set aside. A clean and dry evaporating dish was weighed with watch glass on a scale. Then the solution was poured into the dish and the watch glass was placed on top. The solution was then heated with a Bunsen burner to allow for the water to boil off to reveal a dry white solid. After the dish cooled to room temperature it was once again weighed and the new mass was recorded.

The solution has been dechlorinated and adjusted to be slightly acidic. Place 75 mL of the solution in each of three labeled beakers. Obtain an animal organism, small fish, and a plant organism, Elodea. One beaker will be the control and will not have anything in it. Place exactly 25 mL of water in a 50-mL graduated cylinder. Place each organism in a cylinder and note the increase in volume above the original 25mL. The increase equals the volume of the organism. After taking measurement, cover each beaker with the plastic film. Place the beaker containing the Elodea in the dark by covering it with aluminum foil. Allow organisms to respire for 15 min. Gently remove the organisms from the beakers and return them to their original culture bowls. Then add four drops of phenolphthalein to the contents of each beaker. The solutions should remain clear because the solutions are acidic. Using a dropper bottle, dispense NaOH into the contents of the beaker drop by drop. Thoroughly mix the contents of the beaker after adding each drop. Continue adding drops until you first notice that the solution turns pink. Repeat for each beaker with at the living organism until the solution is the same shade of pink as the

In this experiment, a saturated calcium sulfate was already made and ready to use. 25.00 mL of this solution was then mixed with 10 mL of an ammonia buffer and 1 drop of

The samples were prepared in vials with one milliliter of methanol and one microliter of sample. Every sample is run under each condition three times with ten microliters being injected each time. The flow rate is set at one milliliter per minute and the temperature is maintained at 20oC. The log of retention times

For this experiment, titrations on a weak acid, acetic acid, and a buffer were performed. Acetic acid was titrated with NaOH in order to observe the half-equivalence point as well as the equivalence point. Then, the buffer and the buffered acetic acid solution prepared faced additional titration with NaOH and HCl to evaluate the differing buffering effects following the addition of a strong acid and strong base. Finally, the buffer’s buffering capacity was calculated. If the experiment were to be repeated, it would be interesting to observe the buffering effects following a titration between a weak base and a buffer instead with greater concentrations. The change in the concentration following the preparation of buffer with a weak base and its conjugate acid would pose for an interesting experiment to observe an increase in the buffering capacity.

The first experiment begun by filling a 600-ml beaker, almost to the top, with water. Next, a 10-ml graduated cylinder was filled to the top with water. Once water was added to the beaker and graduated cylinder, a thumb was placed over the top of the graduated cylinder. This would ensure that no water was let out and no bubbles were let into the graduated cylinder. Next, it was turned upside down and fully submerged into the beaker. Then, a U-shaped glass tube was attained. The short end of the glass tube was placed into the beaker with the tip inside of the graduated cylinder. Next, a 50-ml Erlenmeyer flask was received. After, 10-ml of substrate concentration and 10-ml of catalase/buffer solution were placed into the flask. A rubber stopper was then placed on the opening of the flask. After adding these, the flask was held at the neck and spun softly

To perform module 9 analysis, we followed Lab safety procedure by wearing safety goggles (Z87 brand), plastic apron, and a pair of latex gloves as a proper “PPE”. The team proceeded to gather module 9 analysis equipment which consisted of; an Oakton PCS tester 35 series, a HACH HQ40d portable multi-meter, a HACH digital titrator with Sodium thiosulfate titration cartridge 0.200 N, and delivery G tube. Furthermore, a stand ring with universal clamp, magnetic stirrer with magnetic stir bar, 1 Plastic Graduated cylinder (100 ml), 2 Plastic sample containers (250 ml), 2 Glass BOD Bottle (300 ml) with stopper, dissolved oxygen reagent powder pillows (2 Manganous Sulfate, 2 Alkaline Iodide-Azide,2 Sulfamic Acid powder pillows), and nail clipper. 1 Erlenmeyer flask (250 ml), Buffer standard solution for pH (4.0, 7.0, and 10.0) and Conductivity (12880µS), starch indicator solution, DI water bottle, Kim wipes. Upon gathering, we set the Lab data sheet, COC sheet, pencil, and calculator.

For this experiment, a pH meter was used so this part of the experiment began with the calibration of the pH meter with specified buffers. The buret was then filled with the standard HCl solution and a set-up for titration was prepared. 200g of the carbonate-bicarbonate solid sample was weighed and dissolved in 100 mL of distilled water. The sample solution was then transferred into a 250-ml volumetric flask and was diluted to the 250-mL mark. The flask was inverted several times for uniform mixing. A 50-mL aliquot of the sample solution was measured and placed unto a beaker. 3 drops of the phenolphthalein indicator was added to the solution in the beaker. The electrode of the pH meter was then immersed in the beaker and the solution containing the carbonate-bicarbonate mixture was titrated with the standard HCl solution to the phenolphthalein endpoint. Readings of the pH were taken at an interval of 0.5 mL addition of the titrant. After the first endpoint is obtained, 3 drops of the methyl orange was added to the same solution and was titrated with the standard acid until the formation of an orange-colored solution. Readings of the pH were also taken at 0.5 mL addition of the titrant.

To prevent fluctuation in the pH, a solution known as a “buffer solution” was used in the experiment. Buffer solutions are mixtures of at least two chemicals which counteract the effect of acids and alkalis. Therefore, when a small quantity of alkali or acid solution is added the pH of the enzyme doesn’t change.