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equation.... throw me a bone please

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  • equation.... throw me a bone please

    so here it is

    CaCO7=30ppm or less

    how much sulfuric acid do i need to add to 1470 gals H-2-0 to do this

  • #2
    Chemical Engineer here to help you...

    So you want to add sulfuric acid (H2SO4) to water and get CaCO7?? CO7 isn't even an ion. Are you looking for CaCO3 maybe? And where to you plan on getting the Ca ions? Unless your already assuming your water is hard enough to already have Ca present. Basically either you had a typo, left out some information, or are going down the wrong path. I'm here to help though so get back to me...


    • #3
      Yo Straub. You are correct...I was in a bit of a hurry and should have doubled checked before I posted. We have about 240 ppm CaCO3 (calcium carbonate) and want less than 30 ppm calcium carbonate. So, how much sulfuric acid to add to 1475 gallons of brewing liquor to get this done?

      I am not to familiar with any of this, I am posting at the request of our brewmaster...



      • #4
        Still Need Some Information Mason

        Ok, now I understand what you are trying to do. You have too much CaCO3 already and are trying to eliminate it by adding acid (in your case H2SO4).
        So you want this to occur... CO3^2- + 2H+(acid source) --> CO2 + H2O
        I'm going to have to know the concentration of your sulfuric acid before I can give you a volume. Also I should let you know that the Ca (calcium ions) will remain in the water and you can't get rid of it. The final product will be CaSO4 with some Ca(HSO4)2. Is this acceptable?


        • #5
          OK. A little water chemistry. H2SO4, Sulfuric Acid, will neutralize CaCO3 with a high degree of efficacy (97%).

          So if you have 240 ppm and want to get down to 30 ppm with 1475 gallons you will need:

          (240mg/l-30mg/l)(3.79liters/gallon)(1475gallon)(1 mol CaCO3/100,000 mg)=11.7 moles CaCO3

          Amount of Sulfuric Acid required= (11.7 molar equivalents) (.97)=11.4

          So, if you have 5 molar H2SO4, you would have to add:

          (1 liter/5moles)(11.4 moles)(1 gallon/3.79 liters)= 0.6 gallons H2SO4

          My math may be wrong here, so I reccomend you have someone with some chemistry knowledge double check.

          What concentration acid are you using anyway?
          Steve G


          • #6
            Math is right on...

            I did the calculations looking up pKa's and some other stuff and found an efficacy of about .986 which is close enough for your needs. Use the equation below to find the volume you need to add. I caution you though to add it slowly. If you add highly concentrated sulfuric acid to water it will heat up due to entropy effects. I suggest using a lower concentration and adding slowly!

            (.6 gal H2SO4)*(5 M/ whatever molar you are using) = volume you need....

            For example...
            1 M = 3 gallons
            3 M = 1 gallon
            8 M = .375 gallon
            10 M = .3 gallon
            12 M = .25 gallon


            Also don't forget adding sulfuric acids adds sulfate ions. Take into account what that does. Maybe you want to consider hydrochloric acid which only leaves extra chloride ions in the water. Just something to think about... Let us know how it turns out.


            • #7
              Thinking out of my cardboard box...

              If this is a constant problem for all products consider RO filtration and add back salts.
              Brewmaster, Minocqua Brewing Company
              "Your results may vary"


              • #8
                I did find one error in my math now that I look at it a second time:

                Amount of Sulfuric Acid required= (11.7 molar equivalents) (.97)=11.4

                Should have been:

                Amount of Sulfuric Acid required= (11.7 molar equivalents)/(.97)=12.1

                Doesn't really change the final value.

                Straub, thanks for double checking my math!

                A couple of things to consider when acidifying your water:

                SO4 levels above 100 ppm can cause a little bit of risk with label claims, since once you get above this level, it is considered an additive! This is not a concern if you are just making keg beer for brewpub consumption, but in my situation it would be unacceptable.

                Hydrochloric acid is a little dangerous to use because of the fuming properites. Use extreme caution in use and storage of this stuff! Also, excessive Chloride ion can cause yeast floc. and clarity problems. I don't know all the regulatory issues with HCl, but I think it may be considered a poison, so although it wouldn't hurt anyone if used properly, the Health Department may not approve.

                I consider Phosphoric Acid the safest acid to use in a brewery, but although it is great for cleaning, it is less effective at neutralizing Carbonates.

                Sulfuric Acid is used by the Heineken brewery and many Domestic Mega, Micro, and Regional breweries for water treatment applications.

                When using acid, just make sure to treat your brewing liquor well in advance of brewing to ensure good mixing and neutralization.
                Steve G