User:Moira M. Esson/Notebook/CHEM-581/2012/11/19

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Objectives

  1. Test the color change of porphyrin films
  2. Run UV-vis on color changed films

Observations

  • Accidentally used 100mM for Fe2(SO4)3 and Na2SO4. Need to retest that film and prepared 10mM salt solutions.

Color Change and UV-vis of color change

The general protocol for testing color change of films described 2012/11/16 was followed.
Note: The two films stored in 2wt% sulfuric acid were more brittle than previous films. In the future, films will not be stored in sulfuric acid for an extended period of time.
Time change information:

  • Al2(SO4)3 salt solution
Name of Film Time required for color change(min.) Thickness of film(mm)
2.4394g PVOH(22K)+0.5mL GA+0.99 porphyrin 11.80383333 1.1
1.02114g PVOH(22K)+0.5mL GA+1mL porphyrine 100.05 1.5


  • Na2SO4 salt solution
Name of film Time required for color change(min) Thickness of film(mm)
2.4394g PVOH(22K)+0.5mL GA+0.99 porphyrin 8.452 0.6
1.02114g PVOH(22K)+0.5mL GA+1mL porphyrine 74.06667 1


  • Fe2(SO4)3 salt solution
Name of film Time required for color change(min) Thickness of film(mm)
2.4394g PVOH(22K)+0.5mL GA+0.99 porphyrin 2.199 0.3
1.02114g PVOH(22K)+0.5mL GA+1mL porphyrine 15.5335 1.1


Notes:

  • The amount of time needed to facilitate a color change from green back to pink relates to film thickness. The thicker the film, the more amount of time needed to facilitate a color change.
  • Regardless of film type, Fe2(SO4)3 facilitated the fastest color change, indicating an ease of that salt to enter the film.
  • Regardless of film type, Al2(SO4)3 took the longest amount of time to facilitate a color change. This indicated that it was more difficult for the aluminum salt to facilitate a color change.
  • The following two observations(regarding the salts) was not predicted. Based on size, it was thought that sodium sulfate would take the least amount of time. More tests should be run to verify the following results.
  • For the film 1.02114g PVOH(22K)+0.5mL GA+1mL porphyrine, the time was recorded when the edges of the film placed in Al2(SO4)3 and Na2SO4 were still very slightly tinted green.
  • The film 2.4394g PVOH(22K)+0.5mL GA+0.99 mL porphyrin was rerun because it was noted that the film was rinsed with deionized H2O before being placed in the salt solutions.


  • 2.4394g PVOH(22K)+0.5mL GA+0.99mL porphyrin rerun
Salt solution Time required(min) Film thickness(mm)
Al2(SO4)3 5.9978 0.7
Na2SO4 5.4295 0.5
Fe2(SO4)3 2.351 0.3




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