Goals: For this laboratory, the main objective was to determine the phosphate content of three different colas and compare the three. To start, the first goal was to learn and become better educated on the function of the Spec-20. The next goal was to determine the relationship between color and wavelength of absorbance by using the Spec-20. The group was to measure each color at different wavelengths, and determine the absorbance rate at each level. The next goal was to determine the relationship between absorbance and concentration by obtaining the analytical wavelength, and creating a calibration curve. Finally, the last goal to finish the project was to determine the amount of phosphoric acid in the cola beverages. The phosphoric acid content …show more content…
Before any of the dilutions could be completed with the phosphate, it had to be diluted from .0001 Molarity, to a .0002 Molarity. The overall process was done by mixing the phosphate solution with an acid called AVM, and then measuring the percent transmittance. The percent transmittance for these dilutions had to be between 15% and 85% as well. In order to dilute the phosphate concentration, the first step was to use a volumetric flask to properly dilute the solution at a 3:1 ratio. The phosphate solution was diluted with water, by adding 75% of the phosphate, and 25% water, creating the 3:1 ratio. After diluting the phosphate solution, the AVM was added to the solution at a 2:1 ratio. There would be twice as much of the phosphate solution than the AVM. The reason the AVM had to be added to the solution is because the phosphate solution is colorless, so in order for it to be measured in the Spec-20, there would need to be some sort of color in the solution. The AVM provided the phosphate solution with a yellowish tint. Next, the group used the same steps to dilute the already diluted phosphate solution. After creating the second dilution, which gave the phosphate a .00015 molarity, it was recognized by the instructor that the Spec-20 provided had not been properly calibrated. Due to the improper calibration of the Spec-20 and a restraint for time the dilutions had to stop there. Because the Spec-20 had not been properly calibrated, it caused the data for week two to be fairly skewed. In order to obtain proper data, the instructor supplied reference data to be used for the majority of week two. The main issue faced during the second week of lab was having trouble making the dilutions properly. However, it was not noted until later that the reason the dilutions weren’t creating proper readings in the Spec-20 is because it had not been calibrated. The
Data from Table 1. confirms the theory that as the concentration of glucose increases so will the absorbance of the solution when examined with the glucose oxidase/horseradish peroxidase assay. Glucose within the context of this assay is determined by the amount of ferricyanide, determined by absornace, which is produced in a one to one ratio.1 Furthermore when examining the glucose standards, a linear calibration curve was able to be produced (shown as Figure 1). Noted the R2 value of the y = 1.808x - 0.0125 trend line is 0.9958, which is statistically considered linear. From this calibration curve the absorbance values of unknowns samples can be compared, and the correlated glucose concentration can then be approximated.
The essential points of the green-frosting are the concentration and absorbance value in each diluted which the process of serial dilution. The standard curve of Blue#1 and yellow #5 provide the equation of the trend-line in order to calculate the concentration in the diluted solution of the green frosting. The mole of dye in 100mL green stock solution, mole of dye in 5 gram and 1 gram of frosting, the Beer –Lambert Law, and the compare to amount desired by the company can be determined. The Beer-Lambert Law is the relationship between color and the concentration and equation A=Ebc. The “A” is absorbance, the “C” is a concentration in molarity, the “E” is a molar absorptivity and “b” is the path-length. The goal of the lab is to use the absorbance and the Beer-Lambert law to determine the amounts of blue#1 and yellow #5 in the green frosting.
We then took 1ml of the 0.1% solution from test tube 2 using the glucose pipette and added it to test tube 3, we then used the H2O pipette and added 9ml of H2O into test tube 3 creating 10ml of 0.01% solution.
During week 1 of this experiment, we recorded common components of fertilizers and then went on to find the chemical formulas involved in creating them. The second week we began the process of comparing three authentic ions we had established in the first week to ion samples to discover other properties they might contain. We decided to discover these different ingredients by preforming a serious of tests, which included placing 0.2g solid of both the authentic and the sample fertilizer separately, in order to establish a constant, and dissolved the fertilizer in 20 mL of water, then checked to see if Mg was present in the sample solution. By setting up a constant and preforming a methodical experiment all on the samples given, we demonstrated the ability to correctly establish and preform an experiment and solve the problem at hand, which was distinguishing the contents of the authentic
We were then to make a base solution of 0.7 M NaOH. In order to standardize
The independent variable for this experiment is the enzyme concentration, and the range chosen is from 1% to 5% with the measurements of 1, 2, 4, and 5%. The dependant variable to be measured is the absorbance of the absorbance of the solution within a colorimeter, Equipments: Iodine solution: used to test for present of starch - Amylase solution - 1% starch solution - 1 pipette - 3 syringes - 8 test tubes – Stop clock - Water bath at 37oc - Distilled water- colorimeter Method: = == ==
This objective required us to calculate the densities of both sodas and determine which of the three pieces of glassware used, beaker, graduate cylinder, or buret, was most accurate and which was most precise. The pooled class data revealed that the buret was the most accurate for both Coke and Diet Coke. The actual density of Coke is 1.038 g/mL and the buret had a density of 1.041 g/mL, which is 0.003 g/mL greater than the actual density. This density was the closest to Coke. The density of Coke with a beaker was 0.92 g/mL, which is 0.118 g/mL less than the actual density and the density with the graduated cylinder was 0.998 g/mL, which is 0.04 g/mL less than the actual density. The actual density of Diet Coke was 0.997 g/mL and the buret was closest with a density of 1.006 g/mL, which is 0.008 g/mL greater than the actual density. The beaker gave a density of 0.87, which is 0.128 g/mL less than the actual density, and the graduated cylinder gave a density of 0.945 g/mL, which is 0.053 g/mL less than the actual density.
Secondly all dilutions were made by hand, not included into the raw data was a multitude of errors which occurred when the dilution was prepared wrong. Potentially the dilutions were prepared correctly, and rather the solutions were not uniform in nature. For example the way the dilution occurred was if the required molarity was 0.05 of A and the supplied was 0.2 molar of A. 10 ml of A could be taken and 10 ml of water could be added, to make a 20 ml 0.1 molar solution of A. Next take 10 ml of the new solution and add 10 ml of water, and the 0.05 molar solution of A is formed. The flaw is thought to be in the third part of the procedure, as 0.1 molar of A is thought to have been taken out of the second solution but rather the 0.2 molar has not been correctly mixed through, and as such the final molarity is not what was calculated. This effects all the data found as the majority of points found used dilution which potentially were not correctly performed.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Start to prepare the sample in a 10mL (10000µm) place 0.4mL (400µm) of the stock Ferritin solution 0.5g/mL in 0.15M sodium acetate (AcONa). Afterwards add 0.8mL (800µm) at 2M of sulphuric acid (H₂SO₄) and 0.8mL (800µm) at 5mM of dihydroxyfumarate (C₄H₄O₆). Wait for 30 minutes then complement the solution with 1.6mL (1600µm) at 2.5M of sodium acetate (NaOAc) followed by 0.8mL (800µm) at 12.5mM ferrozine (C20H12N4Na2O6S2). Lastly wait another 30 minutes afterwards add distilled water using a stopper to complete the solution to 10mL (10000µm) then put the rubber stopper on the volumetric flask and mix till you are sure that all the contents are mixed. Again, set up the spectrometer to 562nm and using the 2 samples that were made take one from each to measure the absorbance plus a third one from either one of the solution.
The main purpose of this research lab was to determine the level of phosphate content within the colas and the relationship with phosphate and upset stomachs. Following, the logic was if the capacity of the phosphate was buffered, this will solve upset stomachs of individuals. However, the amount of phosphate cannot be directly determined so a series of steps and calculations to gain an understanding of the overall project. (Cooper,2008) For starters, proper usage of a spectrophotometer must be mastered, and an understanding the relationship between absorbance, concentration, and percent transmittance must be gained. To gain a complete understanding, three different tests were done with three different samples of food coloring and the determination of the analytical wavelength was completed by using the spectrophotometer.
Setting up the apparatus was quick and easy, but measuring the DCPIP solution took a bit of time because they had to be the same volume so that they don’t affect the results. Although there were variables that were controlled, there was another variable which I did not identify until after our investigations were done.
Pipette the amount seen in below into the respective test tube and placing them individually into the spectrophotometer set at an absorbance of 565nm.
We rinsed the crystals twice with 10 milliliters of water each time. We then split our sample in half and purified one
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.