Suggested Experiments


I. Determination of unknowns.

  1. Start the program and enter your assigned code #.
  2. Turn on the instrument by clicking on the knob at the left front.  
      Manipulate this knob to set the Transmittance to 0.0.

  3. Prepare a standard solution of RED dye by clicking on the arrow
      beside the red rectangle at the top of the page, then click the mouse
      on the squirt bottle to put a solution of red dye in Cell #1.  Record
      the concentration of this red dye solution (ppm).

  4. Prepare a solution of BLUE dye in Cell #2.  Record the concentration
      of this blue dyesolution.

  5. Click on Cell #1 to place the red dye standard in the cell compartment.
  6. Click on SCAN. The observed data will pop up in a gray window.
      Close that window.

  7. Click on the cell compartment or on one of the cells to return
      Cell #1 to the rack.

  8. Click on Cell #2 to place the blue dye standard in the cell compartment.
  9. Click on SCAN. The observed data for Cell #1 and Cell #2 will appear.
10. Inspect the data to select a wavelength (WL1) at which the absorbance
      of the red dye is strong and that of the blue dye is negligible, then a
      wavelength (WL2) at which the absorbance of the blue dye is strong
      and that of the red dye is negligible.

11. Set the wavelength to the value you have chosen for WL1. 
      Click on Cell #0 (distilled water) to place it in the cell compartment. 
      Operate the knob on the rightfront to set the absorbance of this
      solution to 0.000.

12. Place each of the cells in the cell compartment and record their
      absorbance values at WL1.

13. Re-set the wavelength to the value you have chosen for WL2. 
     Place Cell #0 in the cell compartment. Set the absorbance of this
     solution to 0.000.

14. Place each of the cells in the cell compartment and record their
      absorbance values at WL2.

15. Calculate the concentrations of red and blue dye in the unknown
      solutions.

16. Click on "check results"and see how you've done. 
      If there are errors, re-check your calculations.

II. Comparing Spectra.

1. Click on "dump solutions".
2. Prepare a new red dye solution of equal volumes of red dye and water.
3. Prepare a new blue dye solution of equal volumes of blue dye and water.
4. Prepare a mixed solution of equal volumes of red dye and blue dye.
5. Place each of these solutions in the cell compartment and click on SCAN.
6. With the results of all three scans showing in the gray window,
    select COPY from the EDIT menu.

7. Open a Spreadsheet Program or a Word Processor Program
    and PASTE the data.

8. Use the Spreadsheet Program to create and print a graph of your data.
    If this is not available,use graph paper to create the graph.




 
 


 
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