Estimation of Ascorbic Acid

The mass of ascorbic acid neutralized is given by multiplying the calculated moles of ascorbic acid used (0.00235128 mol) with the molas mass of ascorbic acid (176.1 g/mol).

4. It would be difficult to measure the concentration of acid in red wine or coca-cola because the colour of the drink is too dark for us to see when the phenolphthalein indicator changes colour. You could overcome this difficulty by using a pH meter.

(0.074 mol HCl x 1 mol NaOH) / 1 mol HCl = 0.074 mol NaOH

In Part C of the experiment, the process completed in Part B was performed again on the six Kool-Aid drink samples: black cherry, cherry limeade, grape, mixed berry, strawberry, and tropical punch. The cherry limeade, grape, mixed berry, and tropical punch samples were undiluted stock solutions that were used in the SpectroVis. The black cherry solution was diluted with a 2-fold dilution. The 3 mL of black cherry solution was diluted with 3 mL of deionized water. This was done because the Red 40 dye was too concentrated. The strawberry solution was first diluted by a 2-fold but the absorbances values were too high and fell outside the acceptable range of 0-1. Therefore, 8 mL of strawberry solution was diluted with 12 mL of deionized water. These values for all of the solutions were recorded in Table 5. The solutions were emptied down the sink. All the glassware and cuvettes were rinsed with deionized water and dried. The volumetric flasks and caps were returned to the appropriate containers.

The lab leaders and the Punk Rock Warlord prepared three different concentrations of catechol oxidase by extracting potato juice (because it contains lots of catechol oxidase). Pure catechol, a 5mL test tube, 1mL/5mL

Cider: T1 = 4  C T2= 65C Cp= 3.651 kJ/kg C Mass = 150 kg

Table 2: Consists of color extract taken from a red cabbage for a natural indicator. The pH reading that was measured by using the pH meter and the result of the pH reading to determine whether the solution was acidic or basic.

The titration worked well and yielded decent results. It was found that 72.10 mg of ascorbic acid is contained within a serving of lemonade.The %w/w of ascorbic acid is .30%. The volumes collected and observations made worked out to give proper and expected values. Rinsing the burette and pipette was important to this as it removed any water or dust inside. This meant that final volumes and calculations were more precise as there were fewer sources of error. The standard deviation obtained from the four trials was 0.22 mL. Much of this error is due to the rapid colour change. This made it difficult to precisely end the titration when the endpoint was reached. Another source of error is found in the assumption that because a colour change happened the proper reaction had occurred. This assumption while very basic and small potentially had a slight impact on final results. Titrations are very simple and therefore are empirical, and based off simple measurements with these simple assumptions accuracy decreases and error

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.

Acetic Acid (2 mL AA) ( 1.049 g AA) (1 mol AA) (1 mol product) (130.19 g product)

During a titration the pH of the solution will be monitored using a pH meter from that we get a titration curve. The titration curve is then used to determine the equivalent molecular weight and Ka value of the unknown weak acid, from that we are

The experiments involved PH buffers of different pH were added to potato juice, water, and the enzyme catecholase. The mixture was then subjected to spectrophotometer at a wavelength of 420nm taking the absorbance readings. In the second experiment, a phosphate buffer of PH 7.0 was used in different measures together with different measurement of potato juice and the enzyme catecholase then subjected to the spectrophotometer at a wavelength of 420nm. The data collected inform of table and analyzed using descriptive statistics such as line graph and later interpreted, showing that PH and enzyme concentration do affect the rate of enzyme reaction

The enzyme catechol oxidase, extracted from masticated potato (Solanum tuberosum) lowers activation energy, as it is a catalyst. This enzyme can react with catechol to produce benzoquinone and water. Catechol oxidase is tested against a multitude of phosphate buffers, acidic, neutral and basic pH values, and chilled temperatures to hot temperatures. The purposes of these testes were to determine the optimal temperature and pHs at which catechol oxidase performs at. The method to measure results was the usage of a spectrophotometer (Vernier Spectrouis Plus). The spectrophotometer measures the absorbance levels of the pigment excreted when catechol oxidase undergoes a reaction. The high the absorbance, the more products produced and vise versa. The highest absorbance for the catechol oxidase submitted to different temperatures measured an average 0.6018 nm, when at 20 C. The highest absorbance for the catechol oxidase submitted to different pH values measured two averages of 0.658 at pH 6 and 0.6464 at pH 7. The conclusion taken from the available data explains that the optimal pH for catechol oxidase was between pH 6 and 7 and the optimal temperature was at room temperature at 20C.

4g of Na CO x 1 mol of Na CO 4g of CaCl x 1mol of CaCl

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.