Project 13 Preliminary Lab Report - 2017 PDF

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Project 13: Analysis of Colas

Bryson Orosa Syed Hassan Tatiana Bernard

Chemistry 1046 Laboratory, Section U08 Instructor: William Morrison IV October 24, 2017

My signature indicates that this document represents my own work. Excluding shared data and sections, the information, thoughts and ideas are my own, except as indicated in the references.

Discussion This experiment the “analysis of colas” showed the distinctive theoretical relationships of the Beer’s Law. The relationships present included wavelength, color, concentration and absorbance. Prior to conducting the actual experiment, we found the different relationships the first one being between wavelength and color. The relationship of color and wavelength is due to wavelength transmittance through a solution and wavelength being absorbed by the solution which will result the solution color to be opposite. Prior to the experiment the relationship between concentration and absorbance was found also which was inversely proportional to each other as the results show below. In the first part of the experiment we learned how to use the spectrophotometer and find the wavelength of the solutions along with the absorbance. In table 1, we can see the lambda max for all the solution which were found using the instrument. Violet, blue, teal and green all had a lambda max of about 630 nm. Yellow, orange and red all had a lambda max range of 430-502 nm. With the lambda max we also found the percent transmittance red had the highest transmittance of 68.3% and violet had the lowest with about 32.8 %. Since red had a longer wavelength and lowest frequency it had the highest percent transmittance. Violet had a shorter wavelength and a higher frequency it had the lowest percent transmittance. The data in table 1 showed the relationship between color and wavelength and the data had correlation with each other. The second part of the experiment was to perform serial dilutions using potassium permanganate to analyze the relationship of concentration and absorption. From table 2 we can see that Dilution 1 had the highest absorbance and Dilution 5 had the lowest absorbance but Dilution 1 had the lowest concentration and Dilution 5 had the highest concentration. According

to the Beer’s law absorbance and concentration are inversely related to each other and the data presented supports this relationship between the two. The last part of the experiment was to find the calibration curve for an unknown cola which was given to us. We had to perform serial dilutions to calculate the unknown cola phosphate concentration from its absorbance. We used monopotassium phosphate to find the curve the absorbance, Y=9405.9 and concentration x=.0327 with these we formed a linear equation y=9405.9x-.0327. This allowed us to find the calibration curve for the cola. This technique allows to analyze any cola if they are diluted correctly. The technique showed us how to compare a specific concentration in different solutions.

Conclusion This experiment “Analysis of Colas” helped us understand and determine the relationship of several factors. The first relationship between color and wavelength showed that wavelength absorbed correlates to the wavelength of the opposite color of the solution. The second relationship we had found was between concentration and absorbance which were directly proportional and linear to each other. These relationships all fall under the principles of the Beer’s law. There were some error we had in our calculations such as in the table, it showed that teal had a high percent transmittance which was incorrect we believe it could’ve happened due to a source of error in the experiment process it could have been due to contamination or not mixing the solutions. If we were to do the experiment again we would use a fresh Ammonium vanadomalayaite since it was old it could have been dead this had affected in obtaining the absorbances. Other sources of error could have included human error, incorrect measurements and contamination.

References 1. “Michigan State University Department of Chemistry” https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/uv-vis/spectrum.htm (October 10, 2017) 2. “Chemguide” http://chemguide.co.uk/analysis/uvvisible/beerlambert.html (October) 3. Clark, J. (2016, May). THE BEER-LAMBERT LAW. Retrieved October 24, 2017, from

http://chemguide.co.uk/analysis/uvvisible/beerlambert.html

4. Visible and Ultraviolet Spectroscopy. (2013, May 5). Retrieved October 24, 2017, from https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/uv-vis/spectrum.htm

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