allura red report

docx

School

Cleveland State University *

*We aren’t endorsed by this school

Course

331

Subject

Chemistry

Date

Dec 6, 2023

Type

docx

Pages

Uploaded by DoctorWombatPerson951

Experiment Title: Determination of a dye concentration using a UV-Vis spectrophotometer Goals: Utilizes UV-vis spectroscopy to determine the concentration of an unknown solution of Allura red dye. Results : A. Serial Dilution  What was the concentration of your stock solution provided? 7*10^-5  Fill out the following the following table of content: 0 [Allura Red], (M Stock Solution Volume Prepared (mL) [Allura Red] (stock) , (M) Volume of Stock Pipetted (mL) Absorbance at  = 504 nm 3.5*10^-6 10 5x10^-5 0.5 0.1327 1.4*10^-5 10 5x10^-5 2 0.4039 2.1*10^-5 10 5x10^-5 3 0.5907 2.8*10^-5 10 5x10^-5 4 0.7816 3.5*10^-5 10 5x10^-5 5 0.9093 B. Calculations: Show the calculations of the volume of the stock solution necessary to prepare each of the stock solutions. (1.5/30 points) 1) 3.5x10 -6 M (3.50*10^-6 M)(10mL)=(5*10^-5 M)( _mL) ( _mL) =(3.50*10^-6 M)(10mL)/(5*10^-5 M) =0.7mL 2) 1.4x10 -5 M (1.40*10^-5 M)(10mL)= (5*10^-5 M)( _mL) ( _mL) =(1.40*10^-5 M)(10mL)/(5*10^-5 M) =2.8 mL 3) 2.1x10 -5 M (2.10*10^-5 M)(10mL)=(5*10^-5 M)( _mL) ( _mL) =(2.10*10^-5 M)(10mL)/(5*10^-5 M) = 4.2 mL 4) 2.8x10 -5 M (2.80*10^-5 M)(10mL)=(5*10^-5 M)( _mL) ( _mL) =(2.80*10^-5 M)(10mL)/(5*10^-5 M) = 5.6 mL

5) 3.5x10 -5 M (3.50*10^-5 M)(10mL)=(5*10^-5 M)( _mL) ( _mL) =(3.50*10^-5 M)(10mL)/(5*10^-5 M) = 7.0 mL Calibration Curve: Create a graph of Absorbance at  (504 nm) versus [Allura Red]. Make sure to have your linear regression passing through the origin point (0,0) 0 0 0 0 0 0 0 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 f(x) = 26093.59 x + 0.03 Absorbance vs Allura Red Allura Red (M) Absorbance (nm) Linear Regression Equation: y=26094x+0.0283 What is the Molar Extinction Coefficient for Allura Red? 26094 M -1 cm -1 Use the linear Regression to calculate the concentration of your unknow solution of Allura Red Unknow Absorbance: 0.1787 Unknown [Allura Red] = 4.6*10^--3 C. Conjugation of Colored compounds Please attach a copy the UV-vis spectra for your colored solution here. Yellow: 575 nm

Green: 550 nm Blue: 460 nm Purple: 410 nm Red: 620 nm Discussion: UV-vis spectroscopy is a technique that is used to determine the absorbance of a solution by measuring the absorbed visible and UV light for organic molecules. Pi and non-bonding electrons are transferred between highest occupied molecular orbitals and lowest occupied molecular orbitals. The Beer-Lambert law uses absorbance, molar absorbance coefficient, molar concentration, and optical path length to show a linear relationship between the amount of light absorbed by a chemical component. A curve of absorbance vs allura red was created to study the differences in absorbed light by different solutions containing concentrations of allura red. The allura red extinction coefficient obtained by the experiment, 26094 M-1 cm-1, was moderately close to the known value. Lambda max is defined as the location of the wavelength where the strongest photon absorption occurs. Electron conjugation and lambda max are directly proportional so as the electrons increase so does the lambda max. On the electromagnetic spectra the color green is complimentary to red, thus green is absorbed revealing an observed color of red, Conclusion: From this lab I learned how UV-vis spectroscopy can be used to identify light absorbed by multiple variations of allura red concentrations. I also learned that by using the calibration curve you can determine the concentration of an unknown sample. This lab also stressed the importance of accurate dilution techniques. References: Thomas, L. Experimental Handout, 5th version. Valencia College Orlando. ChemWatch https://jr.chemwatch.net/chemwatch.web/home (accessed Nov 5, 2023)

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version