Chem 1A Experiment 3 Lab Report

Chem 1A Experiment 3 Lab Report - Lance Lee, Prof. Nitsche...

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Lance Lee, Prof. Nitsche Chemistry 1A 3-7-08 Revised Experiment 3: Molecules and Light Purpose Determine how effective a sunscreen product is by measuring the extinction coefficient of its active ingredients. This was done in order to compare the extinction coefficients of various SPF factors and see how well they absorb UV light. In Investigation 2, the purpose was to find out whether the brand and/or the SPF value affect how well sunscreens work. Methods The first Investigation required diluting a stock solution, Walgreens SPF 15 (0.08525 g/L) into 6 tubes. Each tube contained 6 mL of stock solution and 95% 2-propanol at varying amounts. These 6 tubes, plus a blank solution (mL 95% 2-propanol) were tested inside the spectroscopy to determine the extinction coefficient of the sunscreen products. The spectrometer measured the absorbance of the solutions and printed the results on a spectrum. After calculating the concentrations of the 6 tubes (by using: C = (mL stock solution) * (0.0852 g/L) * (1L / 1000mL)), a plot graph was made comparing the Concentration with Absorbance (given by the spectrometer). A linear regression was used to record the value of the extinction coefficient (E) which was the value of the slope. The second Investigation explored the effectiveness of sunscreens using UV sensitive
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Chem 1A Experiment 3 Lab Report - Lance Lee, Prof. Nitsche...

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