Phosphoric Acid

Discussion in 'General Home Brew Equipment Discussion' started by braziliain, Nov 10, 2018 at 12:58 PM.

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  1. Nov 10, 2018 at 12:58 PM #1

    braziliain

    braziliain

    braziliain

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    I recently bought some 75% phosphoric acid for reducing the alkalinity of my tap water after reading of others on here using similar.

    Now I have the bottle and I'm reading the warnings all over it, my question is this:

    Can I use a plastic syringe to measure and dose it? I have both 1ml and 5ml plastic syringes.

    If not, how are you other guys measuring and dosing?

    Google can't seem to answer this one for me...
     
  2. Nov 10, 2018 at 2:03 PM #2

    chthon

    chthon

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    Yes, you can. I also do it like this. It is not that they will dissolve while having them in your hands.

    However, will you use a spreadsheet like Bru'n'water to obtain the correct amount of acid to reduce your alkalinity? A recent experiment I did showed that you really do not need very much acid, and that you are probably better off to first make a bottle of solution which is less concentrated. This makes it simpler to measure the correct amounts.
     
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  3. Nov 10, 2018 at 3:41 PM #3

    braziliain

    braziliain

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    I've actually put my own spreadsheet together because Bru'n'Water didn't handle dilution of liquor in the manner that I wanted.

    I have experiments planned with 2-5L of water to check that my spreadsheet is working and to dial it in if necessary.

    Good to hear I'm ok to use the plastic syringes, that will make life nice and easy. I've thought about diluting the 75% conc down to say 50% or 25% but I'm not sure I've got a suitable bottle to store it in or the chemistry knowledge to get it right!
     
  4. Nov 10, 2018 at 4:41 PM #4

    braziliain

    braziliain

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    Experimented this afternoon.

    4L of water
    Alkalinity at the start 153ppm CACO3

    Target alkalinity 22ppm CACO3. Spreadsheet says 0.6ml 75% conc. Phosphoric Acid

    Alkalinity after adding the acid measured at 19.7ppm CAC03

    That'll do for me! athumb..
     
  5. Nov 10, 2018 at 8:18 PM #5

    chthon

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    Glass bottles are good to go. I use apothecary bottles of 250 mL and 100 mL to store my diluted solutions. It's phosphoric acid, not fluoridic acid which can be used to etch glass.
     
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  6. Nov 10, 2018 at 10:34 PM #6

    braziliain

    braziliain

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    Do you just dilute it say 10:1 then add 10 times as much? Or is the chemistry more complex than that?
     
  7. Nov 10, 2018 at 11:30 PM #7

    Simonh82

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    Are you using the free version of Bru N Water? If so, it's worth bunging Martin $10 for the paid for version (which you get free updates for too). It has quite a bit more functionality and I wouldn't be surprised if the dilution method that you want isn't covered by it. I can't imagine the number of hours of work that has gone into that spreadsheet, so I wouldn't want to try to replicate it myself.
     
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  8. Nov 11, 2018 at 10:22 AM #8

    chthon

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    The basic formula for dilution is Conc1 X Vol1 = Conc2 X Vol2
    The volumes are what you obtain, not what you need to add.

    Say that you start from 75% and want to obtain 250 mL of 25%. Then the equation becomes:

    75% X vol1 = 25% X 250

    Solving this gives: vol1 = 25% X 250 / 75% = 83 mL of the 75% solution.

    Add this in the bottle, then add (250 - 83) mL distilled/RO/demineralised water, 167 mL. Then you have 250 mL of a 25% phosphoric acid solution.
     
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