User:Alex Lutz/Notebook/Experimental Chemistry - 481/2018/08/31

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Objective

Measure the UV-Vis spectra of different malachite green solutions in order to create a standard absorption curve.

Description

  1. Measure UV-Vis spectrum of different malachite solutions.
  2. Create 2 new solutions using available stock solutions.
  3. Plot the data and determine extinction coefficients.

Procedure for UV-Vis

  • Since UV-Vis is a non-damaging technique, the sample can be returned after testing.
  1. First clean the cuvette.
    1. Rinse cuvette with water
    2. Rinse cuvette with sodium dodecyl sulfate (SDS) solution
    3. Rinse cuvette with water
    4. Rinse cuvette with 10% HCl solution
    5. Rinse cuvette with water
  2. Add the sample to the cuvette to fill about 3/4 full.
  3. Insert cuvette into UV-Vis.
  4. After UV-Vis runs, save twice (once as a .spec file and another time as a .txt data table).
  5. Remove cuvette from UV-Vis and return sample to container.

Data

  1. Stock solutions of Malachite green made by Dr. Hartings:
    1. 63.1 ppm
    2. 26.8 ppm
    3. 4.78 ppm (3.79083 g of 63.1 ppm Malachite green stock, water added to a total mass of 50.0521 g)
    4. 2.59 ppm (4.75639 g of 26.8 ppm Malachite green stock, water added to a total mass of 49.2598 g)
    5. 1.03 ppm (1.86080 g of 26.8 ppm Malachite green stock, water added to a total mass of 48.6527 g)
    6. 0.637 ppm (1.1903 g of 26.8 ppm Malachite green stock, water added to a total mass of 50.0786 g)
  1. Newly created stock solution of Malachite green
    1. .347 ppm (.275g of 63.1 ppm Malachite green stock, water added to a total mass of 50.078g)
    2. 9.97 ppm (7.91g of 61.3 ppm Malachite green stock, water added to a total mass of 50.08g)

MG1solutionsvswavelength.png 481MGAbsorbanceVsConcentrationSet1.png

Notes

As can be seen with the best fit line, the data did not have as strong of a linear correlation that we would expect from the data suggesting that there were a substantial amount of errors while recording the data. Remeasuring will be required in order to get a better line of best fit.