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Altering pH of a luminol solution

  1. Oct 12, 2017 #1
    The recipe for luminol solution that I found on the internet is:
    0.2g luminol, 4.0g Na2CO3, 24.0g NaHCO3, 0.5g (NH4)2CO3, 0.4g CuSO4 dissolved in 1 dm3 of water.
    How can I alter the pH of the solution to get a range of pH values from 7 to 14 without affecting the chemisty of the solution?
     
  2. jcsd
  3. Oct 12, 2017 #2

    Borek

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    Staff: Mentor

    Very general answer: you can't. At some point copper hydroxide will precipitate, and the "chemistry" of the solution will change.

    Less general answer: identify buffer in the solution, think how you can change its pH.
     
  4. Oct 12, 2017 #3
    What if I use NaOH and luminol dissolved in 1 dm3 water?
     
  5. Oct 13, 2017 #4

    Borek

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    Staff: Mentor

    Why the volume? What if you used them dissolved in 2 dm3 water?

    Yes, adding NaOH will definitely change pH. But as I said earlier, you can as well change ratio of conjugates making a buffer and prepare solution of a different pH. You won't get far from the original pH this way though.
     
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