Essay on Lab1: Effect of Ph on Food Preservatives

The original 1.0 gram of the 50/50 mixture of the benzoic acid and benzil contain 0.5 gram of benzil. Thus, from 0.5 gram of benzil, only 0.266 gram of benzil was collected. The percent recovery of benzil was calculated to be 53.2%. This low percent recovery could be due to filtration errors. Some amount of benzil remained on the filtration paper that contained the MgSO4. In order for determining the purity of the

In order to find the pH of each household item by using pH paper, the pH paper was placed on the drop plate. Using the dropper, start by having the household item dropped onto the pH paper. Immediately observe in order to spot any colour changes on the pH paper. To determine the pH by using the pH scale and record the pH on your table of observations. Depending on what the pH is, it could be very acidic, basic or neutral. Repeat these steps for the other products.

The hydrobenzoin (meso) product of the benzil was isolated through the techniques of recrystallization and vacuum filtration. Because there NaBH4 was the limiting reagent in the experiment, 0.005604moles of NaBH4 should yield 1.2008g of hydrobenzoin (meso). The mass of the isolated product was 0.613g, resulting in a 51.1% yield. There are many reasons to account for the loss of 48.9% of

In the first acid extraction of benzocaine, the compound was dissolved in the organic solvent of dichloromethane. When the mixture was shaken with HCl, benzocaine’s amine group gained a proton and became more soluble in water than dichloromethane. This allowed the newly formed hydrochloric salt to migrate to the aqueous layer. However, the addition of NaOH to the acidic aqueous layer regenerated benzocaine by deprotonation, making it insoluble in the aqueous layer. The precipitation of an ionic salt was therefore recovered by vacuum filtration and had a tested melting point range of 85.1C-87.4C compared to 88C-90C, the literature melting point of benzocaine. The similarity in melting point ranges, but low percent yield of 30.37% proves that the extract was somewhat successful. Lower yields may be the result of spillage performed in the lab. In the second basic extraction, the organic layer now included benzoic acid and benzamide. When treated with NaOH to deprotonate benzoic acid, the newly formed sodium benzoate transitioned to the aqueous layer as a sodium salt. Benzoic acid is regenerated once again after the addition of HCl and became insoluble in the aqueous layer after protonation. Its precipitation was then filtered out for a 65.87% recovery. Compared to its literature melting point of 122.41C, the resulting 120.9C-123.5C melting range of the sample also supports the accuracy of the separation due to its similarities and high percent yield. In conclusion, the usage of base and acid liquid extraction was mostly successful in this experiment because it was able to efficiently and properly isolate the impure mixture into two separate components of benzocaine and benzoic acid. By performing the techniques of extraction and vacuum filtration, the similarities between literature and tested

In order to isolate benzoic acid, benzocaine and 9-fluorenone, each component needed to be separated from one another. All three compounds began together in one culture tube, dissolved in methylene chloride and formed into a homogenous mixture. In this culture tube, two milliliters of aqueous three molar hydrochloric acid was added, which immediately formed two layers, the top acidic aqueous layer was clear in color and contained benzocaine, and the bottom organic formed was yellow and contained benzoic acid and 9-fluorenone. Benzocaine’s amino group is protonated by the aqueous layer hydronium. This protonation forms the conjugate acid of benzocaine, benzocaine hydrochloride. Thus, the conjugate acid, benzocaine hydrochloride is a salt in which is soluble in water and furthermore can be isolated from the organic mixture. When testing out the pH levels in benzocaine, the pH test strip was dark blue in color, indicating a pH level of around 5 to 7. When isolating benzoic acid, two milliliters of aqueous three molar sodium hydroxide was added, which deprotonates the carboxylic group in benzoic acid, forming its conjugate base, sodium benzoate. As with benzocaine hydrochloride, sodium benzoate is a water soluble ionic salt in the aqueous layer that can then be separated from the bottom organic layer containing the 9-fluorenone. The pH test strip was a vibrant red for benzoic acid, indicating a pH of 2. Now the 9-fluorenone is left, deionized water is added to remove any excess

Catechol, in the presence of oxygen is oxidized by catechol oxidase to form benzoquinone (Harel et al., 1964). Bananas and potatoes contain catechol oxidase that acts on catechol which is initially colorless and converts it to brown (Harel et al., 1964). In this experiment, the effect of pH on the activity of catechol oxidase was conducted using buffers ranging from pH2 to pH10. Two trials were conducted due to the first trial results being altered by an external factor. The results were acquired by taking readings every 2 minutes for 20 minutes from a spectrophotometer and then recorded on to the table. The data collected in the table were then made into graphs to illustrate the influence of pH on the catechol oxidase catalyzed reaction. After analysis, the data revealed that pH did have a significant influence on the enzyme as recorded by absorbance per minute. However, the data was collected was not accurate due to external factors, thus the results are debatable and should be experimented again for validation.

Experiment 4A: Determination of a Partition Coefficient for Benzoic Acid in Methylene Chloride and Water, and Experiment 4B: Solvent Extraction I: Acid-Base Extraction Using the System Benzoic Acid, Methylene Chloride, and Sodium Bicarbonate Solution

Stoichiometry and Determining the Limiting Reagent Abstract: Four chemical reactions will be done using different ratios of mixture between calcium chloride and sodium carbonate. The mixture of these two substances produces the precipitate calcium carbonate, which will be separated using filtration. After observing the tubes and collecting data, the limiting reagents were deduced from observing which amount of substance had the least amount of moles. It was found that in trials one through three, the limiting reagent was calcium chloride and in trial four, the limiting reagent was sodium carbonate.

The reaction took place in a conical vial and .2mL of each of the reactant samples were added to it along with some 95% ethanol. Two drops of NaOH were added shortly after and stirred at room temperature for fifteen minutes. The vial was cooled in and ice bath and crystallized. Vacuum filtration was performed to filter the crude product. The crude product was recrystallized using methanol and filtered again. We made one change to the procedure and instead of using .7mL of ethanol we

In this lab, extraction was use as method for separating a mixture of compounds. Specifically, Benzocaine and Benzoic Acid were individually isolated from a starting mixture which consisted of both components. A percent recovery was found for both. The percent recovery found for the benzocaine was 1%, while the percent recovery for benzoic acid was 35%. These low percentages are result of errors during the experiment. One source of error was during the separation of layers. When separating the two layers, some of the top aqueous layer flowed out with the bottom layer. This happened in all of the separation steps, and caused slight impunity in the compounds. This error could have been prevented by more concentration during this part of the experiment.

The purpose of this lab was to learn how to perform liquid-liquid extraction in order to isolate benzocaine and benzoic acid from a mixture. The initial mass of the impure mixture of benzoic acid and benzocaine was 2.143 g. At the end of the experiment, 0.244 g of benzocaine was obtained, and 0.411 g of the benzoic acid was obtained. The melting point range for the benzocaine was 88.6 degrees Celsius to 90.4 degrees Celsius. The melting point range for the benzoic acid was 122.3 degrees Celsius to 125.6 degrees Celsius.

After the initial mixture has refluxed, 9.11 grams of benzophenone was dissolved in 100 mL of anhydrous ether in a beaker and was then transferred into the separatory on the reflux apparatus. This solution was then added to the Grignard reagent at a drop wise rate while stirring. After the benzophenone was added, the mixture was then refluxed for 15 minutes on a heating mantle.

The pure benzocaine was dried, weighed, and percent yield of the reaction was calculated. Besides, the melting point of the white solid was also determined to confirm the purity of the product. The melting point was turned out to be around 88-91°C which was very close to the expected melting point (88-90°C). One of the problem in isolating and purifying the product was during the recrystallization process.

Adding a base or alkali raises the pH of the pool water. If the total alkalinity is normal, pH increaser should be added according to the instructions on the containerbefore trying to increase the pH.

14. The precipitated benzoic acid was filtered using a Buchner funnel and a flask and 5ml of cold distilled water was used to wash.