Analysis Of The Concentration Of Phosphoric Acid Content In Pepsi

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PROCEDURE: Hirko, R. Chemistry 112L General Chemistry I Laboratory, Ninth Edition; bluedoor: Minneapolis, 2015; Experiment 4.
Trial P/ppm Abs @ 400 nm / AU Volume beverage / mla Volume dilution water / mla Total volume of diluted sample / mla P in soda / ppm
1 0 .001
2 1.333 .160
3 3.333 .280
4 6.667 .585
U1 2.560 .228 .870 45.610 46.480 205.153
U2 2.607 .232 1.020 50.266 51.386 197.005
U3 3.374 .298 1.196 43.252 49.448 209.244
Ave 204
Unc ±12 RESULTS: The recorded concentrations of phosphoric acid content in Pepsi taken from three trials was found to be 204 ± 12 as listed in Table 1.
Trials 1-4 show the results of the calibration solution which were used to calculate the phosphoric acid concentrations in the Pepsi-Cola.
Trials U1, U2, and U3 were the trials in which the phosphoric acid content was measured using Pepsi brand cola. The P/ppm levels of phosphoric acid in the undiluted Pepsi-Cola were calculated using Equation 1,
P/ppm=(Diluted P/ppm )((Total Vol Dil
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Because the initial trial contained the reagent, and that was set as the baseline, each of the following trials’ reagent was accounted for; therefore, the final absorption numbers subtracted the reagent number and only read the phosphoric acid absorption numbers. Had the calibration trials been performed initially with water instead of the blank reagent, the results would not have been accurate because the reagent itself absorbs some of the light from the spectrometer. Instead, the results would all have had an even higher bias in the absorption values. A larger path length, such as 450 nm instead of 400 nm would increase the absorption numbers due to more molecules in the path of the light. Additionally, this could scatter the light and raise the numbers even more. Equation 2 shows this to be true; as ι increases, so would the absorbance. These would end up with a steeper (larger) slope on the regression

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