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Homework Help: PH to ppm with ammonia chart/problem

  1. Sep 5, 2011 #1
    I need some help calculating basic chemistry. I need to know how much ammonia I need to add to a volume of water to reach the appropriate pH level.

    I have 50 cubic meters of demin water that I need to raise to a pH of 11. Volume is not flowing.
    I am using aqueous ammonia of 25% solution. I was able to find online that a pH of 11 is equal to 50 mg/L (not 100% sure).

    This a two part question:
    How do I calculate the concentration of the solution based on the pH?
    How do I calculate the required volume to dose the 50 cubic meters to reach the pH of 11?

    Also, does anyone have a pH vs mg/L (ppm) in a quick reference chart?

    After some research I found some answers and it calculated (roughly) that I need 15 liters.

    Thanks,
     
  2. jcsd
  3. Sep 5, 2011 #2

    Borek

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    Staff: Mentor

    Even if I believe you, giving a correct answer would be against forum rules.

    Start here:

    http://www.chembuddy.com/?left=pH-calculation&right=pH-weak-acid-base

    While this is about calculating pH for known concentration, information there should help you calculate concentration for a given pH. pKb for ammonia is 4.75

    Your ppms are terribly off, surprisingly, your volume is at least in the correct ballpark.

    I shouldn't write it - but you can find answer pretty fast using my calculators, BATE & CASC.
     
  4. Sep 6, 2011 #3

    Borek

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    Staff: Mentor

    One additional note: if it is about demineralized water used in the industrial settings, final pH will be different than just calculated from the ammonia concentration, as solution will absorb atmospheric carbon dioxide - that will lower the pH.
     
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