FINAL LAB Report FINAL - Spectrophotometric Analysis of...

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Spectrophotometric Analysis of Mixtures: Simultaneous Determination of Two Dyes in Solution Seoiyoung Ahn SID: 23768027 Abstract The objective of the experiment was to figure out the concentrations of Yellow 5 and Red 40 solutions in the food dye and beverage by using spectrophotometry, a common form of analysis used to determine concentrations of certain solutes in solutions, based on the Beer- Lambert Law. After the absorption spectra of ten solutions of varying concentrations were measured by using Vernier SpectroVis Plus Spectrophotometer, the wavelength at which absorbance was at its maximum was recorded for both Red 40 and Yellow 5 solution. Applying absorbance of food dye and beverage at wavelengths chosen to Beer-Lambert law determined the concentrations of Red 5 and Yellow 40 solutions in food dye and beverage. However, in the calculation of concentrations of both dyes, uncertainty were generated and analyzed. Introduction Spectrophotometry is widely used to determine the concentrations of solutes in solutions. In this lab, colored solutions in cuvets are placed in spectrometer, consisted of a spectrograph and a photograph. A spectrograph shoots a light of a certain wavelength, and is calibrated to indicate the color of the light it produces in terms of wavelength, usually expressed in nanometers. The photometer then measures the intensity of the light beam at a given wavelength. The fraction of incident electromagnetic radiation absorbed by several diluted and colored solutions Yellow 5 and Red 40 (25mg/L, 12.5mg/L, 6.25mg/L, 3.125mg/L, 1.5625mg/L). For they were colored solutions, they all have peak wavelengths. After the specific wavelengths of interest were chosen (500.80nm and 423.1nm), the absorbance of unknown solutions were measured when wavelength equal 500.80nm and 423.1nm. Then using the equation that
=423.1nm =500.8nm The concentration of red dye and yellow dye were obtained after solving these equations. Therefore, separate absorbance of different two solutions lead us to find out the concentration of unknown solutions (the mixture of Red 5 and Yellow 40 with certain ratio. Method Yellow 5 and Red 40 of known concentration (50mg/L) were diluted into several different concentrations—25mg/L, 12.5mg/L, 12.25mg/L, 6.125mg/L, 3.1625mg/L. Then, the absorbance spectra for these several yellow 5 and red 40 solutions of different concentrations were measured by using the Vernier SpectroVis Plus Spectrophotometer. Furthermore, two of wavelengths, which are 500.8 nm and 423.1 nm, at which the absorbance was maximized, were chosen as well. The absorbance spectra of Yellow 5 and Red 40 at chosen wavelengths (500.80

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